Libra, a constellation and the seventh sign of the zodiac. The sun formerly entered Libra in autumn, when days and nights balance each other in length. The name Libra, meaning The Balance, probably refers to this fact. Libra is bordered by Serpens Caput on the north, by Ophiuchus and Scorpius on the east, by Lupus and Hydra on the south, and by Virgo on the west. Its brightest star, with a magnitude of 2.61, is Beta Librae, or Zubeneschamali. Alpha Librae is a double star whose components have magnitudes of 2.76 and 5.15.
It's tough to wrap your mind around a time when the Earth wasn't here. So how do Earth and the rest of the planets out there get their start in the universe?
It wasn't so long ago that astronomers thought the universe contained normal matter, or baryonic matter, the base unit of which is the atom. But when it comes to the cosmos, there's always more than meets the eye. What else is hanging out in space?