Thu. May 19th, 2022

“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 might assume that astronomers do not think much about their own planet. If you ask an astronomer what their favorite planet is, you will definitely get a few fun facts about Jupiter, Saturn, Venus and maybe even Pluto or a random exoplanet. After all, we spend millions of dollars on telescopes and instruments that have to look as far away from 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 Earth’s orbit.

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 near as habitable as Earth. The space is truly anticipatory; scientists have shown how difficult it is to form complex molecules, let alone a planet teeming with life like Earth! Even if we looked at our neighbor, Mars, it would take a monumental amount of time and resources to terraform its surface. The earth is our home. And there is no Planet B.

A group of astronomers have 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 must both reduce their climate footprint and act as ambassadors for global change.

An equatangular projection of the earth with political boundaries marked.  Each country is colored between white, yellow, green, light 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 on planet Earth was to write an open letter to the astronomical community. This open letter is short and sweet (please read it word for word here). It calls for three actions that all astronomical institutions can solve:

  1. Mention sustainability as a primary goal,
  2. Introduce specific sustainable practices to reduce CO2 emissions,
  3. Communicate these changes clearly to both the members of the department and the 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 get a lot of answers depending on who you ask. However, it is not uncommon to hear that sustainability is an institution’s primary goal. Astronomers for Planet Earth calls for sustainability to be a priority for astronomical institutions. Sustainability should be a top priority for department heads and everyone else in a leadership position. The first step in dealing with the climate crisis is to recognize 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 in which astronomers make a significant contribution to carbon emissions: travel by plane, telescopic operation, and energy consumption from supercomputers, general purpose computers and general operating costs. Each of these columns is discussed in great detail in Nature papers written by A4E members. (We will also write astrobite summaries of these papers if you can not bother to read them now :))

Perhaps the easiest of the three is to embark on travel. Almost all astronomers have now experienced a virtual conference during the current global pandemic. By comparing carbon emissions from a conference, a member of the Astronomers for Planet Earth calculated that the personal European Astronomical Society annual conference produced over 3,000 times more CO2 than its virtual counterpart. In addition to the massive drop in carbon emissions, the virtual conference had more attendees and cost much less. Virtual conferences are also more accessible. Astronomers for Planet Earth encourage conference planners to consider virtual conferences in the future or at least offer a virtual component so attendees can make their own decisions.

Astronomers as climate crisis communicators

And finally, the letter calls for astronomers, along with climate scientists, to step up the speed of the current climate crisis. Before I go any further, let’s get straight: Astronomers are not climate scientists. We are not experts in climate change. Do not let an overconfident astronomer make you believe otherwise. However, astronomers have some relation to the public. Members of the public who come up with a bias against climate scientists may have a little more confidence in astronomers, as we are not directly connected to the science of climate change. We can share our unique perspective on the habitability of Mars and the extra incredible distances from exoplanets. Astronomers working on atmospheres on exoplanets or planets in our solar system are fully capable of talking about how unique our atmosphere is and how man-made runaway capitalism is the cause of the dramatic rise in greenhouse gases. We have the power as an astronomical society to lead the fight against the climate crisis.

To the left a fuzzy image, mostly black, with a stripe of red down the middle and a small green-blue dot in the middle.  To the right is blue text that says
To the left we have a picture of the Earth from the perspective of the Voyager 1 probe 40.5 au away, or 3.7 billion miles. The light blue dot is the Earth and inspired the famous quote by astronomer Carl Sagan. Photo credit: A4E press event, EAS general meeting, 1 July 2021

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

And even sign up astronomers for planet earth:

Keep an eye out for more coverage of the work this amazing organization is doing, 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 fourth 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 have been using high-resolution ALMA data to extract the 2D thermal structure of different types of disks using thermochemical modeling. Outside of astronomy, I love to belt showtunes, eat Thai food, I enjoy cooking, and I love to travel and explore new places. Check out my website:

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