We at Planet Hunters are thrilled to be part of this year’s BBC Stargazing Live – three nights of astronomy programing featured on the BBC hosted by Dara O Briain and Prof Brian Cox. Existing Planet Hunters will be glad to know that to celebrate we’ve put brand new data up on the site – Quarter 4 has now been added and there’s more to come. We’re keen to win the race to find whatever’s in this dataset, and so we’ve challenged the viewers of Stargazing to help us view 250,000 classifications light curves in the next 2 days.There’s a countdown on the Planet Hunters homepage, and we’ll announce what we might have found on Wednesday’s edition of Stargazing.
If you’re new to PH, let us tell you more about the project. With your help, we are looking for planets around other stars. When an extrasolar planet or exoplanet passes in front of its parent star, or transits, a dimming of the star’s light is observed. The transit depth, or decrease in the star’s brightness, is related to ratio of the planet’s radius to that of the star. For a Jupiter-‐ sized planet (~10 Earth radii), the transit depth is ~1% of the star’s apparent brightness. For Earth-‐sized planets, the drop in brightness is less than 0.01%.
NASA’s Kepler spacecraft monitors ~150,000 stars for transit signatures taking a measurement every 30 minutes.The Kepler light curves, the time series of brightness measurements, are complex. Many exhibit short-‐lived variations in brightness. Such variability is difficult to characterize. Using computer algorithms, the Kepler team has detected over 2,000 potential planet candidates and 33 confirmed planetary systems. Despite the impressive success of the Kepler Team’s automated analysis, we think that computers may not recognize transit signals dominated by the natural variability of the star.
Computers are only good at finding what they’ve been told to look for. The human eye can easily identify deviant points and transits that may be missed by sophisticated computer algorithms. The human brain has the uncanny ability to recognize patterns and immediately pick out what is strange or unique, far beyond what we can teach machines to do. With Planet Hunters we asking you to visually screen the Kepler light curves for transits, individually reviewing 30-day segments of a star’s light curve for tell-tale transit dips signaling the possible presence of a exoplanet. Over 73,000 volunteers have made nearly 6 million classifications in the project’s first year. We’ve already netted 4 strong planet candidates (read more about those discoveries here and here) that were missed in initial reviews in other searches of the Kepler data.
These Kepler observations have never before been seen by anyone on the Planet Hunters website. Most of the light curves will be flat devoid of transit signals but yet,it’s just possible that you might be the first to know that a star somewhere out there in the Milky Way has a companion, just as our Sun does. Fancy giving it a try?
~Meg, Chris and the Planet Hunters Team
PS. For comments for Stargazing Live – come to our Live Blog Post