M45 is technically known as a galactic or open star cluster which describes their location within the general area of the disk of our galaxy the Milky Way. This differentiates them from the much larger and denser globular clusters which populate the outer fringes and halo of the Milky Way.

It contains about 500 stars and at a distance of about 400 light years, is one of the nearest of its type.

The Pleiades Star Cluster is more commonly known as the "Seven Sisters". To many, it appears like a very small dipper. Unfortunately, those of us "blessed" to live in developed countries whose night skys have been destroyed by rampant light pollution are most fortunate to see even six of these ladies.

Seeing as many stars as possible seems to have been a game played since antiquity and the records range up to 16. One sharp eyed observer even charted 14 before the invention of the telescope. On the chart below, I have named and numbered the 8 brightest stars in their order of brightness.

How many can you see?

1 Alcyone magnitude 2.86
2 Atlas magnitude 3.62
3 Electra magnitude 3.70
4 Maia magnitude 3.86
5 Merope magnitude 4.17
6 Taygeta magnitude 4.29
7 Pleione magnitude 5.09
8 Celaeno magnitude 5.44

This was a 30 min exposure with the MX5C and a 135mm lens operating at F 5.6.

Many of the stars in the Pleiades are surrounded by nebulosity that looks strikingly like Earthbound cirrus clouds. It is not clear just what these clouds are or why they exibit the structure they do but it is probable that they are clouds of dust. They display the same spectra as the stars so it is presumed that the clouds are simply reflecting the starlight. The diameter of the cloud surrounding Merope is about 3 light years or nearly the entire distance from the Sun to it nearest neighbor star.

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This photo was a 30 minute exposure with the MX5C through the 16" Newt.

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