|Messier 45 - the Pleiades in the constellation Taurus in a
The Pleiades - also
called the Atlantiads, the Atlantiads and the Seven Sisters - is an open star
cluster, already visible with the naked eye in the constellation of Taurus. In
the Messier catalogue it is called M 45, named after the Pleiades from Greek
The 7 brightest stars
are named after figures from Greek mythology, the Titan Atlas (hence
Atlantides), his wife Pleione and their seven daughters Alkyone, Asterope,
Celaeno, Elektra, Maia, Merope and Taygete. The Pleiades, who can be classified
as nymphs, raised Dionysus and Zeus together. According to mythology they were
pursued by the sky hunter Orion. Zeus moved the Pleiades to the sky as a
constellation, but even there they are still pursued by Orion, whose
constellation is located about 30° southeast of the Pleiades.
In the NGC catalogue the Pleiades
are not listed separately, but there are several reflection nebulae with their
own NGC numbers in the Pleiades area. These include the Maja Nebula (NGC 1432)
and the Merope Nebula (NGC 1435). Only about half a minute of arc from Merope
is a concentration of interstellar dust known as IC 349 or Barnard's Merope
Pleiades appear with an extension of about 2° about four times as large as
the moon seen with the naked eye. The star cluster is about 445 light years
away from the solar system and contains at least 1200 stars which are on
average about 125 million years old. Thus it is one of the youngest open star
clusters in our Milky Way and due to its proximity to the solar system also one
of the best explored.
« Click here or the thumbnail to load a large annoted image
and a size comparison to the full moon.
A more detailed image of us, taken with a longer focal
is shown here.
The blue reflection nebulae surrounding the bright Pleiades stars are
not the remains - as long suspected in the past - of gas and dust from which
the stars were formed. The star cluster is
passing through a molecular cloud known as the Taurus-Auriga dark nebula
complex. The original remnants of dust and gas that would have remained after
the Pleiades stars formed would have completely dissolved in due to the
enormous radiation pressure of the stars a long time ago.
Pleiades are at present in collision with a cloud of interstellar gas and dust.
Such interstellar clouds of matter always appear as brownish coloured nebulae
away from bright stars, illuminated by the stars of the immediate vicinity. In
this case, the bright Pleiades stars ensure that their blue light is scattered
by the dust of their immediate surroundings, thus turning the Pleiades nebulae
into prominent reflection nebulae.
In many prehistoric cultures the Pleiades were considered a special
asterism. For example, a group of six drawn points in the caves of Lascaux is
interpreted as a representation of the Pleiades.
A very important object
from Central Europe, probably used for astronomy, is the so-called Nebra Sky
Disk. A group of seven closely spaced points are identified as the Pleiades.
Here you will find a comprehensive article in german
language (information in english language) on the astronomical
interpretation of the Nebra Sky Disk. It is dated to an age between 3700 and
« The Nebra Sky Disc. Credit: https://commons.wikimedia.org/wiki/File:Nebra_Scheibe.jpg