Stardate:07:19:98
The Andromeda Galaxy.
The name alone conjures
images of the strange, distant, and bizarre. It is the most distant object
visible to the naked eye. The light that reaches us today from its distant
suns was generated nearly three million years ago when small, clever primates
were still new on a distant world that would one day be known as Earth.
What looks to be just a dim, fuzzy patch in the sky is
ablaze with the light of perhaps 400 billion suns. We know now that in
our galaxy at least, most stars seem to be accompanied by planets. It seems
more than likely that is also the case with Andromeda as well. How many
of those suns warm planets awash with life is anybody's guess.
This enigmatic island of stars can be found fairly easily
this week, provided you view from an area with a low horizon to the northeast.
It will be found exactly northeast just a few minutes, before 10 p.m. this
week. Look for the Andromeda galaxy 14 degrees above the "true horizon."
The true horizon is simply where the horizon would be if there were no
obstructions in your way. By sunrise, the Andromeda Galaxy and its accompanying
galaxies will be nearly directly overhead, centered just one degree to
the north.
At magnitude 3.5, the Andromeda Galaxy is an easy find
from any dark sky, even without the use of an optical aid. Also, it is
seen nearly three degrees across, making it one of the easiest deep sky
objects to view. It appears as large across as six full moons placed side
to side!
A pair of binoculars with a large objective (main) lens
is the perfect instrument with which to view the Andromeda galaxy, or a
rich field telescope having a focal ratio between f/4 and f/8. A typical
telescope will show only the galaxy's bright central core.
Andromeda is a perfect example of a typical spiral galaxy.
Our own galaxy, the Milky Way, was long thought to be another spiral galaxy,
much like the Andromeda Galaxy. However, new evidence seems to suggest
that the Milky Way is most likely a barred spiral.
Most astronomy textbooks will list the distance to the
Andromeda Galaxy as 2.3 million light years. We now know it is even more
distant than that, and the revised distance is now believed to be 2.9 million
light years.
Measurements of the spectrum of the Andromeda galaxy reveal
that the galaxy is rotating at 300 km/sec. That is 675,000 miles per hour.
Galaxies cluster themselves into groups because of gravitational
attraction, and our Local Cluster (as it is known) has two subclusters,
one centered around the Milky way, the other around the Andromeda Galaxy.
Two small galaxies can be seen fairly close to Andromeda,
M32 and M110. The Andromeda Galaxy itself has the designation M31.
M32 is the smaller of the two, and is slightly below M31.
This small round galaxy is also known as NGC 221. It is magnitude 8.2,
and appears about 1/8 of a degree across, dwarfed by its larger companion.
M32's bright central core is its distinguishing feature.
Slightly above M31 is M110. This is a spiral galaxy, looking
like a smaller version of M31. It stretches more than 1/4 of a degree across
and is slightly brighter than M32, at magnitude 8.
All three of these galaxies can be found within one degree
of each other, making this cluster of galaxies a favorites of amateur astronomers
throughout the northern hemisphere.