Can a new satellite constellation create sunlight on demand?SpaceX/Flickr, CC BY
A proposed constellation of satellites has astronomers very worried. Unlike satellites that reflect sunlight and produce light pollution as an unfortunate byproduct, the ones by US startup Reflect Orbital would produce light pollution by design.
The company promises to produce “sunlight on demand” with mirrors that beam sunlight down to Earth so solar farms can operate after sunset.
It plans to start with an 18-metre test satellite named Earendil-1 which the company has applied to launch in 2026. It would eventually be followed by about 4,000 satellites in orbit by 2030, according to the latest reports.
So how bad would the light pollution be? And perhaps more importantly, can Reflect Orbital’s satellites even work as advertised?
Bouncing sunlight
Sunlight can be bounced off a wristwatch to produce a spot of light . M. Brown, CC BY-SA
In the same way you can bounce sunlight off a watch face to produce a spot of light, Reflect Orbital’s satellites would use mirrors to beam light onto a patch of Earth.
But the scale involved is vastly different. Reflect Orbital’s satellites would orbit about 625km above the ground, and would eventually have mirrors 54 metres across.
When you bounce light off your watch onto a nearby wall, the spot of light can be very bright. But if you bounce it onto a distant wall, the spot becomes larger – and dimmer.
This is because the Sun is not a point of light, but spans half a degree in angle in the sky. This means that at large distances, a beam of sunlight reflected off a flat mirror spreads out with an angle of half a degree.
What does that mean in practice? Let’s take a satellite reflecting sunlight over a distance of roughly 800km – because a 625km-high satellite won’t always be directly overhead, but beaming the sunlight at an angle. The illuminated patch of ground would be at least 7km across.
Even a curved mirror or a lens can’t focus the sunlight into a tighter spot due to the distance and the half-degree angle of the Sun in the sky.
Would this reflected sunlight be bright or dim? Well, for a single 54 metre satellite it will be 15,000 times fainter than the midday Sun, but this is still far brighter than the full Moon.
Last year, Reflect Orbital’s founder Ben Nowack posted a short video which summarised a test with the “last thing to build before moving into space”. It was a reflector carried on a hot air balloon.
In the test, a flat, square mirror roughly 2.5 metres across directs a beam of light down to solar panels and sensors. In one instance the team measures 516 watts of light per square metre while the balloon is at a distance of 242 metres.
For comparison, the midday Sun produces roughly 1,000 watts per square metre. So 516 watts per square metre is about half of that, which is enough to be useful.
However, let’s scale the balloon test to space. As we noted earlier, if the satellites were 800km from the area of interest, the reflector would need to be 6.5km by 6.5km – 42 square kilometres. It’s not practical to build such a giant reflector, so the balloon test has some limitations.
So what is Reflect Orbital planning to do?
Reflect Orbital’s plan is “simple satellites in the right constellation shining on existing solar farms”. And their goal is only 200 watts per square metre – 20% of the midday Sun.
Can smaller satellites deliver? If a single 54 metre satellite is 15,000 times fainter than the midday Sun, you would need 3,000 of them to achieve 20% of the midday Sun. That’s a lot of satellites to illuminate one region.
Another issue: satellites at a 625km altitude move at 7.5 kilometres per second. So a satellite will be within 1,000km of a given location for no more than 3.5 minutes.
This means 3,000 satellites would give you a few minutes of illumination. To provide even an hour, you’d need thousands more.
And yet, that vast constellation would deliver only 20% of the midday Sun to no more than 80 locations at once, based on our calculations above. In practice, even fewer locations would be illuminated due to cloudy weather.
Additionally, given their altitude, the satellites could only deliver illumination to most locations near dusk and dawn, when the mirrors in low Earth orbit would be bathed in sunlight. Aware of this, Reflect Orbital plan for their constellation to encircle Earth above the day-night line in sun-synchronous orbits to keep them continuously in sunlight.
Cheaper rockets have enabled the deployment of satellite constellations. SpaceX/Flickr, CC BY-NC
Bright lights
So, are mirrored satellites a practical means to produce affordable solar power at night? Probably not. Could they produce devastating light pollution? Absolutely.
In the early evening it doesn’t take long to spot satellites and space junk – and they’re not deliberately designed to be bright. With Reflect Orbital’s plan, even if just the test satellite works as planned, it will sometimes appear far brighter than the full Moon.
A constellation of such mirrors would be devastating to astronomy and dangerous to astronomers. To anyone looking through a telescope the surface of each mirror could be almost as bright as the surface of the Sun, risking permanent eye damage.
The light pollution will hinder everyone’s ability to see the cosmos and light pollution is known to impact the daily rhythms of animals as well.
Although Reflect Orbital aims to illuminate specific locations, the satellites’ beams would also sweep across Earth when moving from one location to the next. The night sky could be lit up with flashes of light brighter than the Moon.
The company did not reply to The Conversation about these concerns within deadline. However, it told Bloomberg this week it plans to redirect sunlight in ways that are “brief, predictable and targeted”, avoiding observatories and sharing the locations of the satellites so scientists can plan their work.
The consequences would be dire
It remains to be seen whether Reflect Orbital’s project will get off the ground. The company may launch a test satellite, but it’s a long way from that to getting 250,000 enormous mirrors constantly circling Earth to keep some solar farms ticking over for a few extra hours a day.
Still, it’s a project to watch. The consequences of success for astronomers – and anyone else who likes the night sky dark – would be dire.
The number of satellites visible in the evening has skyrocketed.
Michael J. I. Brown receives research funding from the Australian Research Council.
Matthew Kenworthy receives research funding from the Dutch Research Council (NWO).
Back in the 1980s, when Shimon Sakaguchi was a young researcher in immunology, he found it difficult to get his research funded. Now, his pioneering work which explains how our immune system knows when and what to attack, has won him a Nobel prize.
Sakaguchi, along with American researchers Mary Brunkow and Fred Ramsdell, were jointly awarded the 2025 Nobel prize in physiology or medicine for their work on regulatory T-cells, known as T-regs for short, a special class of immune cells which prevent our immune system from attacking our own body.
In this episode of The Conversation Weekly podcast, Sakaguchi tells us about his journey of discovery and the potential treatments it could unlock.
Sakaguchi was inspired by an experiment involving newborn mice conducted by his colleagues at the Aichi Cancer Center Research Institute in Nagoya. They’d removed the thymus from mice three days after they were born. It was already known that the thymus is important in the development of immune self-tolerance: it’s where T-cells, a type of lymphocyte or white blood cell, that could attack the body are isolated and destroyed. Sakaguchi was intrigued by what happened. He said that if you remove the thymus in a normal mouse in the neonatal period, you would expect immune deficiency because the lymphocytes are gone.
But what happened is just the opposite: they developed autoimmune diseases. This disease is very similar to what we see in humans … but of course, human patients are not removed of the thymus, so there must a common mechanism, which can explain spontaneous autoimmune diseases in humans.
Sakaguchi decided to try a new experiment to stop the mice’s immune system going into overdrive. When he took some T-cells from genetically identical mice and injected them back into the mice who’d had their thymus removed, he found that autoimmune disease can be prevented. “ This suggests that there must be a T-cell population which can prevent disease development,” he said.
In the 1980s, Sakaguchi said it was not easy to get research funding “because the immunology community were very sceptical about the existence of such cells”. He spent time in the US and he says he was “very fortunate” to be supported by a grant from a private foundation.
After ten years of looking, he published a paper in 1995 setting out his discovery of regulatory T-cells, which act as the body’s security guard, controlling any adverse reactions and keeping the immune system in balance in a process called peripheral tolerance. When these T-regs don’t work properly, this can cause autoimmune diseases. Later work by Sakaguchi, and his fellow laureates Brankow and Ramsdell, discovered the specific gene, called Foxp3 that controlled T-regs.
Cancer, auto-immune treatments and more
When Sakaguchi started out, his interest was in autoimmune diseases and how they occur. “But in the course of my research we have gradually understood that T-regs are more important,” he says. These cells are now implicated in the way cancer attacks the body, as well as the acceptance of organ donations. Sakaguchi is also working on new ways to harness T-regs for treatment, and also on converting other, attacking types of T-cells, into T-regs to target specific autoimmune diseases.
His immediate hope is that some of the clinical trials for cancer immunotherapy can become a reality for treating patients. But he’s also fascinated by recent research which shows the importance of T-regs in diseases which cause inflammation – and what this could mean for potential to repair damaged tissue.
Neuro-degenerative diseases such as Alzheimer’s disease or Parkinson’s disease, all involve inflammation. By just targeting that kind of inflammation, we maybe [could] stop the disease progressions, or delay the disease progression. We hope that it is very true and then it really works for such diseases.
This episode of The Conversation Weekly was produced by Mend Mariwany and Katie Flood and is hosted by Gemma Ware. Mixing and sound design by Michelle Macklem and theme music by Neeta Sarl.
Listen to The Conversation Weekly via any of the apps listed above, download it directly via our RSS feed or find out how else to listen here. A transcript of this episode is available on Apple Podcasts or Spotify.
Shimon Sakaguchi is the scientific founder and a director of RegCell, a Japanese start-up working on treatments based on regulatory T-cells. He is also a scientific advisor for biotechnology company Coya Therapeutics.
As negotiators meet in Egypt to discuss a Trump-backed peace proposal, displaced Gazans make a daily trek to find drinking water.AP Photo/Abdel Kareem Hana
Tony Blair, the man being tapped by U.S. President Donald Trump to help oversee governance of a postwar Gaza, has ample experience with peace processes.
As British prime minister, Blair helped usher through the 1998 Good Friday Agreement that did much to end decades of sectarian violence in Northern Ireland. After leaving office, he was also special envoy to the so-called Quartet – a diplomatic effort to find a lasting solution to the Israeli-Palestinian conflict.
As Hamas’ Oct. 7, 2023, attack on Israel and the subsequent devastation in Gaza, described recently as genocide by a U.N. body, make clear, that attempt failed.
The 20-point peace plan that negotiators are currently discussing in Egypt is light on details. But it outlines the return of the remaining Israeli hostages held by Hamas, the demilitarization of the Gaza Strip and the creation of an international security force to operate on the ground. Notably, the plan does not support the removal of Palestinians from Gaza – something that was present in previous proposals by the Trump administration and which human rights advocates noted amounts to ethnic cleansing.
On Oct. 8, 2025, Trump announced that an initial phase involving the exchange of hostages for prisoners and a pause in fighting had been agreed upon. But negotiations continue on sticking points, including the disarming of the militant group.
Among other things, the deal also provisions a postwar Gaza governed by an interim “technocratic” and “apolitical” Palestinian committee. This temporary body will be overseen by a “Board of Peace” run by Trump himself. Other unspecified members will be added, but the only one mentioned in the proposals is Blair, who according to reports had been in talks with the Trump administration for some time crafting the current peace plan.
As a scholar of international relations and Palestinian politics, I fear the proposal contains the same limitations and failings that plagued previous peace plans pushed on Palestinians from outside bodies – including both Blair’s Quartet efforts and the earlier Oslo Accords – and too little of what made Northern Ireland peace stick.
Nor does the plan include any meaningful Palestinian input, either through legitimate representatives of the Palestinian people or through mechanisms to ensure the Palestinian public’s buy-in.
Instead, the new framework is asymmetric, providing the Israeli government many of its political objectives while imposing multiple layers of international control on and vague assurances to the Palestinian people – and only if they comply.
As such, the plan continues the trend of what political scientists describe as “illiberal peace” in conflict resolution.
In a 2018 paper, scholars described an “illiberal peace” as one in which “cessation of armed conflict is achieved in ways that are … unashamedly authoritarian.” Such a peace is achieved through “methods that eschew genuine negotiations among parties to the conflict, reject international mediation and constraints on the use of force, disregard calls to address underlying structural causes of conflict, and instead rely on instruments of state coercion and hierarchical structures of power.”
From left, Irish Prime Minister Bertie Ahern, U.S. Sen. George Mitchell and British Prime Minister Tony Blair pose together after signing the Good Friday Agreement on April 10, 1998. Dan Chung/Pool Photo via AP, File
The Northern Ireland case study
That stands in contrast to peace agreements that have succeeded elsewhere using more inclusive diplomatic frameworks, like in Northern Ireland.
For 30-plus years, the territory was engulfed in sectarian violence between the mainly Protestant “loyalists” who wanted to remain part of the U.K. and the Catholic minority that wished to be part of a united, independent Irish republic.
The Northern Ireland peace process also explicitly engaged with the Irish public and offered the people input through two separate referendum votes. People in Northern Ireland voted on whether to support the plan, and people in the Republic of Ireland voted on whether to authorize the Irish state to sign the agreement.
This inclusive and democratic process has been able to sustain a cessation of conflict for the past 27 years.
While Blair didn’t start the Northern Ireland peace process, his government played a pivotal role, and it was he who memorably noted “the hand of history” on the shoulder of those involved in the final days of negotiation.
A failed Oslo counterexample
The Northern Ireland process stands in direct contrast to many of the failed peace processes attempted in the Middle East, which fall more in line with the “illiberal peace” concept.
The most serious push for lasting peace was the Oslo Accords in 1993, in which the Palestine Liberation Organization accepted Israel’s right to exist, forgoing its claims to much of historic Palestine, in return for Israel’s acknowledgment of the PLO as the legitimate representative of the Palestinian people.
That process led to the creation of the Palestinian Authority, which was meant to exercise limited governance on an interim basis, and presidential and parliamentary elections in order to facilitate the input of the Palestinian public. But as many former U.S. officials have since admitted, the accords were asymmetric: They offered Palestinians recognition under the PLO but little pathway to achieve a negotiated solution under conditions of occupation by a far more powerful sovereign country.
U.S. President Bill Clinton applauds as Israeli Prime Minister Yitzhak Rabin, left, and Palestine Liberation Organization Chairman Yasser Arafat look on after the signing of the Oslo Accords in 1993. AP Photo/Dennis Cook
That peace process fell apart when that asymmetry became clear. The two parties meant very different things when they used the word “state.” The Israel government envisioned some form of limited self-governance for the Palestinians and continued its settlement expansion and military occupation. The Palestinians, on the other hand, envisioned a legitimate state exercising sovereignty.
Adding to the problems, Palestinians never had equal negotiating power, and the accords lacked a neutral arbiter in the U.S., the leading mediator.
Oslo was intended to be a time-limited process to give negotiators space to resolve outstanding conflict issues. In practice, it served to give long-term diplomatic cover for a status quo in which Israeli governments moved away from a two-state solution while Palestinians became more politically and geographically fragmented under worsening hardship and violence.
The Oslo peace process fell apart in the early years of Blair’s government, at the same time as he was helping put the finishing touches on the Good Friday Agreement.
The necessity of public buy-in and an inclusive process was evident to many onlookers to the divergent fortunes of both peace processes.
Repeating failed lessons in Gaza?
In the Israeli-Palestinian context today, Blair risks repeating the mistakes of Oslo. He is poised to sit on an undemocratic international body overseeing a people under a de facto military occupation.
As a representative for the Quartet, Tony Blair waves to the media in front of Palestinian officials in Ramallah in the West Bank in 2012. AP Photo/Majdi Mohammed
Further, while the Trump plan is reliant on Hamas’ approval, there is no role for the group after the initial stage. In fact, the framework explicitly states that Hamas must be excised from any future discussions of postwar Gaza. Moreover, no other Palestinian group has any direct involvement; Hamas’ main rival Fatah – the party that is in control of the Palestinian Authority in the occupied West Bank – is only briefly mentioned. As for that Palestinian Authority, there is only a vague line about reforming the body.
Similarly, there has been no mention of what the Palestinian people might actually want. In this way, the body being proposed recalls the creation of the U.S.-led Coalition Provisional Authority during the invasion of Iraq. That body governed Iraq immediately following the invasion and was criticized for corruption and lack of transparency.
The failure of the Iraq War, and the U.K.’s involvement in it, contributed to Blair’s resignation as prime minister in 2007, after which he took on the role of special envoy to the Quartet. Led by the U.N., U.S., EU and Russia, the Quartet was tasked with preserving some form of the two-state solution and implementing economic development plans in Palestinian cities.
But it, too, failed to address the changing political realities on the ground as Israeli settlements expanded and the military occupation deepened.
The underlying assumption about the Quartet, critics contend, is that it largely ignored the Palestinian right to self-determination and sovereignty; rather, it focused on marginally improving economic conditions and Band-Aid initiatives.
The latest U.S.-backed proposal cribs heavily from the approach. Even if it does bring about a welcome respite from the suffering in Gaza in the short term, I believe a durable, mutually agreed upon resolution to the decades-long Israeli-Palestinian conflict requires what Trump’s plan sidelines: Palestinian self-determination.
In Northern Ireland, Blair once understood the importance of neutral mediation and the buy-in of all parties to the conflict and the people themselves. The plan he is involved with now appears to be operating with a far different calculus.
Dana El Kurd is affiliated with the Arab Center Washington.
After two years of violence and the deaths of 68,000 Palestinians and more than 1,200 Israelis, most of them civilians, it has been reported that Hamas and the Netanyahu government will sign a phase 1 ceasefire agreement. This is the first part of a 20-point plan promoted by the US president, Donald Trump, and supported by the major Arab power brokers in the region.
What we know so far is that Israel will cease it’s military assault in Gaza. Hamas, meanwhile, has agreed to free the remaining 20 Israeli hostages still alive in Gaza.
The Conversation’s international affairs editor Jonathan Este spoke with Scott Lucas, a Middle East expert at University College Dublin, who addressed several key issues.
How is this different to previous ceasefire agreements?
Until we have details, this agreement is similar to the phase 1 60-day ceasefire at the start of 2025. There is a pause in the killing, particularly from the Israeli side, but lasting arrangements remain to be confirmed.
The key difference is that Hamas released only some hostages and bodies in the previous ceasefire. This time they are freeing all hostages and the bodies which can be collected, in return for a still unannounced number of Palestinian detainees released from Israeli prisons.
That gives up Hamas’s main leverage against not only Israeli attacks but also the Netanyahu government’s occupation and veto on aid to Gaza.
So key elements of a lasting deal – the extent of the Israeli military’s withdrawal, the restoration of aid, the establishment of governance and security in the Strip – will rest on guarantees and who provides them.
What are the possible sticking points for the rest of the deal?
The immediate “sticking points” are whether central provisions will be agreed in further discussions.
The Israelis will demand complete disarmament by Hamas and possibly the expulsion of some of its officials. Hamas is likely to respond with rejection of any forced removals and its retention of “defensive” weapons.
The make-up of the international “board” overseeing the strip is vague beyond Donald Trump declaring himself the chair and no provision for any Palestinian representation. Hamas will probably seek some Palestinian membership.
At this point, the International Stabilization Force for the Strip is a wish rather than a plan. Israeli agreement to a force replacing its military in Gaza is far from assured, especially as it is not clear who will contribute personnel. The Italian foreign minister, Antonio Tajani, has offered to send troops to contribute to the force.
The plan for a day-to-day government to administer the Strip is equally sketchy. While the presence of Palestinian technocrats is mentioned in Trump’s “plan”, we do not know who these will be. We know that Hamas is excluded. Israel is also likely to veto the Palestinian Authority in the short-term. And the release from imprisonment of potential Palestinian leaders – such as Marwan Barghouti, who has been held by Israel for more than 20 years – is not confirmed.
And before consideration of all of these, there is the question of the far-right in the Netanyahu cabinet. The finance minister, Bezalel Smotrich, and national security minister, Itamar Ben-Gvir, have yet to comment on the latest news, but have previously opposed any deal short of the “total” defeat of Hamas and a long-term Israeli occupation. Neither have threatened to block the agreement – so far – but they have expressed opposition.
How much of this is due to pressure from Arab states?
While many headlines are likely to give the credit to Trump and his envoys, son-in-law Jared Kushner and real estate developer Steve Witkoff, the role of Arab states has been vital.
A month after Israel shattered Qatar’s sovereignty with the airstrike trying to assassinate Hamas’s negotiators, the Gulf state and Egypt were the brokers of this Phase 1 agreement. Behind the scenes, other Arab states and Turkey were urging Hamas to accept the Trump “plan” in principle and to reach a deal to release the hostages.
Those states will be needed for the next phase, particularly if Trump threatens to return to his previous position of a blank cheque for Israeli military operations and cut-off of aid.
Is there a future for Palestinian civilians in Gaza?
I hope so. The immediate issue is survival. The Israeli attacks have been paused. The urgent issue is getting essential aid into the Strip. Then it is a matter of being able to return to what is left of homes. The Trump administration has dropped its talk of displacement, stemming the demand of Netanyahu’s far-right ministers for the removal of many Gazans.
However, after two years of scorched-earth tactics by Israel, little is left of many of those homes. The majority of the health sector has been destroyed, as have many schools and other public buildings. Rafah has been razed, and Gaza City’s high rises have been blown apart.
Recovery cannot just focus on the profits to be made – including for Trump, Kushner, and Gulf state business interests – from the “development” of Trump’s “Riviera of the Middle East”. It has to begin with day-to-day subsistence for the civilians who have paid the heaviest price in this mass killing.
Does Trump get his Nobel peace prize now?
I don’t care. Sometimes good things happen from a convergence of cynical and self-serving motives. Trump is desperate for the Nobel peace prize because Barack Obama received it in 2009. Kushner, whose investment fund is bankrolled by Saudi Arabia and Qatar, and Gulf state entrepreneurs see the possibility of large profits. US-Gulf relations need to be repaired after the shock of Israel’s airstrike inside Qatar.
If that means lives are saved, fine. But those lives need to be saved not just for today or tomorrow. They need to be respected and supported with a lasting agreement for security and welfare.
And that would mean a two-state solution for both Palestinians and Israelis – something which the Netanyahu government and the Trump administration will not countenance. For Netanyahu and his ministers are devoted to expanding Israel’s illegal settlements, with the accompanying threat of violence, in the West Bank.
Celebrate phase 1 on the behalf of the Israeli hostages, their families, and Gaza’s civilians. And be clear about what is needed for phase 2, phase 3 and beyond.
Scott Lucas does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Source: The Conversation – Global Perspectives – By Reihana Mohideen, Principal Advisor, Just Energy Transition and Health, Nossal Institute for Global Health, The University of Melbourne
For the first time, renewables have toppled coal as the world’s leading source of electricity, in keeping with International Energy Agency projections for this historic shift.
But progress is uneven. The shift away from fossil fuels has slowed in the United States and the European Union – but accelerated sharply in developing nations.
China attracts headlines for the sheer scale of its shift. But many smaller nations are now taking up clean energy, electric vehicles and battery storage at remarkable speed, driven by governments, businesses and individuals.
Importantly, these moves often aren’t about climate change. Reasons range from cutting dependence on expensive fossil fuels and international market volatility to reducing reliance on unreliable power grids to finding ways to boost livelihoods.
Pakistan’s enormous solar boom is partly a response to spiking power prices and grid unreliability. Meanwhile Pacific nations see clean energy as a way to slash the crippling cost of importing diesel and expand electricity access.
My research has given me insight into the paths four countries in South Asia have taken to seize the benefits of clean technology, each shaped by unique pressures and opportunities. All are moving rapidly, blending necessity with ambition. Their stories show the clean energy path isn’t one-size-fits-all.
Bhutan: from hydropower giant to diversified energy
The landlocked Himalayan kingdom of Bhutan has long relied on hydroelectricity. But the country faces a persistent challenge: seasonal variability.
Most of Bhutan’s plants are run-of-the-river, meaning they don’t have large dams. As a result, power generation drops sharply during dry winter months when river flows are low, particularly between January and April.
At the same time, rapid industrialisation has driven up demand for power, outstripping winter capacity. Climate change is expected to worsen this variability.
During these months, Bhutan shifts from its role as clean-energy exporter to an importer, buying electricity from India. But imports aren’t a long-term solution.
To secure reliable supply year-round, Bhutan’s government is diversifying energy sources. To that end, up to 300 megawatts of solar is expected to be installed, potentially as soon as next year. Bhutan’s first utility-scale solar farm is under construction.
Over time, Bhutan will blend hydro with solar, wind and biomass to create a more balanced clean energy mix.
Bhutan has long relied on hydroelectricity. But authorities are moving to find new sources of power as demand surges and river flows become less reliable. Kuni Takahashi/Getty
Nepal: electric cars in Kathmandu
Nepal has long imported all its petrol from India. But when India launched an unofficial blockade in 2015, vital supplies and fuel tankers stopped coming. Fuel prices surged. People queued for days at petrol stations, while black-market prices soared and public transport collapsed. Households, already enduring many hours of daily blackouts, faced even worse conditions.
The crisis exposed Nepal’s deep vulnerability. The mountainous nation makes its own electricity, largely through hydropower. But it had to import petrol.
In 2018, authorities launched an ambitious program to shift to electric vehicles and free the nation from dependence on imports. Electric vehicles would charge on domestic hydropower and reduce Kathmandu’s well-known air pollution. The plan called for electric vehicles to reach 90% share of new commuter vehicle sales (including popular two-wheelers) by 2030.
This year, the electric vehicle share for new four-wheel vehicles reached 76%, jumping rapidly in just the past year. Exemptions and incentives have supported this growth. As electric vehicles surge, new charging station and maintenance businesses have emerged.
It’s not all smooth sailing. A protest movement recently overthrew Nepal’s government, creating uncertainty. Analysts warn stable government policy and infrastructure investment will be essential.
Electric vehicles are soaring in popularity in Nepal. Pictured: the opening of an event by Chinese carmaker BYD in Kathmandu in February 2025. Chinese News Service/Getty
Sri Lanka: innovation emerging from crisis
Between 2022 and 2023, a serious economic crisis hit Sri Lanka. Citizens reeled from severe energy shocks, such as fuel shortages, 12-hour blackouts and punishing electricity price hikes of over 140%. Half a million people were disconnected from the grid as they were unable to pay.
The crisis showed how fragile the island nation’s energy system was. Authorities looked for better options. Hydroelectricity has long been a mainstay, but solar and wind are growing rapidly.
Sri Lanka runs on about 50% renewables, with hydro the largest contributor by far. By 2030, the goal is to reach 70% renewable energy.
While renewables offer cheap power, they have to be coupled with energy storage and new systems to integrate them into the grid.
In response, universities, international partners and companies have worked to integrate renewable energy in the grid, developing artificial intelligence-based systems to improve reliability and supply to consumers. For instance, they can reduce voltage fluctuations associated with high uptake of rooftop solar. Importantly, some of these projects have a gender focus, prioritising women-led small enterprises and training for women engineers.
The crisis may prove a turning point by exposing vulnerabilities and pushing Sri Lanka to adopt new energy solutions.
After a severe energy crisis gripped Sri Lanka, authorities began looking for ways to reduce reliance on imported fossil fuels. Pictured: a closed service station in Colombo in late 2022 with a sign warning of no petrol. Ishara S. Kodikara/Getty
Maldives: bringing solar to diesel-dependent islands
Few countries are more vulnerable to fossil fuel dependence than the Maldives. Spread across 1,000 islands, the nation relies on imported diesel for power generation, with high transport costs and exposure to oil price swings.
In 2014, Maldivian authorities launched the Preparing Outer Islands for Sustainable Energy Development project as part of a plan to reach net-zero by 2030. The project focuses on around 160 poorer islands further from the capital, progressively replacing a reliance on diesel generators with solar arrays, battery storage and upgraded power grids.
Women’s economic empowerment is a priority, as women-led enterprises run solar systems and utilities train female operations officers. The Maldives government released a 2030 roadmap, which has a welcome focus on the “just energy transition” – ensuring communities benefit equitably.
For the Maldives, renewables are more than an environmental choice — they are a lifeline for economic survival and resilience.
Lessons from the margins
While these energy transitions rarely make global headlines, Bhutan, Nepal, Sri Lanka and the Maldives show how smaller economies are finding their own pathways to cleaner, more resilient energy.
Their reasons to act stem from different crises, from blockades to economic upheaval. But each nation is working to turn challenge into opportunity.
Reihana Mohideen has previously consulted for the POISED project in the Maldives.
A proposed one dollar coin featuring US President Donald Trump is causing ructions across the political divide. It’s also provoking discussion in the world of ancient Roman numismatics (coin studies).
The proposed coin depicts Trump in profile on one side (the obverse). On the other side (the reverse) the president raises his fist in defiance accompanied by the words “fight, fight, fight”.
While only a draft proposal, the coin could be minted in 2026 to mark 250 years since the US declaration of independence. But an old lawprohibits the “likeness of any living person” from being “placed upon any of the bonds, securities, notes, fractional or postal currency of the United States.”
More than 2,000 years ago, the depiction of living figures on Roman coins caused similar ructions.
It came at a time when the Roman republic was in trouble. The republic would crumble altogether soon after, ushering in the long period of Rome being led by emperor-kings who saw themselves as almost akin to gods.
Perhaps the American republic is at a similar stage.
Sulla’s image on a coin
Rome was said to be founded by the mythical king Romulus, who killed his own twin (Remus). The fledgling state was led by seven kings before it became a republic in about 509 BCE.
By the late second century BCE it was led by Roman general and politician Gaius Marius. Marius and his later rival, Lucius Cornelius Sulla Felix, broke many of the republic’s long-held conventions. They also fought Rome’s first major civil war.
In 88 BCE, while consul, Sulla marched an army on Rome to defend the city from “tyrants” (by which he meant the faction of Marius, who had ousted him). After Sulla won the civil war that followed, he held the dictatorship from 82-79 BCE. Dictatorships were only to be held for six months in times of emergency. Sulla claimed the emergency was ongoing.
As part of this he ordered a list (known as proscriptions) of enemies drawn up. Hundreds or even thousands were killed and had property confiscated.
In the same year a silver coin (called a denarius) was minted in Sulla’s name. One side featured Sulla himself riding in a four-horse chariot.
This was the first time a living person was depicted on a Roman coin. Up to this point only gods and mythological figures had that honour.
It was highly unusual.
Caesar’s challenge to the old republic
Sulla was the first but he wouldn’t be the last leader of the Roman republic to have his image on a coin.
In 44 BCE Julius Caesar went a step further. Only months before his assassination, coins appeared with Caesar’s bust dominating their obverses. Some included the words dict perpetuo meaning “dictator for life”.
By this time, Caesar and many before him, including Marius and Sulla, had broken the mould of the old republic.
From 46-44 BCE he held the consulship, which was only meant to be held for a one-year term at a time. (Sulla held the dictatorship three years running, which partly set the scene for Caesar’s later emergence and the final breakdown of the republic.)
For many at the time, it seemed Caesar was moving the republic in the direction of monarchy. In January 44 BCE, when a throng hailed him as “rex” (king) Caesar responded, “I am Caesar and no king”. His very name was by now more powerful.
The coins of 44 BCE containing a profile bust of Caesar were an important part of his public program, and part of his challenge to republican convention.
Sulla paved the way 40 years before.
The parallels with Trump are hard to miss
Some emphasise that Caesar did not directly order his image to be placed on coins. Those wanting to curry favour read the room and Caesar did not object.
A similar scenario appears to be playing out with the coin design bearing Trump’s image.
The parallels with Trump are hard to miss. Trump has signed more than 200 executive orders in less than nine months. His predecessor Joe Biden issued 162 in his entire presidency.
Trump’s deployment of federal troops to US cities under emergency decrees provokes cries of tyranny. Sulla’s march on Rome and the proscriptions that followed drew a similar response.
The possibility of a one dollar coin depicting Donald Trump on both sides echoes the coins of Sulla and Caesar.
They might not technically break the law but they would break convention. In the process they also symbolise a notable shift in the US from democracy to autocracy.
When the “no kings!” demonstrations took place in the US earlier this year, they reminded us of a key motivation for the declaration of independence.
A coin celebrating its 250-year anniversary may well symbolise its journey to demise.
Peter Edwell receives funding from the Australian Research Council.
More than 54,000 children aged under five in Gaza are suffering acute malnutrition, including more than 12,800 who are severely malnourished, according to a study published in The Lancet on Wednesday.
When more than 15% of the population experiences acute malnutrition, the World Health Organization classifies this as “very high” – its most severe category. In August, the overall rate of acute malnutrition among study participants in Gaza was 15.8%.
Rafah consistently had the highest acute malnutrition rate, across the 20-month study period to August 2025, reaching 32% of children in December 2024.
Acutely malnourished children are at higher risk of severe infections and premature death. If malnutrition becomes long term, the child may develop stunting (shortness for their age) and subsequent cognitive impairment.
A child with severe acute malnutrition is also up to 11 times more likely than a healthy child to die of common childhood illnesses such as pneumonia, the single largest infectious cause of death in children worldwide.
How was the study conducted?
The researchers assessed 219,783 children aged 6–59 months for acute malnutrition – also known as wasting – which reflects recent weight loss. This study size accounts for around 64% of children in Gaza in that age group.
It was conducted in 16 UN health centres and 78 medical points established in school shelters and tent encampments across the five local areas of Gaza.
According to the WHO, the gold standard of assessing the nutritional status of a child is to measure their weight (using standard hanging scales) and their height or length. It also recommends measuring arm circumference to detect acute malnutrition in community screening settings, as numerous studies have demonstrated this is an accurate way of detecting acute malnutrition.
The Lancet study measured the children’s height and weight, as well as their mid-upper arm circumference using a standard measuring tape developed by UNICEF.
However, a number of researchers have recommended increasing the diagnostic threshold, which is currently 125 mm, which would mean more children meet the threshold for malnutrition.
The researchers in Gaza calculated what is called the Z-score for each assessed child, as is standard practice. This is the number of standard deviations above or below the median of the WHO reference population. A Z-score between -2 and -3 represents moderate acute malnutrition and a Z-score of less than -3 is severe acute malnutrition.
What did the researchers find?
The monthly prevalence of acute malnutrition ranged from 5% to 7% between January and June 2024.
After around four months of severe aid restrictions, between September 2024 and mid-January 2025, the prevalence increased from 8.8% to 14.3%. The highest prevalence was seen in Rafah (32.2%).
After a six-week ceasefire and a substantial increase in the number of aid trucks entering Gaza, by March 2025, the prevalence of wasting had declined to 5.5%.
However, an 11-week blockade occurred from March to May 2025 and severely restricted entry of food, water, medicines, fuel and other essentials. By early August 2025, 15.8% of screened children were acutely malnourished, including 3.7% who were severely wasted. This equates to more than 54,600 children in need of treatment using ready-to-use therapeutic food – a paste containing high quantities of calories and other nutrients.
Boys were more likely to be malnourished than girls, which was consistent with the pre-war period. Studies across the globe have found malnutrition rates are usually higher in boys than girls.
Was the study well conducted?
This was a longitudinal (conducted over time, in this case 20 months) cross-sectional study, which means the researchers took their measurements at certain intervals (in this case, monthly).
The authors provide extensive details of the numbers of children included, in which local area, what kind of facility (a fixed medical centre or medical point), as well as age and sex.
Two-thirds of the participants were in Khan Younis and Middle governorates, with relatively low numbers in North Gaza and Rafah, which were highly affected by military activities.
The analysis was thorough, preceded by a data cleansing process which excluded values that were implausible. Standard statistical tests were applied to the data.
The paper was peer reviewed before publication.
What do the findings mean?
The Integrated Food Security Phase Classification, known as the IPC scale, defines famine as a situation in which at least one in five households has an extreme lack of food and faces starvation and destitution, resulting in extremely critical levels of acute malnutrition and death. The IPC uses the same classification of acute malnutrition as the WHO.
The IPC scale defines five phases of food insecurity. Famine (phase 5) is the highest phase of the scale, and is classified when an area has 20% of households facing extreme food shortage and 30% of children are acutely malnourished.
In late August 2025, the IPC released its fifth report on Gaza. It found for the period July 1 to August 15 2025, there was famine (phase 5) for the Gaza governorate and emergency (phase 4) for Deir al-Balah and Khan Younis. It was unable to adequately assess North Gaza because of insecurity.
The food insecurity situation in Gaza is among the worst in the world, comparable with the current situation in Sudan, Yemen and Haiti. It is a man-made disaster and can be reversed by urgent human action.
The Lancet study found spikes in acute malnutrition coincided with aid blockades. A ceasefire and a complete opening to international aid are fundamental to a resolution of the food crisis.
Michael Toole receives funding from the National Health and Medical Research Council..
Two decades after Timor-Leste gained its independence, the country is a complicated and qualified success story. Poverty and deep economic problems persist, but the country boasts a thriving democracy. Its ascension to the ASEAN regional bloc will come later this month.
As this milestone approaches, however, a senior official with oversight over the national intelligence agency has gone public with explosive claims that Timorese institutions are allegedly being bought by organised crime.
His concerns come after a recent UN report that describes in vivid detail a sophisticated attempt by figures linked to triad gangs in China and Southeast Asia to allegedly establish a base of operations in the Timorese region of Oecusse-Ambeno.
If the allegations are true, they could pose the one of the greatest tests for Timor-Leste in its short history. Is its democracy robust enough to confront the challenge?
Allegations of corruption
Agio Pereira is the Timorese minister of the Presidency of the Council of Ministers. He is one of the most powerful elected officials in his country.
On September 21, Pereira published on Facebook what he called A Manifesto for the Defence of Timor-Leste. In it, he claims to have
“undeniable and damning evidence” that US$45 million (A$68 million) has been brought (in some cases flown) into the country by “transnational criminal syndicates from Cambodia, Malaysia, Macau and Hong Kong”.
He says the money was allegedly used to influence regulatory bodies to grant “fraudulent licences” and set up “protected enclaves” where “illegal gambling, cyber-scam centres and human trafficking would be able to operate under state protection”.
He said the country faces a simple choice:
Will we be a sovereign nation governed by democratic laws and institutions, or will we become a criminal state owned by foreign mafia syndicates?
Pereira also listed numerous demands, including:
the revocation of any licences that may have been granted to criminal networks
government cooperation with international law enforcement to dismantle the networks
an investigation of all officials who have allegedly taken any money.
Pereira did not provide any evidence in the post to back up his claims, but especially given his status and oversight of the national intelligence service, many are taking his claims seriously.
In response to the allegations, President José Ramos-Horta told me via WhatsApp:
I always said Timor-Leste does not have homegrown organised crime. […] But Timor-Leste, being still a fragile country, is very attractive to organised crime from Asia.
I have full confidence in our authorities with support from Australian Federal Police and from Indonesian police in tackling the challenges by organised crime.
Prime Minister Xanana Gusmao also took a measured response to the allegations. He told local media Pereira would be given a chance to raise the issue with the government directly.
On October 1, he was given his chance, addressing a meeting of Timor-Leste’s Counsel of Ministers. This resulted in the swift approval of a draft resolution cancelling all existing licences granted for online gambling and betting operations and prohibiting any new licences from being issued.
But Pereira’s other key demand – an investigation into officials accused of taking money from organised crime syndicates – appears not to have been addressed.
Illegal gambling and scam centres have proliferated in recent years in “special economic zones” in Cambodia, Laos, Myanmar and the Philippines. The organised crime groups behind them are constantly looking for new bases of operations where local officials can be persuaded to look the other way, or lack the capacity to stop them.
Although Timor-Leste is small, it’s important due to its strategic location (just a 1.5-hour flight from Darwin) and the fact Australia and its allies are increasingly competing for influence there with China. Australia cannot afford to ignore any threat to the security of a fledgling democracy on its doorstep.
Pereira’s manifesto came in the wake of an August 25 raid on a suspected scam centre in Oecusse-Ambeno, where 30 foreign nationals from Indonesia, Malaysia and China were detained. The head of the regional government, Rogerio Lobato, was given notice two days later.
Oecusse, as it’s commonly known, is a rugged coastal exclave on the western half of Timor island, surrounded by Indonesia. Once extremely isolated, Oecusse was granted autonomy in 2014 and a special economic zone was established to spur foreign investment.
The report from the UN Office on Drugs and Crime in September described how organised crime groups took advantage of the region’s loose regulatory structures late last year to allegedly establish an “Oecusse Digital Centre”. It reads:
The Special Administrative Region of Oecusse-Ambeno (RAEOA), Timor-Leste appears to have already been targeted by criminal networks through FDI [foreign direct investment].
As Timor-Leste prepares to join ASEAN in October 2025, the reported infiltration of RAEOA and its national ID system by convicted cybercriminals poses a serious security risk.
The report notes that Timor-Leste shares “stark similarities” with the development of the scam industry in Cambodia, Laos and the Philippines, which have now become notorious hubs for cyber fraud, drug trafficking and human trafficking.
In his message to me, Ramos-Horta declined to address the allegations surfaced by the UN report, saying:
I know well the work of UN agencies. They should focus more on solid research and less on allegations against individuals because this is not their mandate.
In his manifesto, Pereira appears to suggest operations like the one recently raided in Oecusse are made possible through the bribery of Timorese officials. He says directly this influence is occurring on a scale that risks state capture.
Reactions to Pereira’s allegations
It’s unclear why Pereira chose to appeal directly to the people rather than take his concerns to others in the government.
Nelson Belo, director of the civil society and security monitoring organisation Fundasaun Mahein, criticised Pereira’s choice to go public. He said as a minister, he should “lead and act within the law”.
Belo’s group had also recently warned of the risks transnational organised crime groups could pose to the country.
Abel Pires, a former government minister and former member of Timor-Leste’s Council of Defence and Security, had a different view.
He reasoned that because “the problem may involve too many people within the system”, Pereira might have had no choice but to go public.
He also called the cancellation of gambling licences a positive step, but said there must be an independent investigation into Pereira’s allegations.
On the street, the allegations have fed into frustration with official greed and incompetence, which fuelled recent student demonstrations against government waste.
That a leading minister felt he needed to go public with the accusations to have them taken seriously by his own government is telling.
The potential subversion of Timor-Leste’s institutions by organised crime is a serious threat to the country’s security. Its government – as well as Australia’s – would do well to pay heed.
Michael Rose does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
On October 6 1995, at a scientific meeting in Florence, Italy, two Swiss astronomers made an announcement that would transform our understanding of the universe beyond our solar system. Michel Mayor and his PhD student Didier Queloz, working at the University of Geneva, announced they had detected a planet orbiting a star other than the Sun.
The star in question, 51 Pegasi, lies about 50 light years away in the constellation Pegasus. Its companion – christened 51 Pegasi b – was unlike anything written in textbooks about how we thought planets might look. This was a gas giant with a mass of at least half that of Jupiter, circling its star in just over four days. It was so close to the star (1/20th of Earth’s distance from the Sun, well inside Mercury’s orbit) that the planet’s atmosphere would be like a furnace, with temperatures topping 1,000°C.
The instrument behind the discovery was Elodie, a spectrograph that had been installed two years earlier at the Haute-Provence observatory in southern France. Designed by a Franco-Swiss team, Elodie split starlight into a spectrum of different colours, revealing a rainbow etched with fine dark lines. These lines can be thought of as a “stellar barcode”, providing details on the chemistry of other stars.
What Mayor and Queloz spotted was 51 Pegasi’s barcode sliding rhythmically back-and-forth in this spectrum every 4.23 days – a telltale signal that the star was being wobbled back and forth by the gravitational tug of an otherwise unseen companion amid the glare of the star.
After painstakingly ruling out other explanations, the astronomers finally decided that the variations were due to a gas giant in a close-in orbit around this Sun-like star. The front page of the Nature journal in which their paper was published carried the headline: “A planet in Pegasus?”
The discovery baffled scientists, and the question-mark on Nature’s front cover reflected initial scepticism. Here was a purported giant planet next to its star, with no known mechanism for forming a world like this in such a fiery environment.
While the signal was confirmed by other teams within weeks, reservations about the cause of the signal remained for almost three years before being finally ruled out. Not only did 51 Pegasi b become the first planet discovered orbiting a Sun-like star outside our Solar System, but it also represented an entirely new type of planet. The term “hot Jupiter” was later coined to describe such planets.
This discovery opened the floodgates. In the 30 years since, more than 6,000 exoplanets (the term for planets outside our Solar System) and exoplanet candidates have been catalogued.
Their variety is staggering. Not only hot but ultra-hot Jupiters with a dayside temperature exceeding 2,000 °C and orbits of less than a day. Worlds that orbit not one but two stars, like Tatooine from Star Wars. Strange “super-puff” gas giants larger than Jupiter but with a fraction of the mass. Chains of small rocky planets all piled up in tight orbits.
The discovery of 51 Pegasi b triggered a revolution and, in 2019, landed Mayor and Queloz a Nobel prize. We can now infer that most stars have planetary systems. And yet, of the thousands of exoplanets found, we have yet to find a planetary system that resembles our own.
The quest to find an Earth twin – a planet that truly resembles Earth in size, mass and temperature – continues to drive modern-day explorers like us to search for more undiscovered exoplanets. Our expeditions may not take us on death-defying voyages and treks like the past legendary explorers of Earth, but we do get to visit beautiful, mountain-top observatories often located in remote areas around the world.
We are members of an international consortium of planet hunters that built, operate and maintain the Harps-N spectrograph, mounted on the Telescopio Nazionale de Galileo on the beautiful Canary island of La Palma. This sophisticated instrument allows us to rudely interrupt the journey of starlight which may have been travelling unimpeded at speeds of 670 million miles per hour for decades or even millennia.
Each new signal has the potential to bring us closer to understanding how common planetary systems like our own may (or may not) be. In the background lies the possibility that one day, we may finally detect another planet like Earth.
The origins of exoplanet study
Up until the mid-1990s, our Solar System was the only set of planets humanity ever knew. Every theory about how planets formed and evolved stemmed from these nine, incredibly closely spaced data-points (which went down to eight when Pluto was demoted in 2006, after the International Astronomical Union agreed a new definition of a planet).
All of these planets revolve around just one star out of the estimated 10¹¹ (roughly 100 billion) in our galaxy, the Milky Way – which is in turn one of some 10¹¹ galaxies throughout the universe. So, trying to draw conclusions from the planets in our Solar System alone was a bit like aliens trying to understand human nature by studying students living together in one house. But that didn’t stop some of the greatest minds in history speculating on what lay beyond.
The ancient Greek philosopher Epicurus (341-270BC) wrote: “There is an infinite number of worlds – some like this world, others unlike it.” This view was not based on astronomical observation but his atomist theory of philosophy. If the universe was made up of an infinite number of atoms then, he concluded, it was impossible not to have other planets.
Epicurus clearly understood what this meant in terms of the potential for life developing elsewhere:
We must not suppose that the worlds have necessarily one and the same shape. Nobody can prove that in one sort of world there might not be contained – whereas in another sort of world there could not possibly be – the seeds out of which animals and plants arise and all the rest of the things we see.
In contrast, at roughly the same time, fellow Greek philosopher Aristotle (384-322 BC) was proposing his geocentric model of the universe, which had the Earth immobile at its centre with the Moon, Sun and known planets orbiting around us. In essence, the Solar System as Aristotle conceived it was the entire universe. In On the Heavens (350BC), he argued: “It follows that there cannot be more worlds than one.”
Such thinking that planets were rare in the universe persisted for 2,000 years. Sir James Jeans, one of the world’s top mathematicians and an influential physicist and astronomer at the time, advanced his tidal hypothesis of planet formation in 1916. According to this theory, planets were formed when two stars pass so closely that the encounter pulls streams of gas off the stars into space, which later condense into planets. The rareness of such close cosmic encounters in the vast emptiness of space led Jeans to believe that planets must be rare, or – as was reported in his obituary – “that the solar system might even be unique in the universe”.
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But by then, understanding of the scale of the universe was slowly changing. In the “Great Debate” of 1920, held at the Smithsonian Museum of Natural History in Washington DC, American astronomers Harlow Shapley and Heber Curtis clashed over whether the Milky Way was the entire universe, or just one of many galaxies. The evidence began to point to the latter, as Curtis had argued for. This realisation – that the universe contained not just billions of stars, but billions of galaxies each containing billions of stars – began to affect even the most pessimistic predictors of planetary prevalence.
In the 1940s, two things caused the scientific consensus to pivot dramatically. First, Jeans’ tidal hypothesis did not stand up to scientific scrutiny. The leading theories now had planet formation as a natural byproduct of star formation itself, opening up the potential for all stars to host planets.
Then in 1943, claims emerged of planets orbiting the stars 70 Ophiuchus and 61 Cygni c – two relatively nearby star systems visible to the naked eye. Both were later shown to be false positives, most likely due to uncertainties in the telescopic observations that were possible at the time – but nonetheless, it greatly influenced planetary thinking. Suddenly, billions of planets in the Milky Way was considered a genuine scientific possibility.
For us, nothing highlights this change in mindset more than an article written for the Scientific American in July 1943 by the influential American astronomer Henry Norris Russell. Whereas two decades earlier, Russell had predicted that planets “should be infrequent among the stars”, now the title of his article was: “Anthropocentrism’s Demise. New Discoveries Lead to the Probability that There Are Thousands of Inhabited Planets in our Galaxy”.
Strikingly, Russell was not merely making a prediction about any old planets, but inhabited ones. The burning question was: where were they? It would take another half-century to begin finding out.
The Harps-N spectrograph is mounted on the Telescopio Nazionale de Galileo (left) in La Palma, Canary Islands. lunamarina/Shutterstock
How to detect an exoplanet
When we observe myriad stars through La Palma’s Italian-built Galileo telescope using our Harps-N spectrograph, it is amazing to consider how far we have come since Mayor and Queloz announced their discovery of 51 Pegasi b in 1995. These days, we can effectively measure the masses of not just Jupiter-like planets, but even small planets thousands of light years away. As part of the Harps-N collaboration, we have had a front-row seat since 2012 in the science of small exoplanets.
Another milestone in this story came four years after the 51 Pegasi b discovery, when a Canadian PhD student at Harvard University, David Charbonneau, detected the transit of a known exoplanet. This was another hot Jupiter, known as HD209458b, also located in the Pegasus constellation, about 150 light years from Earth.
Transit refers to a planet passing in front of its star, from the perspective of the observer, momentarily making the star appear dimmer. As well as detecting exoplanets, the transit technique enables us to measure the radius of the planet by taking many brightness measurements of a star, then waiting for it to dim due to the passing planet. The extent of blocked starlight depends on the radius of the planet. For example, Jupiter would make the Sun 1% dimmer to alien observers, while for Earth, the effect would be a hundred times weaker.
In all, four times more exoplanets have now been discovered using this transit technique compared with the “barcode” technique, known as radial velocity, that the Swiss astronomers used to spot the first exoplanet 30 years ago. It is a technique that is still widely used today, including by us, as it can not only find a planet but also measure its mass.
A planet orbiting a star exerts a gravitational pull which causes that star to wobble back and forth – meaning it will periodically change its velocity with respect to observers on Earth. With the radial velocity technique, we take repeated measurements of the velocity of a star, looking to find a stable periodic wobble that indicates the presence of a planet.
These velocity changes are, however, extremely small. To put it in perspective, the Earth makes the Sun change its velocity by a mere 9cm per second – slower than a tortoise. In order to find planets with the radial velocity technique, we thus need to measure these small velocity changes for stars that are many many trillions of miles away from us.
The state-of-the-art instruments we use are truly an engineering feat. The latest spectrographs, such as Harps-N and also Espresso, can accurately measure velocity shifts of the order of tenths of centimetres per second – although still not sensitive enough to detect a true Earth twin.
But whereas this radial velocity technique is, for now, limited to ground-based observatories and can only observe one star at the time, the transit technique can be employed in space telescopes such as the French Corot (2006-14) and Nasa’s Kepler (2009-18) and Tess (2018-) missions. Between them, space telescopes have detected thousands of exoplanets in all their diversity, taking advantage of the fact we can measure stellar brightness more easily from space, and for many stars at the same time.
Despite the differences in detection success rate, both techniques continue to be developed. Applying both can give the radius and mass of a planet, opening up many more avenues for studying its composition.
To estimate possible compositions of our discovered exoplanets, we start by making the simplified assumption that small planets are, like Earth, made up of a heavy iron-rich core, a lighter rocky mantle, some surface water and a small atmosphere. Using our measurements of mass and radius, we can now model the different possible compositional layers and their respective thickness.
This is still very much a work in progress, but the universe is spoiling us with a wide variety of different planets. We’ve seen evidence of rocky worlds being torn apart and strange planetary arrangements that hint at past collisions. Planets have been found across our galaxy, from Sweeps-11b in its central regions (at nearly 28,000 light years away, one of the most distant ever discovered) to those orbiting our nearest stellar neighbour, Proxima Centauri, which is “only” 4.2 light years away.
Illustration of Proxima b, one of the exoplanets orbiting the nearest star to our Sun, Proxima Centauri. Catmando/Shutterstock
Searching for ‘another Earth’
In early July 2013, one of us (Christopher) was flying out to La Palma for my first “go” with the recently commissioned Harps-N spectrograph. Keen not to mess up, my laptop was awash with spreadsheets, charts, manuals, slides and other notes. Also included was a three-page document I had just been sent, entitled: Special Instructions for ToO (Target of Opportunity).
The first paragraph stated: “The Executive Board has decided that we should give highest priority to this object.” The object in question was a planetary candidate thought to be orbiting Kepler-78, a star a little cooler and smaller than our Sun, located about 125 light years away in the direction of the constellation Cygnus.
A few lines further down read: “July 4-8 run … Chris Watson” with a list of ten times to observe Kepler-78 – twice per night, each separated by a very specific four hours and 15 minutes. The name above mine was Didier Queloz’s (he hadn’t been awarded his Nobel prize yet, though).
This planetary candidate had been identified by the Kepler space telescope, which was tasked with searching a portion of the Milky Way to look for exoplanets as small as the Earth. In this case, it had identified a transiting planet candidate with an estimated radius of 1.16 (± 0.19) Earth radii – an exoplanet not that much larger than Earth had potentially been spotted.
I was in La Palma to attempt to measure its mass which, combined with the radius from Kepler, would allow the density and possible composition to be constrained. I wrote at the time: “Want 10% error on mass, to get a good enough bulk density to distinguish between Earth-like, iron-concentrated (Mercury), or water.”
In all, I took ten out of our team’s total of 81 exposures of Kepler-78 in an observing campaign lasting 97 days. During that time, we became aware of a US-led team who were also looking for this potential planet. In true scientific spirit, we agreed to submit our independent findings at the same time. On the specified date. Like a prisoner swap, the two teams exchanged results – which agreed. We had, within the uncertainties of our data, reached the same conclusion about the planet’s mass.
Its most likely mass came out as 1.86 Earth masses. At the time, this made Kepler-78b the smallest extrasolar planet with an accurately measured mass. The density was almost identical to that of Earth’s.
But that is where the similarities to our planet ended. Kepler-78b has a “year” that lasts only 8.5 hours, which is why I had been instructed to observe it every 4hr 15min – when the planet was at opposite sides of its orbit, and the induced “wobble” of the star would be at its greatest. We measured the star wobbling back and forth at about two metres per second – no more than a slow jog.
Kepler-78b’s short orbit meant its extreme temperature would cause all rock on the planet to melt. It may have been the most Earth-like planet found at the time in terms of its size and density, but otherwise, this hellish lava world was at the very extremes of our known planetary population.
Illustration of the Kepler-78b ‘lava world’ – similar in size and density to Earth. simoleonh/Shutterstock
In 2016, the Kepler space telescope made another landmark discovery: a system with at least five transiting planets around a Sun-like star, HIP 41378, in the Cancer constellation. What made it particularly exciting was the location of these planets. Where most transiting planets we have spotted are closer to their star than Mercury is to the Sun (due to our detection capabilities), this system has at least three planets beyond the orbital radius of Venus.
Having decided to use our Harps-N spectrograph to measure the masses of all five transiting planets, it became clear after more than a year of observing that one instrument would not be enough to analyse this challenging mix of signals. Other international teams came to the same conclusion and, rather than compete, we decided to come together in a global collaboration that holds strong to this day, with hundreds of radial velocities gathered over many years.
We now have firm masses and radii for most of the planets in the system. But studying them is a game of patience. With planets much further away from their host star, it takes much longer before there is a new transit event or the periodic wobble can be fully observed. We thus need to wait multiple years and gather lots of data to gain insight in this system.
The rewards are obvious, though. This is the first system that starts resembling our Solar System. While the planets are a bit larger and more massive than our rocky planets, their distances are very similar – helping us to understand how planetary systems form in the universe.
The holy grail for exoplanet explorers
After three decades of observing, a wealth of different planets have emerged. We started with the hot Jupiters, large gas giants close to their star that are among the easiest planets to find due to both deeper transits and larger radial velocity signals. But while the first tens of discovered exoplanets were all hot Jupiters, we now know these planets are actually very rare.
With instrumentation getting better and observations piling up, we have since found a whole new class of planets with sizes and masses between those of Earth and Neptune. But despite our knowledge of thousands of exoplanets, we still have not found systems truly resembling our solar system, nor planets truly resembling Earth.
It is tempting to conclude this means we are a unique planet in a unique system. While this still could be true, it is unlikely. The more reasonable explanation is that, for all our stellar technology, our capabilities of detecting such Earth-like planets are still fairly limited in a universe so mind-bogglingly vast.
The holy grail for many exoplanet explorers, including us, remains to find this true Earth twin – a planet with a similar mass and radius as Earth’s, orbiting a star similar to the Sun at a distance similar to how far we are from the Sun.
While the universe is rich in diversity and holds many planets unlike our own, discovering a true Earth twin would be the best place to start looking for life as we know it. Currently, the radial velocity method – as used to find the very first exoplanet – remains by far the best-placed method to find it.
Thirty years on from that Nobel-winning discovery, pioneering planetary explorer Didier Queloz is taking charge of the very first dedicated radial velocity campaign to go in search of an Earth-like planet.
A major international collaboration is building a dedicated instrument, Harps3, to be installed later this year at the Isaac Newton Telescope on La Palma. Given its capabilities, we believe a decade of data should be enough to finally discover our first Earth twin.
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Christopher Watson receives funding from the Science and Technology Facilities Council (STFC).
Annelies Mortier receives funding from the Science and Technology Facilities council (STFC) and UK Research and Innovation (UKRI).
Tilly Norwood officially launched her acting career this month at the Zurich Film Festival.
She first appeared in the short film AI Commissioner, released in July. Her producer, Eline Van der Velden, claims Norwood has already attracted the attention of multiple agents.
But Norwood was generated with artificial intelligence (AI). The AI “actor” has been created by Xicoia, the AI branch of the production company Particle6, founded by the Dutch actor-turned-producer Ven der Velden. And AI Commissioner is an AI-generated short film, written by ChatGPT.
A post about the film’s launch on Norwood’s Facebook page read,
I may be AI generated, but I’m feeling very real emotions right now. I am so excited for what’s coming next!
The reception from the industry has been far from warm. Actors – and audiences – have come out in force against Norwood.
So, is this the future of film, or is it a gimmick?
‘Tilly Norwood is not an actor’
Norwood’s existence introduces a new type of technology to Hollywood. Unlike CGI (computer generated imagery), where a performer’s movements are captured and transformed into a digital character, or an animation which is voiced by a human actor, Norwood has no human behind her performance. Every expression and line delivery is generated by AI.
Norwood has been trained on the performances of hundreds of actors, without any payment or consent, and draws on the information from all those performances in every expression and line delivery.
Her arrival comes less than two years after the artist strikes that brought Hollywood to a stand-still, with AI a central issue to the disputes. The strike ended with a historic agreement placing limitations around digital replicas of actors’ faces and voices, but did not completely ban “synthetic fakes”.
SAG-AFTRA, the union representing actors in the United States, has said:
To be clear, ‘Tilly Norwood’ is not an actor; it’s a character generated by a computer program that was trained on the work of countless professional performers – without permission or compensation.
Additionally, real actors can set boundaries and are protected by agents, unions and intimacy coordinators who negotiate what is shown on screen.
Norwood can be made to perform anything in any context – becoming a vessel for whatever creators or producers choose to depict.
This absence of consent or control opens a dangerous pathway to how the (digitally reproduced) female body may be represented on screen, both in mainstream cinema, and in pornography.
Is it art?
We consider creativity to be a human quality. Art is generally understood as an expression of human experience. Norwood’s performances do not come from such creativity or human experience, but from a database of pre-existing performances.
All artists borrow from and are influenced by predecessors and contemporaries. But that human influence is limited by time, informed by our own experiences and shaped by our unique perspective.
AI has no such limits: just look at Google’s chess-playing program AlphaZero, which learnt by playing millions of games of chess, more than any human can play in a life time.
Norwood’s training can absorb hundreds of performances in a way no single actor could. Particle6 Productions
Norwood’s training can absorb hundreds of performances in a way no single actor could. How can that be compared to an actor’s performance – a craft they have developed throughout their training and career?
Van der Velden argues Norwood is “a new tool” for creators. Tools have previously been a paintbrush or a typewriter, which have helped facilitate or extend the creativity of painting or writing.
Here, Norwood as the tool performs the creative act itself. The AI is the tool and the artist.
Will audiences accept AI actors?
Norwood’s survival depends not on industry hype but on audience reception.
So far, humans show a negative bias against AI-generated art. Studies across art forms have shown people prefer works when told they were created by humans, even if the output is identical.
We don’t know yet if that bias could fade. A younger generation raised on streaming may be less concerned with whether an actor is “real” and more with immediate access, affordability or how quickly they can consume the content.
If audiences do accept AI actors, the consequences go beyond taste. There would be profound effects on labour. Entry- and mid-level acting jobs could vanish. AI actors could shrink the demand for whole creative teams – from make-up and costume to lighting and set design – since their presence reduces the need for on-set artistry.
Economics could prove decisive. For studios, AI actors are cheaper, more controllable and free from human needs or unions. Even if audiences are ambivalent, financial pressures could steer production companies towards AI.
The bigger picture
Tilly Norwood is not a question of the future of Hollywood. She is a cultural stress-test – a case study in how much we value human creativity.
What do we want art to be? Is it about efficiency, or human expression? If we accept synthetic actors, what stops us from replacing other creative labour – writers, musicians, designers – with AI trained on their work, but with no consent or remuneration?
We are at a crossroads. Do we regulate the use of AI in the arts, resist it, or embrace it?
Resistance may not be realistic. AI is here, and some audiences will accept it. The risk is that in choosing imitation over human artistry, we reshape culture in ways that cannot be easily reversed.
Amy Hume does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
