A new study suggests yet another theory for a possible extra planet in our solar system, likely of a size between Mercury and ...

The bold question-askers at What If examine what life would be like if Earth were the only planet in the solar system.

On August 24, 2006, our solar system lost a planet. It wasn't by cataclysmic destruction, but rather by the vote of the International Astronomical Union, which declared that Pluto, considered the ...

The official number of planets outside our solar system has reached 6,000, according to space scientists. Get any of our free email newsletters — news headlines, sports, arts & entertainment, state ...

Astronomers have been fascinated after spotting an object earlier this year that came from interstellar space as is now hurtling through our inner solar system. Regardless, it’s an interesting visitor ...

A pioneering study by the Institute of Geological Sciences at the University of Bern has for the first time established a ...

Astronomers using the Hubble Space Telescope have observed a white dwarf - a highly compact stellar ember - that appears to ...

The third interstellar object ever detected in the solar system will make a close approach to Mars, giving the opportunity ...

Astronomers have uncovered a massive new trans-Neptunian object, 2017 OF201, lurking at the edge of our solar system. With an orbit stretching 25,000 years and a size that may qualify it as a dwarf ...

The official number of planets outside our solar system has reached 6,000, according to space scientists. NASA's tally of exoplanets does not include more than 8,000 additional candidate planets ...