Astronomy 101:Galaxies

Today, we are gonna start to talk about the big scale of astronomy, galaxies

The whole time today, I will be talking about galaxies. They are the biggest building blocks for stars to form.

• There are many types of galaxies, and astronomers recognize only a couple, like spiral, barred spiral, lenticular, elliptical, irregular, and peculiar
• Even though the Milky Way seems to be average, most galaxies are way smaller than the Milky Way. Some of these include the Large Magellanic Cloud and the Small Magellanic Cloud. We classify those types of galaxies as dwarf galaxies
• Like the Sun and Earth or Earth and the Moon, major galaxies usually have smaller galaxies orbiting them. I have already mentioned the Large and Small Magallanic clouds, which orbit us.
• According to physics, without any extra forces, all galaxies would fly apart because their rotation would push stars away from the center. But galaxies are not flying apart because of dark matter
• Galaxies collide all the time. You may have heard that the Andromeda galaxy will collide with us, but did you know that the Magallenic clouds are too?
• Galaxies are very old, take our Milky Way for example: it is 13.6 billion years old! That is about as old as our universe
• Galaxies are mostly space; they are full of emptiness, and that's why our nearest star is light-years away
• Our galaxy is flatter than a 12-inch pizza
• The smallest known galaxy has fewer stars than some galaxy clusters
• Some galaxies are very active: they are called quasars, they have a huge black hole in the middle of it and it is swallowing the galaxy fast
• Spiral galaxies can “transform” into elliptical galaxies, given that some collisions have happened in their lifetime
• Given that another universe was made using completely different conditions, galaxies can be shaped in unimaginable ways
• Depending on the galaxy type, stars can be all over the place and have insanely weird orbits or just be straight and have normal orbits.
• Stars in galaxies can also vary in size; for example, young galaxies have a lot of gas that stars can use to form. So stars are born bigger. Old galaxies have barely enough gas to form stars, so stars are usually smaller.