Earlier this year participants in the Planet Hunters citizen science project

confirmed with 99.9 percent confidence the discovery of a Jupiter-sized planet called PH2b orbiting within the “habitable zone” of its star, the range where earth-like planets could have liquid water and possibly sustain life. The researchers also announced 42 new planet candidates, including 20 located in the habitable zone of their respective stars.

– Planet Hunters Project Confirms a New Planet in the “Habitable Zone” – Yale Scientific Magazine.

Participants in the project examine data from the Kepler space observatory, which monitors the light from over 100,000 stars simultaneously to look for dimming when a planet passes in front of the star as seen from earth.

Planets transiting across the face of a star will dim its light output.

While the Kepler group have software to find such dimming from the planet transits across the face of stars, there are significant advantages of humans examining the light data directly

Citizen scientists working on Planet Hunters, on the other hand, can consider transits on a case-by-case basis, and can visually detect planets which produce fewer dips in the light-curve; these are the planets with a wider orbit and a longer orbital period that Kepler algorithms often overlook. Nine of the recent planet candidates have orbital periods over 400 days, and most have periods longer than 100 days.

“I didn’t expect that volunteers would be able to find a significant number of planets that the Kepler computers couldn’t. Everything found by volunteers causes Kepler to improve their algorithms,” Professor Fischer added.

Examples of a Kepler data for a planetary transit: