Introducing: Astronomers for Planet Earth

“We, astronomers, astrophysicists, and global citizens, recognize the urgency of the climate crisis and our impact on it. We also recognize that we have the power to change our current practices.” 

-Astronomers for Planet Earth

You may assume that astronomers don’t think much about their own planet. If you ask an astronomer what their favorite planet is, you’re sure to get an earful of fun facts about Jupiter, Saturn, Venus, and maybe even Pluto or some random exoplanet. After all, we spend millions of dollars on telescopes and instruments that are meant to look as far away from the Earth as possible. We find creative ways to look through and beyond our atmosphere, and even chuck some of our telescopes outside the atmosphere, into or beyond the orbit of the Earth.

However, this work gives astronomers a unique perspective on how special our planet is. As of mid-2021, we have observed over 4,800 exoplanets, none of which appear nearly as habitable as Earth. Space is really foreboding; researchers have shown how difficult it is to form complex molecules, let alone a planet teeming with life like the Earth! Even looking at our next-door neighbor, Mars, it would take a monumental amount of time and resources to terraform its surface. Earth is our home. And there is no Planet B.

A group of astronomers has taken this to heart and formed a group called Astronomers for Planet Earth (A4E). It is an international group of more than 1,100 astronomy educators, students, and scientists who all feel strongly about the climate crisis we are currently facing. They believe that astronomers need to both decrease their climate footprint and act as ambassadors for global change.

An equirectangular projection of the earth with political boundaries marked. Each country is colored in between white, yellow, green, pale blue, and a dark blue corresponding to the number of signatures in that country, with white corresponding to zero and dark blue corresponding to 500.
The number of people who have signed the open letter written by the organization Astronomers for Planet Earth. Image credit: Colin Hill, A4E

Dear Astronomy, be better.

One of the first efforts of Astronomers for Planet Earth was to write an open letter to the astronomy community. This open letter is short and sweet (feel free to read it word for word here). It calls for three actions that all astronomy institutions can address:

  1. Name sustainability as a primary goal,
  2. Put in place specific sustainable practices to lower carbon emissions,
  3. Clearly communicate these changes to both institute members and the general public

Sustainability in Astronomy

What is the goal of astronomy as a field? What is the goal of an astronomy department? What is the goal of a university or research institute?  These are big questions, and you’ll get many answers depending on who you ask. However, it’s not common to hear that sustainability is an institution’s primary goal. The Astronomers for planet Earth call for sustainability to be named a priority of astronomical institutions. Sustainability should be a top priority for department heads and anyone else in a leadership position. The first step to addressing the climate crisis is to acknowledge that we are part of the problem. And as astronomers, we have the power to be part of the solution.

Carbon Emissions in my Astronomy? It’s more likely than you think

Members of the Astronomers for Planet Earth group have identified three main areas that astronomers contribute significantly to carbon emissions: travel via airplanes, telescope operation, and energy consumption from supercomputers, general computing, and general operation costs. Each of these pillars are discussed in great detail in Nature papers written by A4E members. (We will also write astrobite summaries of these papers if you can’t be bothered to read them now :))

Perhaps the easiest of the three to address is travel. Nearly all astronomers have now experienced a virtual conference during the current global pandemic. Comparing the carbon emission from a conference, a member of Astronomers for Planet Earth calculated that the in-person European Astronomical Society Annual conference produced over 3,000 times the CO2 than its virtual counterpart. In addition to the massive decrease in carbon emissions, the virtual conference had more attendees and cost much less. Virtual conferences are also more accessible. Astronomers for Planet Earth urge conference planners to consider virtual conferences in the future, or at the very least offering a virtual component to allow attendees to make their own decisions.

Astronomers as Climate Crisis Communicators

And finally, the letter advocates for astronomers to join climate scientists in amplifying the urgency of the current climate crisis. Before I go further, let’s get this straight: Astronomers are not climate scientists. We are not experts in climate change. Don’t let any overconfident astronomer let you think otherwise. However, astronomers do have a certain rapport with the public. Members of the public who come in with a bias against climate scientists might possibly have a bit more confidence in astronomers since we are not directly associated with climate change science. We can share our unique perspective about the habitability of Mars and the additional incredible distances of exoplanets. Astronomers that work on atmospheres of exoplanets or planets in our solar system are fully capable of speaking on how unique our atmosphere is, and how human-driven runaway-capitalism is the cause of the dramatic increase in greenhouse gases. We have the power, as an astronomy community, to lead the fight against the climate crisis.

To the left, a fuzzy picture that is mostly black, with a strip of red down the center and a tiny green-blue dot in the center. To the right there is blue text that says “Astronomers have.. A unique perspective, scientific expertise, and role as educators” and below the text is an image of an astronaut looking down onto the blue ocean of earth from outer space.
To the left we have a picture of the Earth from the perspective of the Voyager 1 probe at 40.5 au away, or 3.7 billion miles. The pale blue dot is the Earth, and inspired the famous quote by astronomer Carl Sagan. Image credit: A4E press event, EAS general meeting, July 1 2021

If these calls to action speak to you, feel free to sign the open letter:  

And even join astronomers for planet earth:

Look out for more coverage of the work this fantastic organization does, and more advice for us as individuals and as organizations in the coming months!

Astrobite edited by Pratik Gandhi, Mia de los Reyes, Suchitra Narayanan and is part of the Climate Change Series
Image Credit: Voyager 1, NASA

About Jenny Calahan

Hi! I am a forth year graduate student at the University of Michigan. I study protoplanetary disks, which set the stage for planet formation. For the past few years I've been using high resolution ALMA data to pull out the 2D thermal structure of different types of disks using thermo-chemical modeling. Outside of astronomy, I love belting showtunes, eating Thai food, I enjoy crafting, and I love to travel and explore new places. Check out my website:

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  1. Thank you for that important summary of A4E! I hope that astronomers will step up, calculate their GHG emissions, and then take action to reduce the use of fossil fuels in their research.

  2. Nice post!
    The link for the open letter does not work as there are some characters added (%C2%A0%C2%A0 on Safari at least)…


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