Citizen Science: Astronomy Edition

Thanks to large scale surveys of the sky, astronomers have more data than they can possibly look at on their own and they are looking for help from citizen scientists. Find out how you could be the first to classify a new galaxy or find the 9th planet in our solar system.

Sabrina Stierwalt, PhD
4-minute read
Episode #227

When you visit the Galaxy Zoo webpage, emblazoned across the top is the phrase “Few have witnessed what you’re about to see.” This is, of course, true. Galaxy Zoo asks citizen scientists to look at images of galaxies taken as part of surveys so large that there are not enough astronomers in the world to look at each and every one.

Astronomers have designed algorithms that are able to automate the process of source detection in surveys, but only to a certain point. So far, nothing can beat the pairing of the human eye and our deductive reasoning skills to do more nuanced tasks like classifying galaxies into categories. When Galaxy Zoo was first launched in 2007, participants were only asked a few, very simple questions about the shape of each object, i.e. is the galaxy round, disk-like, or irregular? However, the project’s creators soon realized that citizen scientists were capable of providing consistent answers to much more complicated questions. Now  participants are asked more detailed questions like, “Is the object smooth or clumpy?” “How many spiral arms does it have?” or “Does the galaxy appear to have a bar in the middle?”

The classification of such a large number of galaxies is crucial to our understanding of how galaxies, including our own Milky Way, form. Since most processes in galaxy evolution happen on very long time scales (we’re talking hundreds of millions of years), astronomers don’t get to watch most of these events occur. Instead, we observe many different galaxies which serve as snapshots at different points in galaxy evolution. Astronomers then have to put these snapshots together in the order they might occur to understand how galaxies form and evolve.

An Earth-bound analogy would be if you were handed a family photo album and asked to piece the photos together in sequential order for the different people in the album. Some aspects of the task might be more straight forward: this teenager clearly looks like a bigger version of this small child, so I’m going to guess the small child came first and grew into the young adult. But will I ever evolve into my sister? We look a lot a like but what if something in my history sends me on a very different evolutionary path? And what about my cousin? We may have started with very similar conditions but we grew up in different environments.

One of the trickiest questions for astronomers can be whether, when looking at two different galaxies, they represent two different evolutionary stages in the life of one type of galaxy, or they are two entirely different kinds of galaxies on separate evolutionary paths. Answering these kinds of questions is not possible without amassing information on many, many different galaxies caught in different stages of their evolution.

The Galaxy Zoo framework is set up so that many different participants view each galaxy in order to discard any outlier answers. This, by the way, is how almost all of science is done, citizen or otherwise—many measurements are made and the average best represents the answer.

The Galaxy Zoo project is also continually adding new datasets (and retiring images that have been fully investigated) so that your experience as a Citizen Scientist is unique each time you visit and you really can be the first to view the latest galaxy additions. Current datasets include those of the Sloan Digital Sky Survey, a deep multi-color survey of one third of the sky, the Hubble Space Telescope’s CANDELS Survey which probes even deeper into the more distant universe thanks to Hubble’s sensitivity, and the UKIDSS project which provides the deepest infrared look at the sky thanks to the UKIRT telescope in Hawaii. Galaxy Zoo also recently added images from the Dark Energy Camera Legacy Survey which uses the extremely sensitive DECam to understand dark energy.

The Galaxy Zoo project has resulted in the largest number of publications of any online citizen science project. But if perusing scientific publications isn’t your thing, there is also a blog where the authors break down the highlights of some of their recent results. You can also read more about galaxy formation and evolution, as well as the history of the Galaxy Zoo program itself, on the site.

Other astronomy-themed citizen scientist projects include Radio Galaxy Zoo which asks citizen scientists to search for black holes and Backyard Worlds where citizen scientists can search for movement in infrared survey images taken at different times to help in the search for Planet 9, a predicted but so far undetected planet in our solar system. NASA’s JunoCam also allows participants to choose where the camera onboard the Juno spacecraft will take its next images of Jupiter and to process their own Jupiter images.

The success of Galaxy Zoo has also inspired the Zooniverse project, a framework that hosts similar citizen scientist projects across a broad range of science topics. Citizen scientists using Galaxy Zoo cited contributing to scientific research as their main motivation for participating in the project. So if you’re in the mood for a little science, whether you have ten minutes or hours to share, there are many projects that need your help. Contributors spanned ages of 20 to 60 fairly evenly, but less than 20% of respondents to the survey were women. So while you’re at it, get your daughter, niece, or sister involved too.

Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

Image courtesy of nasa.gov

Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.

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