Because the financing for missions like Kepler is supported by tax dollars, it’s gratifying to see the public getting actively involved in working with actual data from the Kepler team. That’s what has been going on with the Planet Hunters site, where 40,000 users from a wide variety of countries and backgrounds have been analyzing what Kepler has found. Planet hunter Debra Fischer (Yale University), a key player in the launch of Planet Hunters, has this to say:

“It’s only right that this data has been pushed back into the public domain, not just as scientifically digested results but in a form where the public can actively participate in the hunt. The space program is a national treasure — a monument to America’s curiosity about the Universe. It is such an exciting time to be alive and to see these incredible discoveries being made.”

So far, so good on the citizen science front. Using publicly available Kepler data, Planet Hunters has found two new planets, both of them discarded initially by the Kepler team for a variety of technical reasons. Fischer believes the odds on the detections being actual planets are 95 percent or higher. The candidate planets have periods of 10 and 50 days, and radii from two and a half to eight times that of the Earth. One of them is conceivably a rocky world, though not in the habitable zone. Several dozen Planet Hunters users had spotted the planet candidates.

Image: One of the tutorial figures explaining how to use Planet Hunters at the site. The time it takes a planet to complete one orbit is called the orbital period. For transiting planets, this can be determined by counting the number of days from one transit to the next. Planets in longer period orbits will be more challenging to detect, both for humans and for computers because a transit will not appear in every 30-day set of light curve data. Large planets with short orbital periods are the easiest ones to detect. The most challenging detections will be small planets with long orbital periods. These will require patience and care, but are the real treasures in the Kepler data. Credit: Planet Hunters.

Following up the detection, astronomers used the Keck Observatory to study the host stars. A new study is to be published on the discoveries in the Monthly Notices of the Royal Astronomical Society, marking the first time the public has used NASA space mission data to find planets around other stars. So while the heavy lifting continues to be done by the Kepler team itself, public science has proven to be a helpful supplement, bringing more eyes to the data at hand. And, of course, the next round of Kepler data provides just as intriguing a hunting ground.

When it began, Planet Hunters was described as a bet on the ability of humans to beat computers, at least occasionally, because of the way people can use pattern recognition. The Kepler team uses computer algorithms fine-tuned to analyze light curve data because of the sheer number of stars the mission is working with. But while computers excel at finding what they are trained to find, the potential for surprise is always there as tens of thousands of users put pattern recognition to work to examine light curves, track down anomalies, and pay close attention to transit signals. For this kind of analysis, using powerful computers with a widely distributed human backup component is proving ideal for the task at hand.