The mysterious Kepler-1625b-i and its parent planet may once have been siblings. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. The first ...

Astronomers have unexpectedly discovered the heaviest Neptune-like planet yet — one more than four times the mass of our solar system's Neptune — yet it remains a mystery how the world might have ...

Add Yahoo as a preferred source to see more of our stories on Google. An artist's illustration of a hot, Neptune-size alien planet. Warm Neptune-size exoplanets are not nearly as common as ...

A team working with data from the dearly departed Kepler space telescope has reported a possible moon orbiting an exoplanet some 5,000 light years away. It falls somewhere between the size of Earth ...

Water vapor has been detected in the atmosphere of a Neptune-size exoplanet about 150 light-years from Earth, according to research presented Thursday by astronomers at the University of Kansas.