Mercury is the smallest planet in our solar system. Explore its size, extreme temperatures, core structure, and comparison with Pluto.

Astronomers believe they have uncovered evidence of a previously unknown ninth planet lurking in the not-too-distant reaches of the solar system. This hypothetical world, dubbed "Planet Y," could be ...

New research using NASA’s James Webb Space Telescope examines the maximum sizes of gas giant exoplanets, measuring chemical compositions and formation processes in the HR 8799 system.

A newly discovered warp in the outer Solar System may have been created by a small, rocky world, much closer to the Sun than the hypothesized Planet Nine. According to a new measurement of the Kuiper ...

The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have dubbed ...

Jupiter is the largest planet in our Solar System and the fifth planet from the Sun. It is a massive gas giant made mostly of hydrogen and helium, the same elements that form stars.

A newly studied solar system breaks the usual planet pattern, raising fresh questions about how rocky and gas planets form.

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth than the hypothetical Planet X, which astronomers have been hunting for ...