Twinkle, twinkle, little black hole. The High Altitude Water Cherenkov observatory has released its first map of the sky, including the first measurements of how often black holes flicker on and off.

The Nebra Sky Disk, a 12-inch copper disk with inlaid celestial representations, is debated as either the oldest known concrete representation of astronomical phenomena (circa 1600 B.C.) or a later ...

For as long as humans have looked upward, the night sky has been our compass ... These tools condensed centuries of observation into portable maps. With them, astronomers could predict planetary ...

Mercury is a "morning star," most favorably placed for observers in the Southern Hemisphere. Maximum elongation from the sun is on the 24th. Venus is an "evening star" in the southwestern sky just ...