The Swan Nebula (M17) glides through the early-morning sky near the border that Sagittarius shares with Scutum and Serpens ...

The most recent measurement of a nearby galaxy cluster is deepening a disagreement about how fast the universe is expanding — ...

Fabricius noted the brightness of Mira on August 3, 1596. But when he observed it on the 21st of that month, it was a ...

The Iris Nebula (NGC 7023) is an odd reflection nebula surrounding a magnitude 7.4 star, SAO 19158, in the constellation ...