A galaxy is a vast collection of gas, dust, and billions of stars held together by gravity. All galaxies are made of the same things. However, they come in many different shapes and sizes.
spiral galaxies look like giant pinwheels. The whirlpool’s arms are made of stars and lots of gas and dust. Gas and dust are just some of the main ingredients needed to form new stars. Young stars burn much brighter than older ones, which is why spiral galaxies are often among the brightest in the universe. About 60% of nearby galaxies are spiral galaxies. Our own galaxy, the Milky Way, is a prime example.
Elliptical galaxies are shaped like extended circles or ellipses. Some elliptical galaxies are larger than others. One of them may look almost perfectly round. Another may look long and flat. Elliptical galaxies mostly contain older stars. This means they are often not as bright as spiral galaxies.In addition, they contain very little dust and gas. Elliptical galaxies are the largest and most commonly observed galaxies. They make up about 20% of nearby galaxies.
Irregular galaxies are just that: irregular. They have no common form.Irregular galaxies are among the smallest galaxies observed by scientists. However, they can also be very shiny. Like spiral galaxies, irregular galaxies are often filled with gas, dust, and many bright young stars. About 20% of nearby galaxies are irregular galaxies.
Quasars are compact regions at the center of a galaxy.They give off large amounts of energy. In fact, quasars are among the brightest objects in the universe. There are no quasars near our Milky Way.
