Astronomers discovered the stars closest to our Solar System more than 100 years ago. There’s the three-star Alpha Centauri system about four light-years away and Barnard’s star about six light-years out.
But our celestial neck of the woods might be more crowded than we ever thought possible. In the past 25 years, astronomers have been identifying new objects that are also just a few light-years away: mysterious worlds known as brown dwarfs. Too large to be a planet but too small to become a star, brown dwarfs put out very little visible light, yet they glow brightly in the infrared. New infrared-enabled telescopes can image brown dwarfs effectively and have led to a raft of new discoveries — including a pair of dwarfs just past Barnard’s star. This pair is now the third-closest known system to ours.
There are untold thousands of unidentified brown dwarfs hiding in telescope imagery right now, but they aren’t exactly easy to pick up: they register as tiny smudges against a sea of other stars, galaxies, and photographic aberrations. It takes a careful human eye to spot them, so researchers interested in brown dwarf discovery find themselves in a bind: how to manually sift through millions of images of the night sky?
A few years back, a group of astronomers came up with a clever solution to that problem: a worldwide citizen-science effort that allows anyone with an internet connection to search through telescope imagery for new worlds. The project leverages an age-old trick to tease movement out of celestial imagery, and it’s allowed volunteers to locate thousands of new brown dwarfs. The effort may unearth worlds even closer to our Solar System than Alpha Centauri and could even turn up the Bigfoot of our Solar System: a hypothesized Planet 9.
Check out the video above to see how world-hunting works, and try it out for yourself on the project website.