Pleiades

The Pleiades (M45) — also called the Seven Sisters — is one of the most spectacular and culturally significant open star clusters in the night sky. Visible to the naked eye even from light-polluted suburbs as a tight knot of stars in the constellation Taurus, the Pleiades has been recognized, named, and celebrated by virtually every human culture that has observed the sky.

The cluster contains over 1,000 confirmed member stars within a region about 8 light-years across, located 444 light-years from Earth. Most people see six stars on a clear night; under truly dark skies, sharp-eyed observers can count 9-12. Binoculars reveal dozens; long-exposure photography reveals the famous blue reflection nebulosity surrounding the brightest stars, where dust drifting through the cluster reflects the intense blue light of the hot young stars.

The brightest stars in the cluster are massive blue B-type stars only 100 million years old — remarkably young by stellar standards, which is why they still shine intensely blue. The cluster itself is also young; it will gradually dissipate as gravitational interactions with the rest of the Milky Way scatter its stars over the next 250 million years.

Culturally, the Pleiades is perhaps the most cross-culturally significant deep-sky object in human history. The Greek myth of the Seven Sisters (daughters of Atlas) gave the cluster its English name. Japanese mythology calls the cluster Subaru — the Japanese car manufacturer's name and six-star logo are taken directly from the cluster. The Australian Aboriginal "Seven Sisters" Dreamtime story has structural parallels to the Greek myth so striking that some scholars argue both descend from a shared myth predating the spread of modern humans out of Africa 100,000+ years ago.

The Pleiades rises in the evening in late October and is best viewed November through March. The cluster is easy to find by following the line of Orion's belt to the right; it stands well above the constellation Taurus.