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Transcript of Galaxies
What are Galaxies?
Galaxies are huge collections of gas, stars, and dust. On average they have a several million to a trillion stars, and can be a thousand to a couple hundred thousand light years across. In the Universe, there are billions and billions of galaxies. Imagine the size of that! Like stars, they are found alone, in pairs, or in larger groups.
Elliptical galaxies are They range in shape from nearly spherical to highly flat and in size from tens of millions to over one trillion stars. Most of the stars in an elliptical galaxy are very old, and all the stars are older than an spiral galaxy's (next slide) stars.
Types of galaxies
Elliptical galaxies are a very common form of a galaxy. They were given the name because the shape is an ellipse. Usually, elliptical galaxies have much of older, low mass stars, with sparse interstellar medium and minimal star formation activity. In an average elliptical, there would be tens of millions to over a trillion stars.
like our own milky way, a Spiral galaxy is like a pinweel,( named after what it looks like) and consists of flat rotating disk. a spiral is made up gas, liquid, dust. they also have a bulge, which is a central concentration
Like the others,irregular galaxies are exactly what they sound like, because These galaxies are so uncommon, they're not part of the
. Did you know that irregular galaxies were once spiral or elliptical? but then their gravitational pull took over, and deformed them.
It is very easy to get confused between a Lenticular galaxy and an Elliptical galaxy, since they share a lot of similarities. Like, for example, the stars are very old, like an elliptical galaxy. Also, they are disks, like Spiral galaxies. The only trait that is not like any other galaxy is that they used or lost most of their interstellar matter.
Where did it come from?
The word 'galaxy' comes from the greek word "galaxias"
A lot of observations and theories suggest that the first galaxies were formed about a billion years after the big bang theory. Since then, larger and larger structures like star cluster ad superclusters have been forming. Galaxy distributions and large clusters agree with the big bang simulations of the formation, so it is helping us get closer to how the galaxies were really formed.
Edwin Hubble was an american astronomer who played a very important role in establishing the field of extragalactic astronomy.In 1925, he discovered variables which we now call Andromeda. With this, he could tell that the group of stars was way too far away to be apart of the Milky Way galaxy. Because of that proof, he proved that there were more galaxies out there.
Important to us?
Remember, We don't depend on galaxies to survive. Yes, we are in a galaxy, but we would be perfectly fine If we weren't, as long as we have the Earth and Sun. (and possibly moon.) So really, Galaxies aren't that important. As we all know, though, the universe wouldn't be a universe if there was only us, since it contains all of the galaxies. We also wouldn't be able to find out if there was someone else out there.
Galaxies and the Universe
In other galaxies, there are a lot of suns like ours. there are more solar systems. And, quite possibly, other life, even though scientist haven't found any yet. But we do have one hope. On a probe is continuing its journey, and someday, will find life on another planet in another galaxy. just to make sure, we sent a player on it, and a picture book describing how to work it. We also played all of the languages that we speak. In other galaxies, there are suns that could be a million times bigger than our own.
The Future of Galaxies
In the future, there are expectations of new generations of stars, especially in spiral galaxies, as long as they have dense molecular clouds of interstellar hydrogen in their arms. too bad for elliptical galaxies. Since they already have a lot of gas, they won't be producing anymore stars anytime soon.
Fact about the Milky Way
Ok, I don't mean to scare you or anything, but it was said that someday, in the future, our galaxy will collide with another called, "Andromeda" Andromeda is about 2.5 might years away. Compared to the universe, that's about a millimeter, maybe even smaller. But still, scientist estimated that in 4 billion years, they will start colliding, and then 2 billion years later, they will forever be joined by gravity and momentum.
Images from: www.
by Leah Walton