I'm going to throw something at you. Ready? Oh, you want to know what it is first? I guess that will make easier to catch. Is it a frisbee that's light and round? Is it a football, which is bigger and shaped like a nut? Or is it a beach ball that isn't filled enough, so it's light and squishy? It's good to know what is being thrown at you so you know how it will act while it's in the air. Things are no different in space. There are lots of groups of stars out there and they come in all kinds of different shapes and sizes.
You live on a street. This street is one of many streets that make a city. This city is one of many cities that make a state. Those states make a country. Those countries make a world. Those worlds make a solar system, with a star, our sun sitting in the very middle. So what do a lot of stars make? A galaxy
is a huge collection of stars, dust, and planets that are held together by gravity. There are even a lot of galaxies and, like the things you throw, there are all different kinds.
Galaxies are not shaped like suns or planets. They are more like things you throw, maybe because they are spinning through space. Instead of being all together, they look like a lot of floating lights in space that make up a kind of shape. A spiral galaxy
is flat, with a lot of stuff in the middle and many arms spinning around it. Think of a pinwheel made of lights. Or better yet, think of an octopus with a big head in the middle and many arms sticking out its sides that spin as you spin its head. You live in a spiral galaxy, right on one of the octopus arms.
A galaxy gone spiral.
Now that you know your space address, we can go out and find other kinds of galaxies. Look ahead! What is that spinning toward us? Is it a football? An elliptical galaxy
is the biggest kind of galaxy. They come in many different shapes from a circle to a football. This means they have a lot of stuff in their middle and not so much in their pointed ends. Some of these galaxies are smaller than ours, but others can be up to twenty times bigger. Those are not footballs we want to try and catch.
Galaxy football anyone?
Look at those stars! What shape is that? It's, sort of a . . . That looks like a . . . Hmm. Have you ever tried to catch a ball that sort of wobbled out of its path through the air? When you get your hands on it, you can see that it is not very round. Irregular galaxies
do not have a shape like a circle or football. They look like dust in the wind, or like someone spilled stars into a part of space. Maybe they are trying to make something but they just do not know what yet. Scientists believe that these galaxies might be the building blocks for other galaxies. They do not look easy to catch.
This galaxy looks like it needs to shape up.
Balls come in all kinds of shapes and sizes. Galaxies do too. Some spin through space like a frisbee . . . or an octopus. Some are like footballs and are way too big to catch. Some are like those squished balls that do not stay on path. Lucky for you, you do not ever have to catch any of these. Oh, what was I going to throw? I already threw it: a lot of words about galaxies. Did you catch them all?References:
Synonym. "Three Main Types of Galaxies" Synonym, 2011. <http://classroom.synonym.com/three-main-types-galaxies-2474.html
Astro.com. "Types and Classification of Galaxies" Cornell, 2010. <http://www.astro.cornell.edu/academics/courses/astro201/galaxies/types.htm
Kids Astronomy. "Learn About Galaxies" Kids Astronomy, 2012. <http://www.kidsastronomy.com/galaxys.htm