There could be a planet hiding out on the distant frontiers of our solar system. Astronomers have published new details about what it probably looks like.
Find out everything there is to know about planets and stay updated on the latest planet news with the comprehensive articles, interactive features and planet images at LiveScience.com. Learn more about space and the solar system as scientists continue to make amazing discoveries about planets.
The best-ever photos of Ultima Thule have made it down to Earth, and they heighten the intrigue about the frigid and faraway world.
The final photos that NASA's New Horizons spacecraft snapped of Ultima Thule during the probe's epic Jan. 1 flyby reveal the distant object to be much flatter than scientists had thought.
'Oumuamua is long gone, but it's still leaving scientists guessing. A new explanation proposes that the strange object was a "monstrous fluffy dust aggregate" produced by a busted-up comet.
Can you spot our own sun in this map of more than 800 million stars in the area surrounding the Milky Way?
The weirdly clustered orbits of some far-flung bodies in our solar system can be explained without invoking a big, undiscovered "Planet Nine," a new study suggests.
Half a century after the first manned space flight, space travel may be about to enter the age of steam.
The most distant celestial object ever explored may well have moons, and astronomers are trying hard to find them.
Earth is always changing, and 2018 — a year filled with hurricanes, volcanic eruptions and earthquakes — was no exception.
A newly discovered object is the most-distant body ever observed in the solar system — and the first object ever found circling at more than 100 times the distance from Earth to the sun.
It's time to say goodbye to one of the most storied explorers of our age: Voyager 2 has entered interstellar space.
NASA is starting scientific observations of a new asteroid called Bennu today (Dec. 3), kicking the OSIRIS-REx mission into full gear.