Your Night Sky for Sept. 4, 2019

There’s been a lot of varied information about the Andromeda Galaxy. Because it’s 2.5 trillion LY from us, it only appears to be a fuzzy blob. Although it was seen for a long time, people thought it was a giant nebula. It was called the “Little Cloud”, which is basically what it looks like with unaided vision.

In 1925 Edwin Hubble examined it and determined that it was another galaxy. He identified Cepheid variable stars for the first time on astronomical photos of Andromeda. To do that he used a 2.5 meter Hooker Telescope. Then in 1943 Walter Baade was the first person to resolve stars in the central region of the galaxy.

Opinions vary as to whether it’s larger than the Milky Way. Some people think it’s 150,000 LY across and the Milky Way is 100,000 LY across. Since it’s so far away, the light we see is 2.5 trillion years old, so we really don’t know what it looks like now. When the light we see left Andromeda there was only basic life here on Earth.

The latest theory is that it’s older than and not as active as the Milky Way. So it’s not producing as many stars as it used to. There may only be one per year as opposed the Milky Way producing three to five per year. Currently is has approximately one trillion stars, which is twice the amount of the Milky Way.

It is moving closer to us at 68 miles per second, and our galaxies will merge in three to four billion years. Then we will combine to form a giant galaxy. Like the Milky Way it’s a barred spiral galaxy.
Andromeda is the farthest object we can see with the naked eye. It’s also the largest galaxy in our local group of 30. Its elongated stream of gray green stretches the diameter of two full moons, but only the bright central area is visible to the naked eye. With a telescope it becomes the width of six full moons. Even then it appears to be a thin oval shape fuzzy patch of light with a bright central core. A large telescope is required to really examine it.

To find Andromeda, look in the northeast for the constellation Cassiopeia with the W on its side and the bottom of the W pointing down slightly to the East. Search to the right and down a little until you see the fuzzy blob. Now you’ve found it!  Try binoculars or a telescope for a little more detail.

It has eight satellite galaxies with four visible with a telescope. Its name comes from the Andromeda constellation that it sits above which is the left streamer of the Great Square of Pegasus constellation.

It’s visible on a clear moonless night late summer into early spring. As autumn progresses Andromeda will raise high in the sky. So go out and look for it when the sky is dark and clear, and say hi to whatever beings live there.


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