Milky Way’s ‘ultra-faint dwarf galaxies’ help probe early universe

Ultra-faint dwarf galaxies preserve clues to early-universe conditions, acting as cosmic fossils. Simulations show whether they formed stars or stayed dark.

Waves on other planets vary widely, new MIT study suggests

A new study from MIT suggests that waves on other planets should vary greatly. Scientists are looking at the lakes and seas of Saturn's moon Titan for clues.

How much water on exoplanets does life need?

Astronomers think water is essential to life as we know it. So how much water on exoplanets does life need? A new study suggests 20-50% of Earth's water.

Here’s how to see the Lunar X and V at 1st-quarter moon

Lunar X and Lunar V are optical features on the moon. They are visible through a telescope for several hours around the time of the 1st quarter moon.

Black hole Cygnus X-1 has fast, powerful dancing jets

The Cygnus X-1 black hole emits jets that are bent by stellar winds from a companion star. This has enabled astronomers to calculate the power of those jets.

Summer solstice in Mars’ southern hemisphere is April 25

The summer solstice in Mars' southern hemisphere happens on April 25, 2026. Summertime there typically kicks off dust season on the red planet.

Happy Earth Day! Why do we celebrate it on April 22?

April 22 is the date of Earth Day in part because of Arbor Day, an earlier observance. The focus for 2026 is "Our Power, Our Planet."

A pileus cloud means bad weather is on the way

A pileus cloud looks like a curved, white cap on the top of a towering cumulus cloud. Pileus clouds are a sign that bad weather is on the way.

Meet M13, the Great Globular Cluster in Hercules

Many stargazers call it the finest globular cluster in the northern half of the heavens. It's M13, also known as the Great Globular Cluster in Hercules.

Small ants clean larger ants in a surprising twist of nature

Small ants clean larger ants, a researcher has discovered. It's the first known case of interspecies grooming between ants.