Citizen scientists join the search for Planet 9

Astronomers want you in on the search for the solar system’s ninth planet.

In the online citizen science project Backyard Worlds: Planet 9, space lovers can flip through space images and search for this potential planet as well as other far-off worlds awaiting discovery.

The images, taken by NASA’s Wide-field Infrared Survey Explorer satellite, offer a peek at a vast region of uncharted territory at the far fringes of the solar system and beyond. One area of interest is a ring of icy rocks past Neptune, known as the Kuiper belt. Possible alignments among the orbits of six objects out there hint that a ninth planet exerting its gravitational influence lurks in the darkness (SN: 7/23/16, p. 9). The WISE satellite may have imaged this distant world, and astronomers just haven’t identified it yet. Dwarf planets, free-floating worlds with no solar system to call home (SN: 4/4/15, p. 22) and failed stars may also be hidden in the images.
The WISE satellite has snapped the entire sky several times, resulting in millions of images. With so many snapshots to sift through, researchers need extra eyes. At the Backyard Worlds website, success in spotting a new world requires sharp sight. You have to stare at what seems like thousands of fuzzy dots in a series of four false-color infrared images taken months to years apart and identify faint blobs that appear to move. Spot that movement and you may have found a new world.

But you can’t let blurry spots or objects moving in only a couple of the frames fool you: Image artifacts can look like convincing space objects. True detections come from slight shifts in the positions of red or whitish-blue dots. With so many dots to track, it’s best to break up an image into sections and then click through the four images section by section. This process can take hours. But think of the payoff — discovering a distant world no one has observed before.

Once you’ve marked any potential object of interest, the project’s astronomers take over. Jackie Faherty of the American Museum of Natural History in New York City and colleagues cross-reference the object’s coordinates with databases of celestial worlds. If the object does, in fact, appear to be a newbie, the team requests time on other telescopes to do follow-up. Those studies can reveal whether the object is a failed star or a planet.

So far, tens of thousands of citizen scientists have scoured images at Backyard Worlds. The team has identified five possible failed stars and had its first paper accepted for publication.

But there’s still much more to explore: The elusive Planet Nine might still be out there, disguised as a flash of dots.