Beginner's Guide To Galaxies

Mention galaxies to someone and the chances are they’ll imagine a huge, spinning vortex of stars in space - but the reality is that galaxies are so much more than that. For example, if you were to ask those same people how many stars are in a galaxy, they might guess that there are probably millions or even billions of stars, but they might be surprised to learn that many galaxies contain hundreds of billions of stars.

More than that, there could be trillions of planets in every galaxy, not to mention nebulae, star clusters, black holes, pulsars, neutron stars, and even strange, powerfully magnetic neutron stars called magnetars. And there could be hundreds of billions of galaxies in the universe.

As you might expect, galaxies are very far away from us, with the closest large galaxy - the Andromeda Galaxy - being two and a quarter million light-years away. You can see many more galaxies with binoculars or a telescope, with the majority being tens of millions of light-years away.

What Are The Different Types Of Galaxies?

There are three basic types of galaxies and, as you might expect, they each look a little different. Most people probably think of a spiral when they think of a galaxy, but not all spirals are created the same or look the same through a telescope. For example, there are barred-spirals, where the core of the galaxy has a central bar, face-on spirals, where we see the galaxy as though we were looking straight down at it, and edge-on galaxies, where we see the galaxy from the side.

From an observational or photographic point of view, spiral galaxies are the most aesthetic as the right equipment can show a lot of structure and detail. M51, the Whirlpool Galaxy, is a great example of a face-on spiral, while M31, the Andromeda Galaxy, is an easy edge-on galaxy that anyone can enjoy.

Elliptical galaxies are exactly that; they often appear oval-shaped and are usually pretty bland and featureless. They can also be faint, making them a challenge to observe, but two of the brighter examples are M32 and M110 (NGC 205), which are both satellite galaxies of the Andromeda Galaxy.

An irregular galaxy is basically one that’s neither spiral or elliptical in shape. Many of these tend to be primordial and often originate from a time before spirals and ellipticals formed, and given their distance, lie beyond the reach of many amateur telescopes. The Large and Small Magellanic Clouds, satellites of our own Milky Way galaxy, are irregular, but you’ll need to be in the southern hemisphere to see either one.


Observing Galaxies


Unfortunately, when it comes to galaxies, binoculars won’t show much, as the targets in question are too distant and faint to allow for detailed observation. Instead, the challenge - and the thrill - comes in tracking down those galaxies for yourself and understanding the immensity of what you’re looking at. As with the Andromeda Galaxy, they each contain potentially hundreds of billions of stars, trillions of planets, and countless numbers of nebulae, star clusters, black holes, and strange stars.

Telescopes, being able to gather more light, can see further and reveal more detail, but you may not see much more with a smaller scope. Mid-sized and large scopes can potentially show more detail, including the galaxy’s spiral arms and the dark dust lanes that bisect galaxies that appear edge-on to us.


Spring: The Season for Galaxies

If there’s one time of year that’s best suited to observing galaxies, it’s spring. At that time of year, the Earth is in a good position to look away from our own Milky Way galaxy, and out into the depths of space. As a result, we have the opportunity to see far distant galaxies that lie millions of light-years away.

For example, the galaxy pair of M81 (Bode’s Galaxy) and M82 (the Cigar Galaxy) can be found high in the skies to the north throughout the season. You can find them by drawing a line through Phecda and Dubhe, two of the four stars that make up the bowl of the Big Dipper, and then continuing for roughly an equal distance beyond.

Both can be detected with binoculars, but you’ll need a telescope to get the best view. You can increase the magnification to around 50x and still fit the pair within the same field of view, with M81 appearing as an oval glow with a bright core that fades off toward the edges, and M82 showing as an elongated streak, some three or four times longer than it is wide.

Using a larger aperture scope and a higher magnification can reveal more detail in both galaxies. For example, mid-sized and large scopes at 100x can show the faint spiral arms of M81 and the dark band that splits M82 in half. The galaxy will also appear to have other dark marks and texture along its entire length.

Also high in the spring sky is M51, the Whirlpool Galaxy, and despite being found within the same binocular field of view as Alkaid, the star that marks the end of the dipper’s handle, it actually lies just over the border in neighboring Canes Venatici.

A famous face-on spiral galaxy and a favorite with astrophotographers, the chances are you’ve seen images of this before. Besides the large spiral galaxy itself (NGC 5194, or M51a), there’s a smaller dwarf galaxy known as NGC 5195 (or M51b) that appears at the end of one of its arms. In reality, the two galaxies are interacting as they pass one another in space, a process that will most likely result in M51b being devoured by the larger galaxy.

Image Credit: NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)

You can see both with a small telescope, but the chances are they may only appear as two separate faint, hazy circular glows. A medium-sized scope and a magnification of around 100x will show a bright core and some texture in M51a, but the arm connecting it to M51b may remain invisible. A large scope will start to show more detail in the larger galaxy, including its spiral structure, dark dust lanes and the connecting arm to M51b.


Summer - See Our Own Galaxy Up-Close

Besides the galaxy pair of M81 and M82, there’s another bright galaxy to be found in Ursa Major that remains visible through to the start of summer. Like last season’s M51, the Whirlpool Galaxy, M101 can be found within the same binocular field of view as Alkaid, but it can be challenging unless you have dark skies. Although the galaxy is reasonably bright, its light is spread out over a relatively large area, making it a little tricky to locate. However, if the conditions are right - the skies are dark and the air is steady - it’s possible to detect the galaxy with binoculars.

Like M51, you probably won’t see much with either binoculars or a small scope, as the galaxy will most likely only appear as a faint and misty circular patch, with a slightly brighter core. A face-on spiral, mid-sized scopes and a magnification of close to 100x will start to show its structure, with two arms potentially being visible. Larger scopes can further reveal further details, including clumps of star-forming regions and texturing throughout the arms.

If you live under dark skies, away from light pollution, you can see our own galaxy, the Milky Way on almost any night of the year. However, there’s one time of year when the Milky Way is at its best, and that’s during the warm, summer months.

When we look up at the Milky Way, we’re actually looking at the galaxy from inside one of its arms. The Earth’s vantage point changes as it orbits the Sun, and during the summer months the night side of the Earth faces the center of the galaxy.

More specifically, from our point of view, the center of the galaxy appears within the boundaries of Sagittarius, a constellation best seen from around mid-July to mid-August. The brightest stars of Sagittarius form a conspicuous teapot-shaped asterism, with the heart of our galaxy appearing as steam emanating from the teapot’s spout.

This is a great area to scan with binoculars, or any telescope at low power, as you’ll see that the misty river of the Milky Way is actually made up of countless stars huddled close together. However, there’s one particular area, just a little way above the lid of the teapot, that’s particularly interesting.

M24, also known as the Sagittarius Star Cloud, is located in another arm of the galaxy, closer to the core than our own, and while it’s bright enough to be seen with the naked eye under dark skies, it’s really best seen with binoculars or a telescope.

Image Credit: Roberto Colombari

That said, it’s too large to be seen in its entirety through a telescope, even at low power, and a small scope will show a field of stars through a low magnification eyepiece, with two dark patches of dust obscuring the light of the stars that lay beyond. NGC 6603, a small, dense star cluster, can be glimpsed toward the northwestern edge. Mid-sized scopes can reveal more of the cloud, but NGC 6603 requires a high magnification to resolve its members. The view through larger scopes can be breathtaking, with numerous groups and chains of stars becoming apparent against a backdrop formed by unresolved stars of uniform brightness.


Watching the Neighbors in Autumn

Besides the Milky Way, there’s one other galaxy you can easily see with your own eyes under dark skies - M31, the Andromeda Galaxy. It appears as a tiny, elongated misty patch, and at a distance of 2.5 million light-years, it’s the most distant object visible without optical aid. Despite the mind-boggling distance (its light left the galaxy as the first humans were starting to walk the Earth) the Andromeda Galaxy is the closest major galaxy to our own.

Through a small telescope it appears as a large, elongated misty oval with a reasonably bright core. You might also see the dark dust lane that appears to slice through the galaxy in photographs and its two small satellite galaxies, M32 and M110 (aka NGC 205.)

With a mid-sized scope it’s possible to see a second, fainter dark dust lane along with some mottling and texture throughout the galaxy’s halo. A magnification of more than 100x can also start to resolve the core into individual stars, with the galaxy’s center starting to resemble a globular cluster.

Large scopes go one step further. A very high magnification of 250x or more can show bright clumps within the galaxy where stars are being born. It’s also possible to spot some of the galaxy’s attendant globular clusters, but you’ll need to know where to look for them.


There’s another neighboring galaxy we can spy upon this season, but unfortunately it’s not so easily seen as M31.

M33, the Triangulum Galaxy is roughly half a million light-years more distant than M31, but that’s not the reason why it’s harder to see. While it’s relatively bright (and, theoretically, visible to those with good eyesight and dark skies), its light is spread over an area roughly twice the size of the full Moon.

As a result, it appears fainter than it normally would, making it a little tricky to initially spot. A small telescope at low power will barely reveal it and it could disappear completely if you look directly at it. Looking at it with your peripheral (aka ‘averted’) vision will show the galaxy as being brighter at the core, but it may not be possible to see much else.

Image Credit: NASA, ESA, and M. Durbin, J. Dalcanton and B. F. Williams (University of Washington)

Unfortunately, the view doesn’t improve too much with a mid-sized scope; while the galaxy’s elongated form becomes a little more conspicuous, the increase in aperture won’t necessarily result in an increase in detail being visible. However, a large scope can start to show the ghostly spiral arms of the galaxy, with some texture near the core and faint, dark lanes of gas and dust following the curves of the arms. Look carefully and you could also see a number of individual stars, star-forming regions and a number of the galaxy’s globular clusters.


Galactic Whirlpools for Winter

After seeing two of our closest galactic neighbors in the autumn, you might be tempted to continue your adventure throughout the winter too. As we know, due to their distance and corresponding faintness, galaxies can be a little tricky to find and observe, and the galaxies of winter typically remain true to this general rule. However, one of these galaxies, M77, is at least relatively easy to find, as it’s located in the constellation Cetus, the Whale, within the same binocular field of view as Delta Ceti.

Through a small telescope at low power, you’ll notice a faint star just to the east of the galaxy, and at first glance you might think you’re looking at a double star. However, look carefully and you’ll see that one of the stars is a little hazy, and it’s this haziness that gives the galaxy away.

Increase the magnification to around 100x and the galaxy appears spherical and clearly not stellar in nature. It’s reasonably bright, with a large core that extends about halfway out to the edge of the halo.

A medium-sized scope won’t reveal much more, and while you may be able to detect some texture in the halo, you’ll need a large scope to see any hint of the arms or the galaxy’s dark lanes.

Our other winter galaxy lies in the northern constellation Camelopardalis. It’s a faint constellation that’s difficult to identify, making the galaxy NGC 2403 equally difficult to find, but on the plus side, it’s bright enough to be detected with binoculars.

Image Credit: Image Credit: NASA, ESA & A. van der Hoeven

It’s located roughly halfway between the star Muscida (Omicron Ursae Majoris) and HR 2209, a faint star on the edge of naked-eye visibility in Camelopardalis itself. The galaxy appears as an elongated haze with a slightly brighter core through a small telescope, while a mid-sized scope will show a few individual stars in the galaxy’s halo.

Large scopes can show the galaxy’s arms, with areas of star formation lending some texture to their form. There’s also the possibility of spotting the galaxy’s dark dust lanes cutting across the halo and faint stars scattered throughout.

Galaxies can be tricky to spot. However, it is absolutely worth the time and effort spent locating these targets, as they are sure to impress once you set your eyes upon them. How many galaxies have you observed?

Learn More

Interested in learning more about what's in the sky above us? Not sure where to begin? Check out our Astronomy Hub!

This Article was Last Updated on 07/26/2023