Did you know that it is possible to see other galaxies in this universe?
Considering the vastness of the universe, we can easily give a call that Andromeda Galaxy lies in the neighborhoods of the Milky Way.
But, then there are many more galaxies in between then why Andromeda is so important to us!
For Milky Way, Andromeda is the closest spiral galaxy – only 2.5 million light years away from us!
Astonishingly, Andromeda is even bigger than our own Milky Way in this universe!
Do you know that the universe that we can see is much larger than we can think of by any estimates? By a rough estimate, the universe is made of over 2,000 billion galaxies. Many of them are tens and hundreds and thousands of million light-years away from the Milky Way!
Our ordinary telescopes cannot view such distant galaxies in this cosmos and for that purpose extremely powerful telescope such as Hubble Space is doing its job in outer space to snap much sharper images of the celestial objects that include galaxies. And, images received from Hubble Space Telescope reveal that the universe is extremely vast than anticipated earlier, only a few decades back!
In this vastness of the universe, the Andromeda galaxy is truly our neighbor by any standards. Andromeda is so vast that light takes almost 200,000 years to map it from one end to the other end of the galaxy and surprisingly, we can see or image the entire galaxy as one complete celestial object!
Andromeda also called M31 in the scientific language falls under a local group of galaxies that also include our Milky Way and around 50 other galaxies in our neighborhoods. Almost 1,000 billion stars constitute Andromeda galaxy, which is two times higher than the numbers of stars believed to be in Milky Way!
Andromeda Galaxy possesses two spiral arms and at least 450 globular clusters orbit around the galaxy. Many of them are said to be the most densely populated clusters.
But, what is so special about spiral galaxies?
A bulge at the center with a flattened disk and spiral arms are the main features of spiral galaxies. Bulge is made of redder and older stars. While yellow stars such as our Sun can be seen across disk and arms. The entire disk rotates like a whirlpool or a hurricane!
In contrast, Elliptical galaxy does not have any disk or arms. An oval-shaped or ball-kind appearance is the cornerstone of elliptical galaxy and stars do not revolve around any center!
You may be surprised to know that in a pitch dark sky we can see Andromeda even by our naked eyes! But it appears so faint that we need special efforts if we want to view it by naked eyes!
That is why a clear sky – free of air and light pollution with extreme dark– is necessary when you attempt to find Andromeda through naked eyes. Always remember that Andromeda is at least 6-7 times as large as the full moon that we see regularly.
But the question remains which part of the sky to search for to see Andromeda?
For this, you have to locate a huge W like figure in Cassiopeia constellation in the sky!
Draw an imaginary line between the lowest point in W and the left lower corner of the famous square of Pegasus. You will find Andromeda in and around the top one-third portion of this imaginary line. Firstly, try to locate it through binoculars and then use 4″ or 6″ telescope to see a sharper version of it.
You can then clearly view the spherical structure of Andromeda!
Ideally, you should not use a telescope with aperture size more than 4-6 inch as it will restrict your field of view.
In the center of Andromeda, you will find a concentrated pouch of matter with arms stretched in spirals full of stars, gas, and dust.
Can you guess how many stars constitute Andromeda Galaxy, roughly?
Overall, Andromeda is said to have contained over a billion stars that counts almost four times as much as found in the Milky Way.
Yet you will be surprised to know that our Milky Way is more massive than Andromeda?
How can it be so?
That is because Milky Way contains much more Dark Matter than that is contained in Andromeda!
But, by the way, do you know anything about the Dark Matter?
Dark Matter and Dark Energy are two mystical substances found in this cosmos, and they are invisible by any means, tools, equipment or sensors available at our disposal so far!
You may be surprised to know that all visible matter including all stars, nebulas, planets, etc. constitute only 5% of the total matter; remaining all is either Dark Matter or Dark Energy!!
The scientists define Dark Matter as a dense cloud of Weakly Interacting Massive Particles (WIMPS). While they do not interact with normal matter, they exert a gravitational force and are the source of gamma rays radiation in our universe.
Scientists have noticed the strong signals of gamma-rays emitting from the center of Andromeda. Similar signals come from the innermost regions of the Milky Way too. These signals provide a clue to the presence of Dark Matter in these galaxies.
Due to the presence of Dark Matter, Andromeda and Milky Way are moving closer and closer.
Images from Hubble Telescope reveal that Andromeda is moving toward the Milky Way at the speed of about 6000 kilometers per minute.
Astrophysicists estimate that these two galaxies will merge in 4.0 to 4.5 billion years from now.
Dark Energy is the antigravity force evenly distributed throughout the universe causing faraway galaxies to move apart on a continued basis.
Unlike Dark Energy, Dark Matter is not evenly spread throughout the galaxy or universe, but it is believed to have accumulated in the centers of the galaxies whether Andromeda or Milky Way.
That is why powerful gamma-ray signals continue to emit from the center of Andromeda and Milky Way all times!
The merger of Andromeda with Milky Way will not occur at once but will take at least 2 billion years before both the galaxies merge completely!
No surprise that during the time of merging our Sun will get displaced from its current location keeping all its planets intact!
It is a different thing that by that time our Earth might not remain habitable for several other reasons!
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.