"People anywhere can log on and learn what real signals from exoplanets look like, and then look through actual data collected from the Kepler telescope to vote on whether or not to classify a given signal as a transit, or just noise", said Christiansen in a Caltech news release.
For the first time ever, citizen scientists have successfully discovered a new planetary system, located outside our solar system, around 620 light years away within the Aquarius constellation. They are all being classified as super-Earths, weighing in at about two to three times larger than our planet. Eventually, more planets could be discovered orbiting the system's star.
The raw data used in the discovery was provided by Nasa's Kepler space telescope, which identifies potential planets around other stars by looking for dips in the brightness of those stars when planets pass across their face - or transit them.
At least 10 users would have to look at a potential signal, and 90 per cent of these users would have to vote "yes", for researchers to consider the signal for further analysis. The size of each planet's orbit appears to be a ratio of the other orbits, suggesting that all five planets originally formed together in a smooth, rotating disc, and over eons migrated closer in towards their star.
As citizens contributing to the Exoplanet Explorers shared, K2 had a whole new field of stars that might host planets, contained in a dataset called C12 that no astronomer had yet thought to look through.
"That's a really tantalising clue that we may be missing more planets in this system". And that is how the five exoplanets of K2-138 were found. They statistically validated the set of planet signals as being "extremely likely", according to Christiansen, to be signals from true planets. A fifth planet was also discovered on the same chain, with hints of a sixth as well. A paper describing the system has been accepted for publication in The Astronomical Journal. They also found that the planets are orbiting in an interesting mathematical relationship called a resonance, in which each planet takes nearly exactly 50 percent longer to orbit the star than the next planet further in.
"The clockwork-like orbital architecture of this planetary system is keenly reminiscent of the Galilean satellites of Jupiter", says Konstantin Batygin, assistant professor of planetary science and Van Nuys Page Scholar, who was not involved with the study, said in a statement. "However, these theories are unlikely to result in such a closely packed, orderly system as K2-138", said Dr Christiansen.
"What's exciting is that we found this unusual system with the help of the general public".
The project that allowed citizen scientists to make the discovery is called Exoplanet Explorers, and is part of the popular citizen scientist platform Zooniverse. Funding was provided by the NASA Science Mission Directorate, Google, the Alfred P. Sloan Foundation, NASA, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.