Over the three-year mission, 287,309 stars were observed and tens of thousands more rolled in every few months.
They also discovered 44 Jupiter-sized planets, 72 Neptune-sized, 44 Earth-sized, and 53 so-called Super Earth’s, which are larger than Earth but smaller than Neptune.
But the most exciting discovery for some was the K2-138 planetary system, home to at least five “sub-Neptune” planets between the size of Earth and Neptune, nearly 620 light years from Earth.
The exoplanet family was discovered after researchers launched a crowdsourcing project to help sift through three years’ worth of data from 280,000 stars.
And findings from citizen scientists helped lead to the discovery, which is the first of its kind made through crowdsourcing.
Members of the public were given access to the project in an attempt to speed up the research after a software malfunction meant scientists would have to manually comb through the data, collected using the NASA Kepler space telescope.
K2 collaboration member at the California Institute of Technology (Caltech) Jessie Christensen said: “People anywhere can log on and learn what real signals from exoplanets look like, and then look through actual data collected from the Kepler telescope to vote on whether or not to classify a given signal as a transit or just noise.
“We have each potential transit signal looked at by a minimum of 10 people, and each needs a minimum of 90 percent of ‘yes’ votes to be considered for further characterisation.”
Within 48 hours of the citizen science project launch, more than 10,000 people had participated, with over two million systems classified.
After three nights, the K2-128 system was identified – which has been described as the “first multiplanet system of exoplanets discovered entirely by crowdsourcing”.
Astronomers reviewed the citizen scientist data and confirmed the existence of the new system, claiming it’s “extremely likely” it contains at least four planets and a possible fifth.
There have even been some hints at a sixth planet in the system, which orbits around star K2-138.
Dr Christiansen said: “Some current theories suggest that planets form by a chaotic scattering of rock and gas and other material in the early stages of the planetary system’s life.
“However, these theories are unlikely to result in such a closely packed, orderly system as K2-138.”
“What’s exciting is that we found this unusual system with the help of the general public
The findings have been published in the Astrophysical Journal and were presented at the meeting of the American Astronomical Society.