Depth 29 · Star cluster

Pleiades

The Pleiades, or Seven Sisters, is a young cluster of more than a thousand stars in Taurus and one of the most recognizable sights in the night sky. Its distance was the subject of a long-running dispute that Gaia data helped settle.

Fact sheet

Type

Open star cluster

Distance

About 440 light-years from the Sun

Size

The gravitationally bound core is about 23 parsecs (about 75 light-years) across, based on a tidal radius of about 11.6 parsecs

Constellation

Taurus

Position in the sky

Right ascension 3h 47m, declination +24° 07′

Seeing it from Earth

Easily seen with the naked eye from both hemispheres as a small, tight group of stars in Taurus, best in the evening sky around December; binoculars show many more members.

On the voyage

Depth 29, in the Milky Way section of the route, between TRAPPIST-1e and Betelgeuse

Things to know

• The Pleiades holds more than a thousand loosely bound stars, but a handful of bright blue members give the cluster its familiar look. NASA
• People have watched the cluster since ancient times, and Galileo was the first to look at it through a telescope. NASA
• Hipparcos data published in 1997 put the cluster about 10% closer than other methods suggested, which started a long debate. ESA
• Most methods, including radio measurements in 2014, put the cluster 130 to 140 parsecs away, and a 2019 Gaia analysis gave 135 parsecs, siding against the Hipparcos value of about 120. arXiv
• A Hubble image shows a dusty cloud near the star Merope being broken apart by the star's radiation. NASA

Sources

• NASA Science (Hubble) – Messier 45 (The Pleiades)
• Lodieu et al. 2019, A&A – A 5D view of the Alpha Per, Pleiades, and Praesepe clusters (arXiv)
• Melis et al. 2014, Science – A VLBI resolution of the Pleiades distance controversy (arXiv)
• ESA Hipparcos – Pleiades distance