This artist concept shows K2-138, the first multi-planet system discovered by citizen scientists. The central star is slightly smaller and cooler than our Sun. The five known planets are all between the size of Earth and Neptune. Planet b may potentially be rocky, but planets c, d, e, and f likely contain large amounts of ice and gas. All five planets have orbital periods shorter than 13 days and are all incredibly hot, ranging from 800 to 1,800 degrees Fahrenheit. https://photojournal.jpl.nasa.gov/catalog/PIA22088

This artist's illustration shows the planetary system K2-138, which was discovered by citizen scientists in 2017 using data from NASA's Kepler space telescope. Five planets were initially detected in the system. In 2018, scientists using NASA's Spitzer Space Telescope found evidence of a sixth planet in the system. https://photojournal.jpl.nasa.gov/catalog/PIA23002

This image shows the estimated radii of the six planets in the planetary system K2-128, as well as their distance from the parent star. The radii of the Earth and Neptune are shown for scale. https://photojournal.jpl.nasa.gov/catalog/PIA23003