A week ago, I was looking for the constellation Andromeda in the sky, and now let’s try to find in it that for which novice amateur astronomers are interested in this constellation. So, how to find the Andromeda Nebula in the starry sky?
How to find the Andromeda Nebula in the sky:
In the first method, the null point of your search is a large quadrilateral of stars, called the Pegasus square.
On autumn evenings, Pegasus Square almost does not need to be searched – it will literally catch your eye if you face south and lift your head up. The stars that form the square are not very bright – their brilliance is approximately equal to the stars of the famous Big Dipper’s bucket, but since the stars surrounding the square are not bright either, it literally dominates the evening sky of the second half of the autumn.
Having found the Pegasus square in the sky, you can easily find all the main stars that form the Andromeda figure. Let me remind you that the main pattern of the constellation is a chain of stars extending east from the upper left corner of the Pegasus square, forming together with the square something resembling a gigantic smoking pipe and mouthpiece.
In November in the evenings, Andromeda is very high in the sky.
Now pay attention to the middle star in the chain. This is β Andromeda or the star Mirah. (Problems with Greek letters? Look here for the alphabet .) Above it, you will see two rather dim asterisks – μ and Andromeda. Together, the three stars form the belt of Andromeda. (On medieval maps, the heroine of the ancient myth stands chained to a rock, but … for some reason in a horizontal position!) So, the Andromeda Nebula is located directly above the belt, above the asterisk Andromeda!
The second way is that we are looking for the Andromeda Nebula not from Pegasus square, but from the constellation Cassiopeia, which is almost at its zenith in the autumn evenings.
The constellation of Cassiopeia is extremely easy to find thanks to the characteristic letter W (or M, as you prefer), which it forms in the sky. To see Cassiopeia in the fall, just go outside and look up.
Found a constellation? Now notice that the right half of the sky letter W is sharper than the left. This sharper half of the constellation is an arrow pointing to the Andromeda galaxy.
The distance from the tip of the arrow to the nebula is about four times greater than between neighboring stars that form the letter W of Cassiopeia.
And now you see?
The first thing to say before embarking on a search is that the Andromeda Nebula is not a nebula at all, that is, not a cloud of interstellar gas like the Orion Nebula, but a giant galaxy like our Milky Way and even more. According to the latest estimates, the Andromeda Nebula includes about a thousand billion stars. Approximately every 20th of these stars is similar in its characteristics to our Sun.
Why then did the Andromeda Nebula be so named? This story stretches from the time when astronomers called nebulae any faint, obscure, not resolvable object into a telescope on individual stars, resembling a cloud or a piece of the Milky Way. Later it turned out that some of these objects were distant star clusters, some were indeed clouds of interstellar gas, and some were very distant huge galaxies. But the common name for all has been fixed and is still used, although it is quickly becoming obsolete.
The Andromeda Nebula has official designations. The most famous is the M31 (object number 31 from the Charles Messier catalog) and NGC 224 (the 224th object from the New Common Directory of foggy objects). So don’t be surprised if instead of Andromeda Nebula you read M31, NGC 224 or Andromeda Galaxy.
And what does the Andromeda Nebula look like in the sky?
It depends on where, when and how you look at it. Three factors have the greatest influence on the quality of the observed:
1. Highlights of the sky. Cities have long become a stronghold of light: street lighting is so bright that it successfully hides all faint stars from city dwellers, not to mention nebulae or the Milky Way. In addition, smog often hangs over large cities, which well disperses the light of lanterns and turns even cloudless skies into milk.
2. The height of the Andromeda Nebula above the horizon. At sunrise and sunset, the galaxy is difficult to observe, as the atmospheric absorption of light is high just above the horizon. The best conditions for observing the galaxy are August and September nights, as well as evenings in October, November, and December when the galaxy is very high in the sky.
3. The general condition of the sky. Even outside the city, away from street lighting, the sky may be unimportant. What is important is not the tranquility of the atmosphere, but its transparency. The more transparent and clear the sky above your head, the duller objects you can see on it.
Suppose you are outside the city or at least on the outskirts of the city, and the sky above you is more or less dark and transparent. There are two ways to find the Andromeda galaxy in the night sky.
What if the Andromeda Nebula is not visible?
If the Andromeda Nebula is not visible to the naked eye, you can try to find it with binoculars or a telescope.
Binoculars give a larger field of view, so the galaxy is easier to search for in it. Start the search from the star Mirah (Beta Andromeda), then lead the binoculars through the mu and nude Andromeda. In the city sky, the nebula will appear through binoculars as an indistinct spot just above and to the right of Andromeda nu. Examine this area of the sky slowly. Only outside the city, the smooth, soft glow of the galaxy will be striking.
In the telescope, the search must also be conducted from the star Mirakh successively through mu and nu Andromeda. When searching, use the smallest magnification possible to increase the field of view. In general, large increases are unnecessary for observing galaxies and weak nebulae – they reduce the contrast. Newton owners, keep in mind that your telescopes give an inverted image! Those with telescopes with the Go To function can simply drive the name of a nebula into a computer, and the telescope will hover over it automatically.