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Naked-Eye Observing - Star Clusters, Nebula, and a Galaxy

There are three types of star clusters: open, globular, and apparent.

Globular clusters contain tens of thousands of stars and generally exist surrounding the core of our galaxy - this area is called the Halo, and is typical of spiral galaxies. This makes them hard to see without a telescope.

Open clusters exist within our galaxy and can sometimes be viewable without a telescope or binoculars. Here are some examples:

The Pleiades, an open cluster on the right, looks like a mini-little dipper. On the left is Taurus, the center of which looks like an open cluster. This is an asterism called Hyades. This can also be called an 'apparent' cluster.

The Perseus double-cluster is a bit smaller and harder to see than the above open clusters, but worth looking for.

The third type of cluster is not really a physical cluster, it just looks like one from Earth. An example is Hyades within the constellation Taurus - see the first image above. These types of "clusters" can be very dramatic as they can contain stars of various colors (it is common for stars of a real cluster to sometimes be identical in color, like the Pleiades).

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M42 - The Orion Nebula:

The constellation Orion is probably the most recognized constellation in the night sky. It covers a pretty large area, and has stars of a variety of sizes and colors. An example is Betelgeuse, the bright red star on the upper left of the constellation - bottom right for those in the southern hemisphere.

There are three bright stars that make up the belt, and some bright stars almost perpendicular to the belt - the sword.

Can you see the "cloudy" star within the sword of Orion? If you do, you are looking at M42 - the Great Nebula in Orion.

The image above is from Starry Night, planetarium software, but shows Orion as one would see from dark skies. Can you see the nebula? I will leave you with the challenge.

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M31 - The Andromeda Galaxy:

The Andromeda Galaxy (M31) is the closest large galaxy to the Milky Way. It is also the only galaxy (not including the Large and Small Magellanic clouds) that can be seen with the eye.

It is 2.2 million light years away - so it takes light 2.2 million years to reach Earth. Even though it is so far, it still covers an area of sky greater than a full Moon!

The Andromeda Galaxy is in the constellation Andromeda. It can be hard to see in this Starry Night image, but this is how it can be seen from dark skies. Just look for the cloudy oval.

As with the Orion nebula, I will not give away the location of M31. If you can see it here, you will be able to see it for real from a dark sky location.

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