Planetary Science

The moon may have melted 4.35 billion years ago—explaining a lunar age mystery

Material from asteroid Ryugu riddled with earthly microbes provides a cautionary tale for scientists seeking signs of alien life

If there’s a hidden world in the solar system, a new telescope should find it

“Twilight rays” are but one of several viewing treats for the liminal time between day and night

Samples from the far side of the moon gathered by China’s Chang’e 6 mission record eons of tumultuous lunar history

The nearby star Vega, featured in the 1997 movie Contact, appears to have a smooth disk devoid of giant planets for reasons we can’t explain

Finding a perfect sphere is actually pretty difficult

The Martian new year arrives with the Red Planet’s vernal equinox. Explaining why requires a deep dive into celestial mechanics and Earth’s calendrical history

At dusk and dawn, the sky dances with three phases of in-between light

A gigantic space rock that slammed into Earth more than three billion years ago grievously wounded the biosphere—and then helped it heal

We have been adding “leap seconds” to time kept by our atomic clocks, but soon we may have to subtract one. Are the tiny adjustments worth the bother?

For the first time, we are sending a spacecraft to explore an alien ocean world—a moon that might host life today