A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth ...

Could a lonely planet wander aimlessly through the restless galaxy change the subtle dance of gravity within our solar system ...

How can we figure out if the planet is actually there? And will it even be bright enough to see? Here are some answers to these and other pressing questions. Others aren’t quite so sure. “I’m very ...

Tiny crystals in Earth’s crust may have recorded meteorite and comet impacts as our planet traveled through the spiral arms ...

Venus has long been called a dry, hellish planet veiled in clouds of liquid acid. But new study of old spacecraft data tells ...

The methane gas may constitute a rarefied atmosphere, or it may come from erupting plumes on Makemake’s surface.

One way that astronauts have been fighting bone loss is through strength training. And they're getting some help with a new machine delivered this week by the shuttle Endeavour, which docked with the ...

A fleet of ball-shaped rovers could drift across the Martian surface like tumbleweed, driven simply by the wind.