Astronomy Picture of the Day

Explanation: Do other stars have planets like our Sun? Surely they do, and evidence includes slight star wobbles created by the gravity of orbiting exoplanets and slight star dimmings caused by orbiting planets moving in front. In all, there have now been over 5,500 exoplanets discovered, including thousands by NASA's space-based Kepler and TESS missions, and over 100 by ESO's ground-based HARPS instrument. Featured here is an illustrated guess as to what some of these exoplanets might look like. Neptune-type planets occupy the middle and are coloured blue because of blue-scattering atmospheric methane they might contain. On the sides of the illustration, Jupiter-type planets are shown, coloured tan and red from the scatterings of atmospheric gases that likely include small amounts of carbon. Interspersed are many Earth-type rocky planets of many colours. As more exoplanets are discovered and investigated, humanity is developing a better understanding of how common Earth-like planets are, and how common life might be in the universe.