Charles Q. Choi

Catastrophic floods from overflowing lakes on early Mars may have carved out many of the Red Planet's valleys, a new study finds.

Astronomers may have captured the best view yet of matter colliding with the surface of a young star, findings that may shed light on what the sun looked like in its youth.

Astronomers have uncovered evidence of explosions triggered by dead stars ramming into live stars, possible proof of a new type of supernova, a new study finds.

Mysterious repeating pulses of radio waves may come from a hitherto unknown kind of extraordinarily powerful cosmic magnet, and not pairs of stars as previously suggested, a new study finds.

Bright reflections that radar detected beneath the south pole of Mars may not be underground lakes as previously thought but deposits of clay instead, a new study finds.

A fizzled example of a gamma-ray burst, the most powerful kind of explosion known in the universe, suggests these outbursts can be surprisingly brief, researchers say.

In the wisp-thin sky of Jupiter's moon Ganymede, the largest satellite in the solar system, astronomers have for the first time detected evidence of water vapor, a new study finds.

A mysterious whiff of an unstable chemical in the skies of Venus may not be a sign of life but the result of explosive volcanic eruptions, a new study finds.

Mysterious flares of X-rays from Jupiter's auroras suggest that the giant planet's "northern lights" may possess unexpected similarities with those of Earth, a new study finds.

A cluster composed of thousands of stars may dissolve to become a mob of dozens of black holes in a billion years.

Astronomers may have discovered the smallest and heaviest white dwarf star ever seen, a smoldering ember about the size of our moon but 450,000 times more massive than Earth, a new study finds.

Astronomers may have finally discovered convincing evidence of an elusive kind of supernova, called the electron-capture supernova, that may explain the Crab Nebula.

Tendrils of galaxies up to hundreds of millions of light-years long may be the largest spinning objects in the universe, a new study finds.

E.T. could also potentially have detected life on Earth, scientists say.

Boulders on asteroids can be three-quarters hollow or more, a discovery that could help yield insights on the way in which Earth and other planets formed, a new study finds.

Metal atoms have surprisingly been discovered in the frigid atmosphere of the first known interstellar comet to visit our solar system, a new study finds.

Evidence of what may be the youngest eruption seen yet on Mars suggests the Red Planet may still be volcanically active, raising the possibility it was recently habitable.

The famous equation used to search for alien civilizations has now inspired a new formula to hunt for alien artifacts within our solar system.

Mars did not dry up all at once, but fluctuated between dry spells and wetter times, a new study finds.

The first known interstellar comet to visit our solar system may be the most pristine ever found, never passing near a star until visiting our own, researchers say.

Electric thrusters for spacecraft are increasingly shrinking, and could prove key for new interplanetary missions, experts say.

'Oumuamua, the first known visitor from interstellar space, was likely a pancake-shaped chip off a Pluto-like world.

Oceans' worth of water may remain buried in the crust of Mars, and not lost to space as previously long thought, a new study finds.

Mercury may not have shrunk nearly as much as scientists previously thought, potentially solving the mystery posed by the planet's continuing quakes.

The Mars moons Phobos and Deimos have been born from the remains of a larger moon that shattered.