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<\/p>\nNASA has announced the discovery of a planetary system around star K2-138. The discovery was the first of its kind, being made by citizen scientists using data from the K2 mission as part of the Zooniverse Exoplanet Explorers effort. This detection is the first multi-planet system discovered exclusively by crowdsourcing \u2013 the practice of obtaining services and\/or content by soliciting contributions from a large group of people, especially from the public, online community.\n<\/p>\n
Exoplanet discovery background:<\/b><\/p>\n
The age of exoplanet discovery, as part of humanity\u2019s ongoing effort to map the universe and understand its workings, began in 1989 with the detection of what is now known to be the actual first exoplanet discovery, Gamma Cephei Ab.<\/p>\n
Due to the burgeoning nature of exoplanet research in 1989, doubt was originally cast on this exoplanet\u2019s existence (and its \u201cdiscovery\u201d was even retracted for a time), which was discovered via radial velocity \u2013 measuring observed Doppler shifts in the spectrum of an exoplanet\u2019s parent star. However, subsequent study of Gamma Cephei A finally led to the exoplanet\u2019s official confirmation in 2002.<\/p>\n
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Artist\u2019s impression of Gamma Cephei Ab, the first exoplanet to be discovered. Credit: NASA<\/p>\n
From the time of the first exoplanet discovery until 2010, a relative handful of exoplanets were found \u2013 including the least massive planet ever discovered (just twice the mass of Earth\u2019s moon) \u2013 in various star systems, with a majority of those planets being gas giants. But the discoveries were relatively few and far between and were largely complicated by Earth\u2019s atmosphere and rotation that prevented sustained, continuous observations of stellar systems.<\/p>\n
The answer to this problem was the space-based Kepler observatory. Launched in 2009, Kepler\u2019s mission was, in simple terms, to find Earth-sized planets orbiting other stars and determine how common Earth-sized planets are. In so doing, it was known that Kepler would find numerous other planets much larger than Earth and would greatly increase our knowledge of extrasolar system composition and exoplanet frequency.<\/p>\n
Kepler was a quantum leap forward in exoplanet discovery, detecting thousands of \u201cKepler objects of interest\u201d (planet candidates) by staring exclusively for four years at a region of the sky in the constellations Cygnus and Lyra and transmitting the light curve data of every star in its field of view to professional scientists on Earth.<\/p>\n<\/p>\n