Most of the time, cities go dark within minutes of sunset. As construction crews turn off their tools for the night, streetlights come on in neighbourhoods. As the last rays of sunlight go down, solar farms stop making electricity. For most of human history the change from day to night has happened in the same way all over the world.
But the sky above Earth has been changing. There are thousands of satellites in low Earth orbit now, and long-exposure pictures of the Milky Way often show bright streaks crossing telescope pictures. Astronomers have started to keep track of how these spacecraft change the way we see faint stars and faraway galaxies. The night sky has already changed in some places because there are more satellites.
A new company in California wants satellites to do more after the sun goes down. Reflect Orbital is working on spacecraft that have big mirrors on them that will send sunlight down to the ground. The idea would let certain places get more light even after it gets dark.
Early plans say that thousands of satellites will form a constellation that will reflect sunlight toward Earth for short periods of time. The goal is to make useful daylight last longer for some activities, like making solar power or working at night. The proposal has already caught the attention of astronomers and environmental researchers, even though the technology is still in the testing phase.
Reflect Orbital Suggests Thousands of Satellites That Reflect Sunlight
Reflect Orbital’s plan is to send up a group of satellites with big mirrors on them. Early plans called for as many as 4,000 satellites to be in low Earth orbit. Each spacecraft would have a reflective surface that would send sunlight to a specific area on Earth. To control where the light hits, the mirror would move and tilt.
In the future, the mirror could be about 55 meters wide. The spacecraft would tilt the reflector so that the light from the sun hits the surface and travels toward the ground. The system only works in places that are already dark, while the satellite stays lit up by the Sun. The spacecraft can send sunlight down for a short time from that position.
The mirrors could be about 55 meters wide in the future. The satellite moves the mirror so that the light from the sun hits the reflective surface and goes toward Earth.
The mirrors could be about 55 meters wide in the future. The satellite angles the mirror so that the light from the sun hits the reflective surface and travels toward Earth. Thanks to Reflect Orbital
Eärendil-1 is the first step in testing the idea. When the spacecraft reaches orbit, it will release a square reflector that is about 18 by 18 meters in size. The satellite would be about 600 kilometres above the Earth’s surface. During each pass, it would send sunlight to certain places for a few minutes.
Engineers want to see how well the mirror can aim light that is reflected off of it during the mission. Sensors on the ground would check the brightness and coverage of each attempt to light up. These observations would help figure out if the system can reliably hit a certain area. The results would help the technology grow in the future.
How sunlight that bounces off of things would get to the ground
The suggested system depends on a path called a sun-synchronous orbit Satellites in this orbit move along the line that separates the light and dark sides of the planet. The spacecraft can stay in the sun even when the ground below has become dark because of this positioning. This shape lets the mirrors send sunlight to dark places.
The light that is reflected would not make a narrow spotlight The reflected beam spreads out as it goes through the atmosphere because the Sun looks like a disc in the sky. Instead of a concentrated beam this spreading makes a wider patch of light. The outcome would be a short brightening of some parts of the landscape.
Early models show that the lit-up area could be about 5 to 6 kilometres wide. People in that area might see the sky get brighter as the satellite goes by. During the reflection period the brightness might be brighter than natural moonlight. But the effect would only last a few minutes before the satellite moved along its path.
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Reflect Orbital says that the mirrors would move away from Earth after each pass. This step is meant to stop unwanted reflections from happening after the light period is over. The company says that the control system would keep stray light to a minimum outside of scheduled operations.
Astronomers are worried about how bright satellites are getting.
Researchers who study the night sky are worried about the proposal. Even regular satellites can get in the way of astronomical observations. When sunlight hits the surfaces of spacecraft, it can make bright streaks in telescope images. During long exposures, these streaks can go all the way across the field of view.
Dr. Alejandro S. Borlaff at NASA Ames Research Center led a study that looked at how satellite constellations affect telescope data. The study, which was published in the journal Nature looked at how reflected light from satellites messes up pictures taken by sensitive instruments. Astronomers often look for very faint things in deep space. Even short thoughts can get in the way of those observations.
Simulated Effects of Satellite Trails in Hubble, Spherex, Xuntian, and Arrakihs
Simulated effects of satellite trails in Hubble, SPHEREx, Xuntian, and ARRAKIHS. Credit NASA Borlaff, Marcum, Howell (Nature, 2025)
In the past few years, the number of satellites has grown quickly. In 2019, there were about 2,000 active satellites in orbit. By 2025, that number was expected to rise to about 15,000 Long-term forecasts say that hundreds of thousands of satellites could eventually fill low Earth orbit. Researchers are already looking into how this growth affects what they see.
Researchers say that satellites that are meant to reflect sunlight could make these problems worse. Some math shows that a big mirror satellite could look a lot brighter than the full moon when it is directly above. Reflections that strong could make the background brightness higher over large areas of the sky.
Ecosystems can also be affected by artificial light at night. Many animals depend on the natural darkness to help them with things like migrating or eating. Researchers who study the environment have shown how bright lights at night mess up those patterns. More light sources in orbit could make light pollution worse around the world.
DarkSky International and other groups keep an eye on how artificial light spreads around the world. Scientists who study nighttime lighting also look at how it affects people’s circadian rhythms, which control sleep cycles and hormone production. So, changes in nighttime lighting can be bad for both people and animals.
Another worry is that there is already a lot of hardware circling the Earth. Adding thousands of more spacecraft would make traffic in low Earth orbit worse, where satellites share space with pieces of space junk. Even tiny bits of debris move very quickly. Collisions can break satellites or make more debris.
The next big step is the demonstration satellite which is coming up soon. If the Eärendil-1 mission goes well, it will see if satellites can reliably bounce sunlight back to Earth during controlled orbital passes. The results will show if the Reflect Orbital idea can move on to its second test mission.
