Star Atlas
[1] The night sky in winter, centred
on the constellation of Orion, under a
brilliant Moon.
[2] The Pleiades cluster of stars lies at
a distance of about 440 light years from
us in the direction of Taurus, the Bull,
which makes it the closest star cluster
to Earth. The cluster spans about 43
light years. (ESO/S. Brunier.)
Orion can also help us to find Procyon in the Little Dog, and the Twins,
Castor and Pollux. Leo the Lion is rising in the East and will be better seen
in Spring, while the Square of Pegasus is descending in the West and will
dominate the sky next Autumn.
The two brightest stars currently visible in the northern hemisphere of the
sky are Capella in Auriga and Vega in Lyra, the Lyre. Both are circumpolar
from the UK or the northern United States, though when at their lowest they
skirt the horizon.Meteor Showers
There are several meteor showers visible in the winter months from the
Northern Hemisphere and, if the Moon and weather work in your favour,
these can put on an amazing display against the dark skies of winter. Of
these the most reliable is the Geminid meteor shower, radiating from a point
near the twins. The shower begins on 7 December and lasts until the 19th
with peak activity around the 13th/14th. They are particularly rich: as many
as 100 naked-eye meteors can be seen every hour, though strong moonlight
will deplete their numbers. We also have the Ursids, radiating from the
Little Bear (Ursa Minor). This shower begins by 17 December and ends on
Christmas night, it is not generally rich, but is well worth looking out for as it
rises to a peak on 22/23 December.
Bright comets are not easy to predict, and at the time of writing, none
are expected for a while yet. Of course a really brilliant comet may actually
appear at any time.Belt. Extending southwards from the belt is the misty Sword, and the Great
Nebula in Orion, a stellar nursery where fresh stars are being formed. It
is easily resolved with the naked eye and binoculars show it well. It is a
favourite target for astronomical photographers.
In the other direction, upwards (in the northern hemisphere), the Belt
stars point to the orange Aldebaran in Taurus the Bull, and extending from
Aldebaran is a v-shaped cluster of stars known as the Hyades. Actually,
Aldebaran is not a true member of the Hyades, it simply lies about midway
between the cluster and us. Beyond Aldebaran we come to the Pleiades, the
Seven Sisters, the most famous of all star clusters. With the naked eye it is
possible to make out at least seven individual stars and really keen sighted
people can see more. It is said that the record is 19!
Almost overhead on winter evenings lies the brilliant Capella in Auriga, the
Charioteer. It is slightly yellow in colour and is actually four stars in two binary
pairs; the two components are much too close together to be separated with
the naked eye or even with a moderate sized telescope.
Close to Capella is a triangle of much fainter stars known as the Heidi, or
Kids. At the apex of the triangle is the remarkable Epsilon Auriga, normally
of the third magnitude, but every 27.1 years it is eclipsed by a much fainter
companion and drops to the fourth magnitude and remains faint for over a
year until it recovers. In a southward (downward) direction, the three stars of
Orion's Belt point to Sirius, the brightest star in the sky. It is a pure white star,
and when near the horizon it appears to flash various colours because of
atmospheric effects.
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