Citizen scientists have spearheaded the discovery of 95 new brown dwarfs, most of them exceptionally cold and located just tens of light-years from our Sun.
In 2018, NASA launched Backyard Worlds: Planet 9, a citizen science platform featuring hundreds of millions of infrared sky images from the WISE telescope. Participants can scan for moving objects from home.
The site provides flipbook animations of sky patches taken at different times, enabling users to spot gradual motion. Astronomers then verify promising candidates.
Originally aimed at finding the hypothetical Planet 9, the project has instead revealed hundreds of other solar neighborhood objects, including brown dwarfs. These failed stars are too massive for planets but too small for sustained hydrogen fusion, so they don't shine like true stars.
Citizen researchers using Backyard Worlds data have confirmed 95 brown dwarfs near the Sun. As Aaron Meisner of the National Science Foundation notes, "members of the public can play an important role in reshaping our scientific understanding of our solar neighborhood."
While some brown dwarfs reach thousands of degrees, these newcomers are much cooler—some nearing Earth's temperatures and potentially hosting water clouds.
NASA states: "Discovering and characterizing astronomical objects near the Sun is fundamental to understanding our place and the history of the universe." These cold brown dwarfs fill a missing link in the population.
Six years ago, the 23°C brown dwarf WISE 0855—still the coldest known—baffled astronomers amid hotter peers. NASA astrophysicist Marc Kuchner explains: "this new discovery helps us connect the dots between 0855 and other known brown dwarfs."
