Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

Stars that pass close to the solar system could pull planets out of alignment, sending them hurtling into the sun or out into ...

This week, an old astronomical controversy is renewed as researchers present new evidence for a hidden "Planet X" in our ...

Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner ...

Earth has four seasons, but do other planets in our solar system also have hot summer days and cold winter nights?

Pluto, which infamously lost its status as the ninth planet in 2006, is less than four billion miles away from the sun, sitting in the Kuiper Belt - a region in our solar system beyond Neptune filled ...

Is frozen water scattered in systems around other stars? Astronomers have long expected it is, partially based on previous ...

For years, astronomers have toyed with the idea that the Sun hides an extra planet so distant and dim that even the best ...

"Rings are mostly made of ice and small rocks," said William Saunders, a planetary scientist at NASA's Langley Research ...