CalTech scientist Mike Brown’s research debunked Pluto’s original claim to planetary existence, which he detailed in his 2010 book, How I Killed Pluto and Why It Had It Coming. He explained in a 2011 interview with EarthSky, “What led to the demotion of Pluto was the realization that Pluto is not this unique object in the solar system, in the way that the eight planets are. It’s really part of this whole field of debris.” In January 2016, Brown and his colleague Konstantin Batygin found evidence for a potential replacement for Pluto as the true ninth planet in our solar system. Through mathematical models, Brown and Batygin deduced that a planet 5,000 times the size of Pluto is exerting gravitational influence on the solar system. The planet nine theory was originally cited in 2014 as a possible explanation for six dwarf planets outside the Kuiper belt appearing to be influenced by a large planet in the region, and Brown’s research corroborated this theory. The only problem is the difficulty of finding the ninth planet.
Earth’s outer solar system is largely unexplored given the lack of sunlight in the vast region. The technology capable of scanning this territory has only recently become available. The end of the solar system is three times further than Pluto, making the process of finding the ninth planet a daunting task. To assist in this search, scientists from around the country have developed an online citizen science project, Backyard Worlds: Planet 9, for people to scroll through images taken by NASA’s Wide-field Infrared Survey Explorer satellite. “So far, we know of eight planets orbiting the Sun, but there could be more out there to find,” states the project’s website. “Patterns in the orbits of the comet-like objects in the outer solar system (the Kuiper belt) suggest that there is a ninth planet orbiting beyond Neptune. Models of this planet imply that we may have already imaged it with NASA’s WISE telescope and simply not recognized it. Together, we’re going to look through the data from this telescope in a powerful new way to try to spot it.”
They explain why human eyes, rather than computers, are required to scan through these images: “While it’s possible to process the data to find moving points of light, we can’t get rid of all the noise. Spiky images of stars, especially variable stars, are everywhere. Worse are the optical ghosts, blurry blobs of light that have been scattered around inside WISE’s instruments. These can hop back and forth or even change color. These artifacts can easily fool our image processing software. But with your powerful human eyes, you can help us recognize real objects of interest that move among these artifacts. You’ll be able to tell what objects are real by the way they move around differently from the artifacts.” The project cites citizen astronomers may also discover dwarf planets, failed stars, or other celestial objects that have yet to be identified.
The process can take hours, as images must be scanned in section to decipher true detections of a celestial object from blurry spots on the images. Once an object of interest is marked, the astronomers leading the project take over, which include Jackie Faherty of the American Natural History Museum and principal investigator Marc Kuchner of NASA’s Goddard Space Flight Center. If the object of interest is verified by scientists, they will follow up with telescope observations. So far, five possible failed stars have been verified through the project and the first brown dwarf star discovered by the project was published on May 8 in Astrophysical Journal Letters. The elusive planet nine discovery is possibly on the horizon.