Ultra-faint dwarf galaxies, cosmic 'ghost towns,' offer new insights into the early universe and star formation.

Carl Sagan told us that there are more stars in the universe than there are grains of sand on all of the Earth's beaches. At the same time, there are more H 2 O molecules in just 10 drops of water ...

The visible universe—including Earth, the sun, other stars, and galaxies—is made of protons, neutrons, and electrons bundled together into atoms. Perhaps one of the most surprising discoveries ...