Until 1924 everybody believed that the Milky Way galaxy, a swirling collection of stars a few hundred thousand light-years across, made up the entire universe.
That was until Edwin Hubble spotted a Cepheid variable star in the Andromeda Nebula, and using different techniques showed that the nebula was nearly a million light-years away, far beyond the bounds of the Milky Way. Before this astronomers thought that galaxies (or "spiral nebulae") are just clouds of interstellar gas, inside our own Milky Way galaxy.
These days any amateur astronomer using a small telescope can see hundreds of galaxies, millions of light-years away. Mainly there are three types of galaxies you can observe:
• Spiral galaxies like our own are the most common type, they are made of spiraling arms of stars and dust coming from a central core. Seen through the telescope they appear like small round or slightly elongated patches of light, when we see them face on. If the galaxy is seen from the edge it will have a very elongated, spindle-like shape.
• The second type of galaxy is called elliptical. Seen through the telescope they are usually circular, or ovals that are near circular in shape. Most of the galaxies belonging to this type are bright, but they lack any observable details.
• Irregular galaxies have no definite shape, being formed of chaotic agglomerations of stars and gas. One example of an irregular galaxy is Messier's catalog M82, in Ursa Major.
Galaxies observed with a 150-mm telescope
Galaxy M106. Bernie and
Jay Slotnick/Adam Block/
M106 is a bright galaxy in Canes Venatici. It is large and elongated, near the faint nucleus I've seen a 10th magnitude star.
NGC 4036 is a 11.6 magnitude galaxy in Ursa Major. In the eyepiece it appears small and elongated with a very bright nucleus.
13th-magnitude NGC 5198 is located only a few arcminutes from M51, the great galaxy in Canes Venatici. It is easily seen in the eyepiece, it has a stellar nucleus.
is a 12.2 magnitude galaxy in Bootes. It is pretty large, with a bright nucleus. This galaxy shares the same field with NGC 5529
, a faint galaxy glowing at magnitude 12.7. NGC 5529 is barely visible at 70x, on the charts it appears very elongated but seen through the eyepiece it is round and very small.
NGC 5350, NGC 5354 and NGC 5353
in Canes Venatici form an interesting group, three 12.5 magnitude galaxies clustered in a space of five arcminutes. NGC 3550 is the largest of the group, diffuse, without condensation towards the nucleus. NGC 5354 and NGC 5353 are much smaller and very close one to another. Both have stellar nuclei.
is a 12.3 magnitude galaxy in Hydra, located 25 arcminutes west of 26 Hydrae. It has a round shape and small size, with a diffuse but evident nucleus.
Separated by only 25 arcminutes from the famous globular cluster M13, you will find NGC 6207
, a 12.2 magnitude galaxy. It has an elliptic shape, with condensation towards the bright nucleus.
is a bright galaxy in Ursa Major. It is large, round shape, with a bright center.
In the vicinity of Cor Caroli you will find NGC 4914 and NGC 4868. NGC 4914
is 12th magnitude, small size, round, with an easily seen diffuse nucleus.
13th magnitude NGC 4868
it's difficult to observe, but the nucleus is fairly evident.
is small and faint. I've observed a dim star very close to the galaxy.
is a lot larger then NGC 7742. It is round, without an evident nucleus.
is a small, faint galaxy in Pegasus. It is elongated and has a stellar nucleus.
is fairly big, its shape is difficult to observe, and using averted vision it seems elliptical. Seen directly it seems round. It is diffuse towards the edges and has a stellar nucleus. To the west, near the galaxy, you will find a bright star.
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