Discovered in 1930 at the Lowell Observatory, Pluto was demoted as a planet in 2006. Some want President Trump to take action ...

An Arizona observatory where Pluto was discovered turns a summer night into a dreamy mix of stargazing and history.

February 18 marks the discovery of Pluto by astronomer Clyde W. Tombaugh. The discovery reshaped the understanding of the solar system, as Pluto was long considered the ninth planet until the ...

Scientists have recently unveiled a remarkable discovery in the outer reaches of our solar system: a space fossil located 4 billion miles past Pluto, covered in unidentified organic molecules. This ...

Billions of years ago, in the frozen edges of the solar system, a violent impact shaped one of space's oddest pairs. Instead of a typical planet-moon setup, Pluto and Charon became a binary system.

Pluto, discovered 90 years ago on Feb. 18, 1930, was long considered the solar system's ninth planet. Although small, it orbits the sun and has the spherical shape required to be considered a planet.