What is the furthest object you can see with just your eyes? You can name a local building or point to an airplane flying overhead. You might even guess the name of a distant star, but an astronomer will give you a different answer: the Andromeda galaxy.
How far is it? The Andromeda Galaxy is a staggering 2.5 million light-years away, but it's still one of our closest galactic neighbors.
For comparison: our sun (which is actually the closest star to earth) is only 8 light minutes away. Most of the brightest stars in the sky are less than 100 light-years away.
The perfect time to see the Andromeda galaxy
The galaxy is named for the constellation it is in, Andromeda the Princess. Both the constellation and the galaxy are visible from most of the world, but unfortunately not all year round. If you want to see this galaxy for yourself, the fall months of September through November are the best time.
During these months, the constellation and galaxy may rise in the east around midnight. (From the northern hemisphere, it can be seen quite high on the southern horizon around midnight in early October.)
Methods to find the Andromeda galaxy
There are several ways to find the galaxy. If you have a computerized GoTo telescope and you know how to use it, you can just tell it to find the galaxy in the sky. If you live in the suburbs of a big city or town, this might be your only option as the galaxy is pretty dark. (Thus theLight pollution from nearby polescan light up the sky and drown out all but the brightest stars.)
You can also use one of the many free smartphone apps that identify objects in the night sky. For example, if you're using an app like Star Walk or SkySafari, you can point your phone at the sky and it will identify the stars and constellations for you.
However, it's much more fun to find a dark place far from a city and scour the galaxy on your own. To find it, we must first find the constellation in which it is located.
Ursa Major Tracking
Many people are familiar with Ursa Major (or Plow in Britain), the seven brightest stars in the Ursa Major constellation. Two of these stars, Merak and Dubhe, are known to point toward Polaris' north pads. We can also use the constellation to help us locate Andromeda.
In the fall, these stars are very low on the northern horizon, and the further south you live, the lower they appear. If you live in the southern United States, you may not see them during these months.
Because of this, it's best to go out at a different time of night and identify the stars of the Big Dipper before attempting to locate Andromeda. In September, try looking northwest as soon as the sky is dark (around 8 or 9 p.m.). In October and November, the stars are near the lowest point of the northern horizon. During these months, you'll need to get up early just before sunrise to see them rise in the northeast.
This is necessary because first we need to use the stars to locate Polaris. Then we can locate another constellation, Cassiopeia, located next to Andromeda in the sky.
After finding the Big Dipper, draw a line through Merak and Dubhe toward Polaris. Continue drawing the line through Polaris and you will reach Cassiopeia. Looking north in the fall months it appears almost overhead as a crooked M.
After the Pursuit of Cassiopeia
Keep an eye on Cassiopeia and turn around so you're facing south. The M is now inverted and appears as a flattened W. Tracing a slightly curved line from Ursa Major through Polaris takes you to Caph, the rightmost star of the W.
Now look in the lower left corner at Shedir, the second brightest star in the constellation. Draw a line through Caph and Shedir to the nearest bright star and you will reach Almach. This star appears at the end of a series of stars that make up the constellation Andromeda.
Return to the middle star in Cassiopeia; This star has no name and is known simply as Gamma. If you draw a line through Gamma and Shedir you will reach the other end of the constellation and the great square of Pegasus.
The star in the upper left corner of the square actually belongs to Andromeda and is commonly known as Alpharatz. If you look closely, you'll notice that Alpharatz and Almach appear on opposite ends of a slightly curved line of stars. These are the brightest stars in Andromeda.
Now count two stars to the left of Alpheratz, the star in Pegasus Square, and you come to the rather bright star Mirach. (You can just look at a star to Almach's right, but the gap between the two is pretty big. It might be easier to jump away from Alphaheratz instead.)
Can you see a fainter star over Mirach? It's not a particularly bright star, and suburban stargazers can have a hard time spotting it. (If you have binoculars, they should appear in the same field of view as Mirach.)
This fainter star is unnamed but has the designation Mu Andromedae. We're almost there, but we have to jump to another star. Look again, this time over Mu, and you'll see an even fainter star. Known as Nu Andromedae, this is the closest star to the Andromeda galaxy.
(If you're looking under suburban skies and are having trouble locating Mu, Nu, things get harder. Again, if you have binoculars, the pair will appear in the same field of view.)
Observers under clear, dark skies, far from city lights, may have already seen our target. It appears as a small fuzzy gray speck in the sky just above Nu Andromedae. If you live on the outskirts of a city and nearby buildings block streetlights, you can still see it. Unfortunately, if you live in the suburbs of a city, you may be out of luck.
Andromeda galaxy in a telescope
Many years ago, long before our city lights polluted our skies, the galaxy was a relatively easy target for astronomers. In fact, it has been widely observed and studied for over a thousand years. The Persian astronomer Abd al-Rahman al-Sufi made the first recorded observation of the galaxy in AD 964 and described it as a "small cloud".
Our eyes are sensitive enough to see the brightest part of the galaxy. In comparison, the photographs show their true nature and it is an impressive sight. If we could see the entire expanse of the galaxy with just our eyes, it would appear almost six times larger than the full moon. Imagine living closer to the edge of our Milky Way and being able to see the Andromeda galaxy stretching across the sky!
If the plain eye view is a little daunting, use binoculars. With just 8x32 binoculars, the galaxy appears as a light gray oval patch in the sky. Try looking at it with an oblique view; in other words, focus your gaze on a nearby star (e.g. Nu Andromedae) and try to look at the galaxy as if you were looking "out of the corner of your eye". Viewed this way, the spot becomes more elongated and the core appears about twice as bright as the elongated part.
Telescopes, even small ones, can reveal much more, and it's definitely worth investing time to discover the deeper details. At first glance it looks like an elongated gray band with a relatively light ovoid core. On one long side, the galaxy appears to be fading, while the other long side has a more defined edge.
A moderately small telescope can show two slightly obscured bands crossing the core on the sharp side of the galaxy. These two bands are the spiral arms of the galaxy seen almost edge on. With a much larger telescope, the arms are more visible and can appear well defined.
M32 and M110 satellite tracking
If you're missing the galaxy's arms, try looking for its two tiny satellite galaxies. Astronomers also know the Andromeda galaxy as Messier 31 (or just M31); In other words, it was number 31 in a catalog of "deep sky objects" published on January 18, 2007ºFrench Astronomer of the Century, Charles Messier.
The two satellite galaxies are known as M32 and M110. Both are very small and faint and difficult to see with binoculars. Luckily, both can be seen with a weak telescope. Of the two, the M32 is brighter and easier to track.
It appears on the long side of the galaxy, which has a gradually fading rim. It may not be obvious at first, but it looks like a very small, almost circular nebula with a star-like core.
The M110 is larger but dimmer, so its light is more diffused, making it harder to see. Find it on the other side of the galaxy from M32 (the side with the most clearly defined edge) and 1.5 times as far from the core of the Andromeda galaxy. If you see a small, faint oval spot, you've found M110.
Both satellite galaxies appear in the same field of view at low magnification, but neither shows anything interesting. In this case, the fun comes more from pursuing your goals than from the magnificence of the prizes themselves.
Conclusion - The meaning
Keep this in mind as you gaze out into deep space: the Andromeda galaxy is about 200,000 light-years across and is said to contain about a trillion stars. It is more than twice the size of the Milky Way.
Light from the galaxy took about 2.5 million years to reach us. You see what it was like when our first ancestors started making stone tools in Africa. Perhaps they too looked up and marveled at this "little cloud" between the stars.
We may not be able to travel through time and space, but the Andromeda galaxy is a window and stepping stone into the past. Just as your ancestors once unknowingly gazed upon this distant citadel of stars, so can you.
It's best to find Andromeda in fall in the Northern Hemisphere, where it can be seen from dusk until dawn. In late September and early October M31 rises in the eastern sky. It's overhead around midnight and still high in the west as it fades into the morning's dawn glow.How do you find the Andromeda Galaxy? ›
Most people find the galaxy by star-hopping from the constellation Cassiopeia the Queen, a very noticeable M- or W-shaped pattern on the sky's dome. You can also find the Andromeda galaxy by star-hopping from the star Alpheratz in the Great Square of Pegasus. Both methods will lead you to the galaxy.How do I find Andromeda Galaxy at night? ›
Locate the Cassiopeia constellation.
This is called Polaris or the North Star. Across Polaris from the Big Dipper will be Cassiopeia. Cassiopeia contains five stars in a “W” shape. The right side of this "W" will point down directly at the Andromeda Galaxy.
From mid-northern latitudes, you can see Andromeda – M31 – for at least part of every night, all year long. But most people see the galaxy first around August or September, when it's high enough in the sky to be seen from evening until daybreak.What time should I photograph Andromeda? ›
You do not need a telescope to photograph Andromeda. because it is such a large deep-sky object, a telephoto lens (or zoom-lens) will suffice. When it comes to photographing this galaxy, this most important factor is to shoot during the New Moon phase, and away from city light pollution.