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Planetary science

Planetary science

Web life: Backyard Worlds: Planet 9

27 Apr 2017
Taken from the April 2017 issue of Physics World

So what is the site about?

Much as its name suggests, Backyard Worlds: Planet 9 focuses on the hunt for a ninth planet in our solar system, along with other possible “rogue” planets that astronomers now believe may abound in the galaxy. The idea is to look though data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission and distinguish certain features – following in the vein of a number of other celestial citizen-science projects. The data in this case are in the form of animated images of the sky, taken at different times. As a participant, your job is to pick out moving celestial bodies – mainly ultracool brown dwarfs and other rogue planets – from artefacts in the data. As the site suggests “There are too many images for us to search through by ourselves. So come join the search, and you might find a rogue world that’s nearer to the Sun than Proxima Centauri – or even the elusive Planet Nine.”

Who is behind it?

It should come as no surprise that Backyard Worlds is part of the Zooniverse family. In case you haven’t come across it before, Zooniverse claims to be the “world’s largest and most popular platform for people-powered research”. Its science programmes involve everything from spotting distant galaxies to counting animals in the wild. The idea is to tap into people’s interest in science, whether or not they have a science degree and use their help to pick out details in large data-sets – a task that computers are still much slower at than the average person.

The Backyard Worlds team is made up of researchers from the American Museum of Natural History, the Space Telescope Science Institute, NASA, the University of California, Berkeley and Arizona State University.

Can I get involved?

Yes of course – that is the aim of the game. At the time of writing, the site had 26,383 registered volunteers who had completed 2,314,451 classifications, but that isn’t even halfway to the goal so there is plenty more help you can offer. Your main task as a volunteer is to look through sets of false-colour images, taken at four different times. You use a marking tool to point out artefacts that are moving through these images, either hopping and jumping across the set of images (“mover”) or appearing as pairs of varying bright and dark spots (a “dipole”). If you think you have spotted a possible dipole or mover, you report it via the chat function by providing the object’s celestial coordinates (simply called Talk, this section also allows you to chat with other users as well as the scientists involved, making it a great open discussion platform).

The next step is to cross-reference your discovery against a database of known astronomical objects. Dubbed the “Set of Identifications, Measurements, and Bibliography for Astronomical Data” or SIMBAD, this database is used by professional astronomers. If your coordinates do not align with an existing object, you get to fill out an exciting “Think you’ve got one?” form with details of your find. At this point, the professionals take over as they first research the object to see what we already know about it, before following up with observations of the most promising candidates. “We need to apply for telescope time to follow up the most interesting objects to take their spectra,” explains the site, adding that “The spectra will allow us to figure out their spectral types and their temperatures, and find out if what we’re looking at really is a new brown dwarf or planet. That whole process will take several months.”

Who is it aimed at?

To some extent, the site is aimed at anyone who would like to hunt for new planets. But Backyard Worlds needs a bit more time and attention than some of the other Zooniverse projects. While looking through the data and marking artefacts is simple, some users may be thrown by having to determine the celestial coordinates and then use the somewhat complicated SIMBAD database to find more data on their discoveries. That said, there are detailed “how to” guides and blog posts on each of these topics and the Talk feature allows you to ask for help if you need it. Ultimately, the hard work will pay off for all volunteers as everyone will be credited with any potential discoveries. And really, how many people can say they helped to find a planet?

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