A group of citizen scientists helped astronomers discover an exoplanet that is nearly twice the size of Earth and may even be habitable—using data from NASA’s Kepler space telescope.
Called K2-288Bb, the planet, located 226 light years from the Sun, orbits its red dwarf star every 31.3 days, placing it within or near the habitable zone. That means it could potentially have liquid water on its surface, though this is speculative and based only on its distance from its star.
The newly identified world is about 1.9 times the size of Earth, meaning that it is likely a “Super-Earth” or a mostly gaseous orb. Its size is particularly tantalizing, according to NASA, because planets that are 1.5 to two times larger than Earth are rarely found in such close orbits around their stars.
Feinstein and her colleague Makennah Bristow have been chasing the exoplanet since 2017, when they observed two of its transits while interning at NASA’s Goddard Space Flight Center. Transits occur when planets pass in front of their stars from our perspective on Earth, causing a slight dip in stellar brightness.
Two transits are not enough to establish the pattern needed to detect an exoplanet. As it turned out, however, Kepler had spotted a third transit. That dataset had not been carefully examined because it was captured in 2014, when the Kepler team was getting accustomed to operating in its “K2” mode. Kepler was retired in October 2018, after running out of fuel.
This sidelined data was re-processed and posted to Exoplanet Explorers, a Zooniverse community of over 21,000 citizen scientists who help astronomers spot transits in Kepler data. In May 2017, Exoplanet Explorers flagged a potential transit in the K2-288 system, which contains two red dwarf stars. That ended up being the sought-after third detection of K2-288Bb.
Feinstein and her colleagues confirmed the existence of the exoplanet with follow-up studies using NASA's Spitzer Space Telescope and the Keck Observatory in Hawaii, among others.
This new find is one of many exoplanet detections made possible by the support of citizen scientists. As more data from next-generation telescopes becomes available, Feinstein’s team suggests greater investment in public volunteers, including regularly crediting them for their contributions.
“The role of citizen scientists will likely become even more crucial to the detection of interesting transiting exoplanets,” the authors wrote in the paper. “Through continued engagement with the public via outreach and social media, we aim to foster continued interest in exoplanet citizen science and continue to validate interesting planetary systems that may otherwise be missed by automated software searches.”
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