On August 24, 2006, in Prague, members of the International Astronomical Union gathered for the final day of their General ...

The solar system lost its ninth planet back when Pluto was demoted to a dwarf planet, but research might indicate that there is a distant Planet Nine out there.

Twenty years after Pluto became a dwarf planet, people are still fighting over its status. Experts explain why the debate feels so personal.

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 ...

Why are there moons at the edge of the solar system that cause their rotation axes to fluctuate as if ignoring the laws of ...

Twenty years after Pluto lost its planetary status, the debate continues as scientists still disagree over what defines a planet.

For decades, scientists and the general public have argued over the astronomical status of beloved dwarf planet Pluto. In the latest salvo, NASA Administrator Jared Isaacman said that he was “very ...

Add Yahoo as a preferred source to see more of our stories on Google. Guests visting the Lowell Observatory in Flagstaff, Arizona during the I Heart Pluto Festival gaze at celestial objects from the ...

NASA Administrator Jared Isaacman wants to put an end to a decades-long debate among scientists. Is Pluto a planet or not? Isaacman says it should be — but it hasn't been one for 20 years. That's ...

Orbit diagram for the outer solar system. The Sun and Terrestrial planets are at the center. The Kuiper Belt (including Pluto) is shown by the dotted light blue region just beyond the giant planets.

Today, the dwarf planet Pluto orbits the sun from the edge of our solar system and its surface temperature is an inhospitable negative 378 to negative 396 degrees Fahrenheit. But a new study suggests ...