The major planets in our solar system orbit, more or less, in a single plane. That's why you can look for them along the same sky path traveled by the sun and moon. Is the same true for exoplanets in distant solar systems?

Here's an alternative explanation to the Planet 9 hypothesis, the idea that a large undiscovered planet in the outer solar system is pulling on some small outer worlds, distorting their orbits.

Skywatchers! Check out this first video in the Chasing Darkness series, a stargazing destination guide. This episode - dark sky preserves in Alberta, Canada.

New clues from fossils from the oldest soils on Earth suggest that multicellular, land-dwelling organisms might have emerged much earlier than we thought.

Astronomers are arguing over a brief and unusual flash in the night sky from earlier this year. The call it the Cow. One group argues it was a monster black hole shredding a passing star. The other argues it might have been a black hole being born.

A new study analyzes pulses of radio waves coming from a magnetar - a rotating, dense, dead star with a strong magnetic field - located near the supermassive black hole at the heart of the Milky Way.

New evidence suggests that dark matter - the mysterious stuff that makes up a significant percentage of the universe's mass - can heat up and move around.

Researchers have said that Totten Glacier, a behemoth with enough ice to raise sea levels by 11 feet (3.4 meters), appears to be melting. Now, they say 4 glaciers west of Totten, and a handful farther east, are also losing ice.

New Horizons is the spacecraft that sent back those amazing images of Pluto in 2015. Ultima Thule is its next target, a billion miles beyond Pluto. The encounter is New Year's Day, but start watching now!

Only 2 other fossil clouds are known in our universe, and both were serendipitous discoveries. Then astronomers began searching for these rare relics, and found one!