Planets

The tiny planet Mercury will be visible from Earth as it moves across the sun, in an event known as a transit.

Beyond the outer edge of the solar system, mysterious, unknown worlds await by the thousands. Astronomers can now finally find these exoplanets. But will we find another Earth?

Two Earth-like exoplanets appear to have smashed into each other in a distant solar system, and the cosmic carnage is only getting worse.

The Nobel Prize in physics has been awarded to three scientists for unraveling the structure and history of the universe and for changing our perspective of Earth’s place in it.

It probably isn't a black hole, if it exists at all. But two physicists think we should check to see if it's a black hole anyway.

Venus, our solar system's broiling, radiation-bombarded, sulfuric-acid-raining, toxic hellscape of a planet, may once have been quite nice, actually.

Often, when we don't have an immediate explanation for something strange in space, some people blame aliens. But better explanations usually come along in time.

Powerful storms have erupted on Jupiter, and they're screwing up the planet's beautiful belts of white and color.

If confirmed, it may be the first "exomoon" discovered.

Pluto lost its "official" planet status over a decade ago, but fans of the solar system's underdog are still rooting for it. And NASA Administrator Jim Bridenstine is one of them.

Study: The moon is very, very, very old.

A 90-mile-wide scar on the Martian landscape is potential "ground zero."

This first-of-its-kind discovery reveals a new category of ultrahot exoplanet, one so thoroughly cooked that your cast-iron skillet would bubble, turn to gas and boil out of the atmosphere.

Moons orbiting distant worlds have a new nickname, and it's even cuter than "moonmoon."

The year goes by quickly for this newfound asteroid.

The debate about 'Oumuamua's nature and origin continues.

The solar system is more than a row of nine circles. Try 18,000 of them.

A NASA mission to an ancient iron-nickel hunk has entered its final design phase, a key milestone on the way to reaching the distant destination in the mid-2020s.