What you need
Binoculars
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THIS week, we are taking stargazing to the extreme to spot the most distant object it is possible to see with the naked eye: the Andromeda galaxy.
This spiral galaxy is named after the nearby constellation of Andromeda. Also called Messier 31, M31 or NGC 224, it is between 2.2 and 2.5 million light years from Earth. This makes it the closest major galaxy, and the closest spiral galaxy, to our own. It is the biggest galaxy in the group, a collection of just over 30 galaxies that includes the Milky Way, and it is made up of about 1 trillion stars.
You can see the Andromeda galaxy with the naked eye on a clear night with no moon, even in places with a little light pollution. It has an apparent magnitude of 3.44. If you tested the light pollution in your area earlier in the series (see 鈥�How to measure light pollution where you live by counting stars鈥�), you will know if it is possible to see something with that magnitude in your area.
To identify Andromeda from the northern hemisphere, first find the Great Square of Pegasus. Use the Plough or the Big Dipper to find the North Star, or Polaris (see 鈥�How to find the North Star and Southern Cross鈥�). Then imagine a line from any star in the handle of the Plough, through the North Star, to get to W-shaped Cassiopeia. Continue the line through the Caph star, which is the top right of the W of Cassiopeia. This line will take you to the four bright stars of the Great Square of Pegasus.
In the south, Cassiopeia and Pegasus will be visible to the north just after sunset. Look near the horizon, and you will see the M-shape of Cassiopeia. Pegasus is slightly higher and to the left.
The star at the bottom right of the Great Square in the south, or top left in the north, is Alpheratz. It is also the brightest star in the constellation of Andromeda.
The galaxy sits between it and Cassiopeia. Through binoculars, or looking through a telescope, you can see the spiral arms of the Andromeda galaxy. This amazing sight makes it one of the most popular targets for astrophotographers.
In the northern hemisphere, Andromeda can be seen from August to February. It will appear low on the north-eastern horizon at about 10 pm, then it will climb higher, reaching overhead before day breaks.
In the south, the constellation can be viewed from October to December. This month, it will appear at around 10 pm then fall below the north-western horizon by about 1 am. The exception is places more than 40 degrees south, where Andromeda isn鈥檛 visible because it sits at 41 degrees.
Next week, for the final instalment of this series, I will be showing you how to find Santa鈥檚 sleigh 鈥� aka the International Space Station.
Abigail Beall is the author of The Art Of Urban Astronomy (Buy from *)
To download a printable version of the page click here.
For next week
A clear night
One or more children (optional)
Next in the series
2 How to watch the Leonid meteor shower
3 Venus and Jupiter in conjunction
4 Mercury at its greatest elongation
5 How to see the Northern Lights
6 Find the Andromeda galaxy
7 How to see Santa (the ISS) on Christmas EveIs it a satellite, or a sleigh delivering presents?
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