Astronomers have, for the first time, detected a planet growing inside a cleared gap of a protoplanetary disk, confirming long-held theories about how young planets shape their star systems.

(An exoplanet is a planet outside our solar system.) GPI was installed on the 8-meter Gemini South Telescope in Chile in 2013, and its science operation began in 2014.

Astronomers have discovered a brand new type of planet outside our solar system that, even in its infancy, is already bigger ...

Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

Astronomers have discovered the earliest seeds of rocky planets forming in the gas around a baby sun-like star, providing a precious peek into the dawn of our own solar system.

Are there any planets outside of our solar system? - Eli W., age 8, Baton Rouge, Louisiana This is a question that human beings have wondered about for thousands of years.

Astronomers have discovered the earliest seeds of rocky planets forming in the gas around a baby sun-like star, providing a precious peek into the dawn of our own solar system.

Since the first planet was discovered outside our solar system in 1992, astronomers have found the vast majority of the 160-plus planets so far with a technique called radial velocity.