amateur astronomers like to work with "Observing
Lists" to help guide their night-time observing
sessions. From lists for beginners to lists of hard-to-find
objects, there are lists for everyone.
Star Finder star map has round circles around 10 objects.
These are special objects which are visible either by
the naked eye, or through binoculars. Of course, the
higher magnification of a telescope gives even more details.
more about these targets:
- Mira is
a red super giant star which significantly changes
in brightness. Many amateur astronomers measure the
brightness of variable stars; that helps professional
astronomers better understand stars. The
AAVSO website shows how to do this. The distances
to galaxies can be found by observing the brightness and periods
of variable stars.
Nebula M42 can be seen with the unaided
eye from a dark location or in binoculars from
the city. Located just below the belt of Orion,
it is a huge cloud of dust and gas. Gravity is
pulling it into clumps which eventually ignite
as stars. It glows because of bright stars which
have already formed in it.
M45 is an open star cluster. This
has many hundreds of stars which all formed from
a nebula at roughly the same time. The Orion Nebula
will become an open cluster in a few million years.
This is a good test of eyesight. Some people can
see 7 or more stars.
Cluster M44 is another open cluster.
Hercules Cluster or M13 is
a globular star cluster. It has hundreds of thousands
rather than hundreds of stars, and is shaped like
a sphere rather than flat like our solar system
and many galaxies. Globular clusters are some of
the oldest things in the universe.
The distance to each globular cluster can be found
from variable stars. Much of this work was done
at the David Dunlap observatory by Dr. Helen Hogg.
From those distances, astronomers figured out the
shape of the Milky Way, and our distance from the
Coat Hanger cluster is a group of
unrelated stars which look like a coat hanger.
This is in a star rich part of the Milky Way.
Galaxy or M31 is the most distant
object most of us can see with our naked eyes.
It has spiral arms, just like our Milky Way. There
is a black hole in the centre. Almost all galaxies
are moving away from us. This galaxy, however,
is moving towards us and may pass through the Milky
Way in 2 billion years. The Andromeda Galaxy, the
Milky Way plus a few other galaxies form the local
groups of galaxies. There are other clusters of
galaxies in Virgo and Hercules, but telescopes
are needed to see them.
- Mizar and Alcor form
a double star. Some people with good vision can see
that the middle star of the Big Dipper handle as a
double star. Each of these is a double star with the
stars orbiting each other. Almost half of solar systems
have multiple stars. If Jupiter had
been 90 times heavier, it would have ignited and formed
into a second star. Then we would have had less night.
Double star systems still have planets, but probably
not as many.
Cluster is two separate open clusters
next to each other. One cluster is about 3 million
years old, the other almost twice as old.
is a fairly bright star which you would see straight
overhead if you lay on your back at the North Pole.
It stays in same spot of the sky, always within about
a degree of true north. It is easy to find from the
pointer stars of the Big Dipper. Some find North at
night by finding Polaris. It is also used by amateur
astronomers to adjust the alignment (polar align) of
their telescopes. There is no bright star directly
above the South Pole.