Rescuing the stars

What are we doing to protect the night sky?

10 September 2021
What you’ll discover in this blog post:
  • How certain human activities endanger the night sky
  • What is the Committee on the Peaceful Uses of Outer Space and ESO’s role in it
  • How viewing astronomy as a space activity can help us protect the night sky
The starry sky is one of humanity’s most important heritages, an endless source of cultural, social and scientific inspiration over the millenia. Yet light pollution and increasing low-orbit space activity are putting this heritage at risk. The astronomical community, including ESO, have been taking actions to preserve the night sky. Now, Andrew Williams and Giuliana Rotola, external relations officer and former research intern at ESO respectively, are implementing a new idea to protect our view of the stars.

An endangered treasure

There are many things in life we take for granted without realising they might not be there forever. The starry night sky and ground-based astronomy are two of them. Like for the last survivors of a disappearing species, we witness the relentless shrinking of the natural habitat from where we can admire them.

The progressive loss of the starry sky and the increasing difficulty to perform some astronomical observations from the ground are a self-inflicted wound. Light pollution from our ever expanding cities and low-orbit satellite internet constellations, which can interfere with optical and radio observatories, degrade our view of the cosmos.


Illustration of how sunlit satellites can be seen from the ground at night. After sunset observers would see satellites towards the west, while those in the east would be within the Earth’s shadow. The opposite happens before sunrise.
Credit: ESO/L. Calçada



Simulation of the number of illuminated satellites from various megaconstellations visible over ESO’s VLT throughout the night. Yellow dots are illuminated satellites and gray ones are in the shadow.
Credit: O. Hainaut/ESO


"We need to find the balance between the freedom of access to space and the exploration of space."

“The human degradation of the outer space environment has been a problem since the ‘60s, with the Project West Ford, when a belt of millions of copper wires was to be sent around the Earth to create a global communication system,” says Giuliana Rotola, in her role as Space Law and Policy Project Group Co-lead at the Space Generation Advisory Council. “In space there is freedom of access, so every activity is in principle acceptable. It is different from airspace, as there is no jurisdiction or sovereignty, and we need to find the balance between the freedom of access to space and the exploration of space.”

It is paradoxical that ground-based astronomy is experiencing an unprecedented era of discoveries and technological development and, at the same time, it is threatened as never before. Space telescopes are less affected by these issues, but they only complement ground-based telescopes and can’t fully replace them. [1] Fortunately, the astronomical community is already taking measures to preserve the starry night, supporting light pollution control and working with satellite companies to mitigate the effects of their constellations. But how can we protect the sky at a more fundamental level?

United for the stars

One successful attempt to raise awareness about the importance of the night sky and astronomy was the effort by the International Astronomical Union (IAU), with support from ESO among others, to have the United Nations (UN) recognise 2009 as the International Year of Astronomy. The initiative celebrated the 400th anniversary of Galileo pointing the telescope to the sky for the first time — a simple gesture that changed humanity forever.

But not all attempts have been successful. The request to UNESCO made by the IAU to have the night sky recognised and hence protected as a world heritage proved to be unfeasible, for only Earth-based sites can be labelled as world heritages.

Andrew Williams at the June 2019 session of COPUOS
Andrew Williams at the June 2019 session of COPUOS.
Credit: A. Williams
Giuliana Rotola
Giuliana Rotola at the 2019 graduation ceremony of the Master of Space Studies Program of the International Space University.
Credit: G. Rotola

Following up on this unsuccessful attempt, in 2017 the IAU, ESO and other organisations decided to make their next move directly at the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS).

"It´s critical to be a member of COPUOS because that´s where the discussion about international law in space happens."

“COPUOS is a child of the Cold War,” says Andrew Williams, External Relations Officer at ESO. “After the Sputnik was launched in the 50s, there was this fear that space could become the next zone of conflict between the East and the West. COPUOS started as an ad-hoc committee under the UN General Assembly, but eventually it was set up as a permanent body with the basic mandate to stimulate international cooperation in the peaceful uses of outer space.”

Together with other organisations, such as the IAU, the European Space Agency and the European Union, ESO is a permanent observer at COPUOS. “As a permanent observer, you do not have the same rights as a member state, so you can’t raise an agenda item and you can’t vote,” explains Andrew, who represents ESO at COPUOS. “But for any kind of important space organisation it's critical to be a member of COPUOS because that's where the discussion about international law in space happens. By being there, we can advocate for astronomy to policy makers.”

The new proposal by the IAU made at COPUOS was successful, leading to the “Dark and quiet skies” project. The initiative will culminate in a conference looking at the protection of the night sky, organised by the IAU, the United Nations Office for Outer Space Affairs (UN OOSA) and the host country Spain in La Palma in October 2021. The event follows up on a previous conference organised in La Palma in 2017, on the 10th anniversary of the Starlight Declaration in Defence of the Night Sky and the Right to Starlight. Its main outcome will be a set of guidelines for governments and companies on how to reduce the detrimental impact of modern technology on astronomy, a document which will then be presented to the world governments at COPUOS.

The “Dark and quiet skies” project is a very promising initiative, but Andrew felt that we should move beyond guidelines and establish a legal framework recognised by international governments. And one day he had an idea: to ensure stronger protection, we should look at ground-based astronomy as a way to explore space.

The key: astronomy as a space activity

“Astronomy is a space activity in my view,” says Andrew, “and I would say it’s currently the main way we get to explore space, because you can't go and visit every single planet and every single minor body in the solar system: the main way that this is done is through astronomical telescopes.”

But there is much more to astronomy as a space activity, as Andrew summarised in a dedicated post. “Astronomy supports many critical functions of space activities, from tracking spacecraft to providing critical scientific observations to support space missions. And in terms of capacity building, with data archives, it is an important way for developing countries to experience space, often acting as a gateway to develop a national space capability.”

And last but not least, “with the International Asteroid Warning Network, astronomers can warn us about one of the few natural disasters that we can actually do something about. For example, we are using ESO’s Very Large Telescope in Chile for 30 hours a semester to track threatening asteroids and refine their orbits,” concludes Andrew.

Andrew’s idea was that, by looking at astronomy as a space activity, it could be possible to protect it under the Outer Space Treaty, the document governing the use of outer space developed by COPUOS and adopted by the UN General Assembly in 1967.

"Astronomy, even when ground-based, is fundamental for the exploration and use of outer space."

"The Outer Space Treaty is kind of a constitution for space activities,” explains Giuliana. “It provides the fundamental principles that are regulating the use and exploration of outer space. In particular, that everyone should be able to explore and investigate it, and that this should happen for the benefit and interest of all countries. And astronomy, even when ground-based, is fundamental for the exploration and use of outer space and enables other space activities, and so it should fall under its scope and be protected by its principles.”

Now that the idea was there, what was missing was a formalised set of arguments to convey it. To tackle this, Giuliana joined forces with Andrew, spending some months at ESO to bring their different backgrounds together: Andrew’s knowledge of astronomy and Giuliana’s expertise on space law.

“It is a problem that people with different compartmental knowledge often do not get together, so lawyers work with lawyers and astronomers work with astronomers,” says Giuliana. “But an interdisciplinary perspective is very important, because you cannot address the problem of the protection of astronomy just by knowing astronomy, you need to know the legal framework, and you cannot do it just by knowing the legal framework, you need to understand how space works.”

And hard work paid off, resulting in the publication of a dedicated paper outlining the proposal and the supporting arguments. “It's probably not going to result in any kind of immediate changes, but I like to think of it as a seed, that by going to COPUOS and talking about this will grow in many different people’s minds,” says Andrew.

"The night sky connects humanity [...] Without it, we would be even more divided."

A starless humanity?

Andrew and Giuliana’s story is a new tile in the puzzle of the preservation of the night sky and astronomy. And the risk we are facing naturally leads to the question of how a humanity without astronomy would be.

“It's hard to imagine because we've never experienced it,” says Andrew. “But we would probably have a very, very different perspective on life and our place in the world. And then there’s the search for life: in the same way the Copernican and Galilean revolution was a massive shift in culture, to know that there's life out there somewhere would represent one of the greatest changes in humanity.”

“On one side, astronomy can prevent the end of our civilization by warning us about dangerous asteroids, and on the other side it can support its flourishing beyond Earth,” adds Giuliana. “Moreover, the night sky connects humanity as it is the same for different populations. Without it, we would be even more divided.”

Notes

[1] Space telescopes have certain advantages over ground-based ones, such as being unaffected by atmospheric turbulence or light pollution, and observing at certain wavelengths blocked by the atmosphere. But they are not without problems: they are expensive, they impose tight constraints on the size and complexity of the instruments onboard them, and can’t be easily fixed or upgraded.

Biography Giulio Mazzolo

Giulio Mazzolo is a science journalism intern at ESO. Before starting a career in science communication, he completed a PhD in astrophysics from the Max Planck Institute for Gravitational Physics in Hannover (Germany) and has been a member of the LIGO Scientific Collaboration.

Send us your comments!
Subscribe to receive news from ESO in your language
Accelerated by CDN77
Terms & Conditions
Cookie Settings and Policy

Our use of Cookies

We use cookies that are essential for accessing our websites and using our services. We also use cookies to analyse, measure and improve our websites’ performance, to enable content sharing via social media and to display media content hosted on third-party platforms.

You can manage your cookie preferences and find out more by visiting 'Cookie Settings and Policy'.

ESO Cookies Policy


The European Organisation for Astronomical Research in the Southern Hemisphere (ESO) is the pre-eminent intergovernmental science and technology organisation in astronomy. It carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities for astronomy.

This Cookies Policy is intended to provide clarity by outlining the cookies used on the ESO public websites, their functions, the options you have for controlling them, and the ways you can contact us for additional details.

What are cookies?

Cookies are small pieces of data stored on your device by websites you visit. They serve various purposes, such as remembering login credentials and preferences and enhance your browsing experience.

Categories of cookies we use

Essential cookies (always active): These cookies are strictly necessary for the proper functioning of our website. Without these cookies, the website cannot operate correctly, and certain services, such as logging in or accessing secure areas, may not be available; because they are essential for the website’s operation, they cannot be disabled.

Cookie ID/Name
Description/Purpose
Provider (1st party or 3rd party)
Browser session cookie or Stored cookie?
Duration
csrftoken
XSRF protection token. We use this cookie to protect against cross-site request forgery attacks.
1st party
Stored
1 year
user_privacy
Your privacy choices. We use this cookie to save your privacy preferences.
1st party
Stored
6 months
_grecaptcha
We use reCAPTCHA to protect our forms against spam and abuse. reCAPTCHA sets a necessary cookie when executed for the purpose of providing its risk analysis. We use www.recaptcha.net instead of www.google.com in order to avoid unnecessary cookies from Google.
3rd party
Stored
6 months

Functional Cookies: These cookies enhance your browsing experience by enabling additional features and personalization, such as remembering your preferences and settings. While not strictly necessary for the website to function, they improve usability and convenience; these cookies are only placed if you provide your consent.

Cookie ID/Name
Description/Purpose
Provider (1st party or 3rd party)
Browser session cookie or Stored cookie?
Duration
Settings
preferred_language
Language settings. We use this cookie to remember your preferred language settings.
1st party
Stored
1 year
ON | OFF
sessionid
ESO Shop. We use this cookie to store your session information on the ESO Shop. This is just an identifier which is used on the server in order to allow you to purchase items in our shop.
1st party
Stored
2 weeks
ON | OFF

Analytics cookies: These cookies collect information about how visitors interact with our website, such as which pages are visited most often and how users navigate the site. This data helps us improve website performance, optimize content, and enhance the user experience; these cookies are only placed if you provide your consent. We use the following analytics cookies.

Matomo Cookies:

This website uses Matomo (formerly Piwik), an open source software which enables the statistical analysis of website visits. Matomo uses cookies (text files) which are saved on your computer and which allow us to analyze how you use our website. The website user information generated by the cookies will only be saved on the servers of our IT Department. We use this information to analyze www.eso.org visits and to prepare reports on website activities. These data will not be disclosed to third parties.

On behalf of ESO, Matomo will use this information for the purpose of evaluating your use of the website, compiling reports on website activity and providing other services relating to website activity and internet usage.

ON | OFF

Matomo cookies settings:

Cookie ID/Name
Description/Purpose
Provider (1st party or 3rd party)
Browser session cookie or Stored cookie?
Duration
Settings
_pk_id
Stores a unique visitor ID.
1st party
Stored
13 months
_pk_ses
Session cookie temporarily stores data for the visit.
1st party
Stored
30 minutes
_pk_ref
Stores attribution information (the referrer that brought the visitor to the website).
1st party
Stored
6 months
_pk_testcookie
Temporary cookie to check if a visitor’s browser supports cookies (set in Internet Explorer only).
1st party
Stored
Temporary cookie that expires almost immediately after being set.

Additional Third-party cookies on ESO websites: some of our pages display content from external providers, e.g. YouTube.

Such third-party services are outside of ESO control and may, at any time, change their terms of service, use of cookies, etc.

YouTube: Some videos on the ESO website are embedded from ESO’s official YouTube channel. We have enabled YouTube’s privacy-enhanced mode, meaning that no cookies are set unless the user actively clicks on the video to play it. Additionally, in this mode, YouTube does not store any personally identifiable cookie data for embedded video playbacks. For more details, please refer to YouTube’s embedding videos information page.

Cookies can also be classified based on the following elements.

Regarding the domain, there are:

As for their duration, cookies can be:

How to manage cookies

Cookie settings: You can modify your cookie choices for the ESO webpages at any time by clicking on the link Cookie settings at the bottom of any page.

In your browser: If you wish to delete cookies or instruct your browser to delete or block cookies by default, please visit the help pages of your browser:

Please be aware that if you delete or decline cookies, certain functionalities of our website may be not be available and your browsing experience may be affected.

You can set most browsers to prevent any cookies being placed on your device, but you may then have to manually adjust some preferences every time you visit a site/page. And some services and functionalities may not work properly at all (e.g. profile logging-in, shop check out).

Updates to the ESO Cookies Policy

The ESO Cookies Policy may be subject to future updates, which will be made available on this page.

Additional information

For any queries related to cookies, please contact: pdprATesoDOTorg.

As ESO public webpages are managed by our Department of Communication, your questions will be dealt with the support of the said Department.