The Night Sky Is In Danger And Astronomers Are Stepping Up To Protect It

The International Astronomical Union (IAU) has passed a resolution to strengthen the work it does in protecting the Dark and Quiet Sky both on the ground and in space. That the resolution would pass was obvious – you wouldn’t expect turkeys to vote for Christmas – but it matters greatly in showing the commitment of the IAU to protecting the sky, not just for astronomers but for all of us. It is, after all, a shared heritage of humankind.

It is for this reason that the resolution was on the table for the 32nd General Assembly of the IAU, the first one that took place in Africa. Among the many sessions, there have been workshops on the topic of Dark and Quiet skies. Threats to the sky are multiple – the most common on the ground is light pollution.

“A problem for us with light pollution on the ground is the ongoing world transition to LED technology, which has made light at night very inexpensive to consume,” Dr John Barentine, the Executive Officer and Principal Consultant at Dark Sky Consulting , told IFLScience. “In the last decade, the brightness of the night sky has been rising around the world on the order of about 10 percent per year on average.”

We are still trying to develop and refine our messaging to emphasise that there is a win-win – that it is possible to have responsibly designed, effective light while also minimising light pollution.

Carol Nyaguthii

The transition to LED has been good in terms of energy consumption as the bulbs consume much less energy than filament bulbs. But it has meant that it is now possible to illuminate areas all night long, including places that weren’t really illuminated, simply because it’s very cheap. A common example is floodlights in an industrial parking lot, even when there’s no one on the premises.

Light pollution impacts astronomy and our enjoyment of the night sky , but it also impacts our body’s natural rhythms leading to sleeplessness. It also affects animals, plants, and other living organisms that rely on the sky and darkness to live and thrive.

“One of the biggest challenges has been raising awareness about the importance of dark sky preservation. While people more intuitively understand how light pollution affects astronomy, its effects on biodiversity, health, and heritage are harder to communicate,” Carol Nyaguthii, secretary of DarkSky Kenya , told IFLScience.

In many countries in the Global North, the work of Dark Sky initiatives is focused on reversing the damage and making better choices for the future. Places like Kenya, where electrification is still expanding, are about to show that it is possible to bring lighting without having to compromise the protection of the night sky.

“We are still trying to develop and refine our messaging to emphasise that there is a win-win – that it is possible to have responsibly designed, effective light while also minimising light pollution,” Nyaguthii explained.

Clever design, timers, motion sensors, and different colors are some of the ways that light pollution is mitigated. However, part of the problem does not come from the ground, but from satellites .

There are a lot more satellites in space than ever before. The megaconstellations of satellites, with hundreds if not thousands of individual orbiting objects, are changing the sky dramatically. This impacts astronomers who can’t perform observations without streaks, but if they add to overall brightness , even designated dark areas on Earth are not safe.

As of June 2024, there were 11,780 satellites in orbit and 6,050 of them were from SpaceX’s megaconstellation Starlink. The company owned by Elon Musk aims to at least double the number and ideally get to six times as many satellites in space. They are not alone in this endeavor. Many private and public organizations are planning similar numbers of objects in space.

These satellites bring not just light, they also send radio waves down to places on Earth where there is usually very little radio frequency. Scientists want to make sure progress in access to space doesn’t come at the cost of our ability to study the universe in the first place.

“The sky is a resource, I think, that's available to everybody. And there's so much out there in astronomy that we don't yet know. The increased number of satellites poses a risk to our ability to actually see and learn more things. And I think we can try and cooperate together to keep the sky dark, to keep it quiet, so that we're still able to do observations and do science,” Dr Wendy Williams , a scientist for the SKA Observatory, told IFLScience.

With 300,000 satellites expected to be in orbit over the course of the next decade, the crucial issue is that there is little regulation at national and international levels to keep light and radio pollution to a minimum. As an example, in the US, the Federal Communications Commission requires operators to have a coordination agreement with the National Science Foundation to keep light pollution to a minimum.

“It's mandatory to have this coordination agreement, but it doesn’t actually mandate any specific limit or threshold or brightness requirement,” Dr Andrew Williams , from the European Southern Observatory (ESO), told IFLScience. “So companies can make good faith efforts. But presumably, they could say: ‘Well, look, we tried as hard as we can, it cost us a huge amount of effort, but sorry, that’s the best we can do.’ It’s not clear what is actually going to happen in that situation.”

Still, all the people we interviewed at the General Assembly regarding the Dark and Quiet Sky have stressed that private companies are engaging and listening to the concern. They are willing to change satellite designs, turn off emitters over specific regions, and more.

“We don't want to roll back any progress,” Dr Barentine explained. “The satellite operators have a right to be in space, just as we have a right to access space for astronomy purposes. So we're actively working with them to try to find a solution that is as much of an agreement on the basics as we can reach to where they're able to conduct their activities without causing undue interference to what we're doing.”

I hope there will be some regulation for the protection of the dark and quiet sky.

Prof. Roberto Ragazzoni

This sentiment is echoed by Dr Lewis Ball , the Director of Operations for the SKA Organisation. SKA Observatory will be a revolutionary radio astronomy facility spread across South Africa and Australia, and a quiet sky is paramount for its quest to answer some of the biggest mysteries of the universe. Companies are willing to listen to organizations trying to protect the sky, but this is done on a one-to-one basis. What happens when there are dozens?

“One of the challenges that we face though is that at the moment there's one major and small number of other operators.  But as that grows, the one-to-one interaction becomes simply too hard to manage. We can't be engaging with 20 or 25 or 50 different operators. So we have to look at the regulatory side and have some input to that as well,” Dr Ball explained.

This is why clear rules and regulations are key for the long-term protection of the night sky and the safe operation of satellites in space. Things are moving slowly but there’s reason to hope for more in the near future.

“The European Space Agency has mandatory space debris mitigation standards and they're going through a process now of updating these,” Dr Williams told IFLScience. “They have the Clean Space program and we've managed to get dark and quiet skies as an item that's now part of this Space Debris Mitigation Standard.”

The risk of space debris is a serious one and the space industry is paying attention to those requirements. Adding Dark and Quiet Sky protection makes it easier to know what private companies should do. Still, the constant request we hear is for clear regulations.

“The most precious resource for astronomers Is the sky. This remained unchanged for millennia. But it is no longer the case. The sky is threatened by light pollution and satellite constellation, among other things. The IAU, together with its partner, NFS Noirlab, the SKAO, under the leadership of Piero Benvenuti, and with the support of several concerned countries is raising the issue at the highest political level including the [United Nations],” Willy Benz , incoming IAU president, said during a gala at the Italian Embassy in Cape Town attended by IFLScience.

This is also echoed by Professor Roberto Ragazzoni , the president of the Italian National Institute for Astrophysics and chair of the next IAU General Assembly that will take place in Rome in August 2027.

“I hope there will be some regulation for the protection of the dark and quiet sky,” Ragazzoni told us. “Especially on the radio side, we want to protect those special areas where today we are building, SKA or LOFAR or other telescopes.”

Dr Williams too, who is ESO's Representative to the United Nations Committee on the Peaceful Uses of Outer Space, is looking at the highest international levels for eventual regulation. “What we hope for in the long run is that the UN committee will make this a bit more formalized and will start the process of developing some kind of principles of protection of the dark and quiet skies.”