Directions: Fill out the INSIDE of the foldable first using the reading and pictures below. For the bottom of the foldable write at least 4 things that the galaxy looks like. Once the inside of your foldable is filled in close the foldable and draw a picture of each galaxy on the front.
Galaxies
If you look out on a clear night far from city lights, you can see hundreds of stars. Many of these stars are part of our galaxy, which is called the Milky Way. Our galaxy actually contains many more stars than you can see.
A galaxy is a large group of gas, dust, and millions of stars. The biggest galaxies contain more than a trillion stars. Scientists can’t actually count the stars, of course. They estimate how many stars are in a galaxy by measuring the size and brightness of the galaxy. The bigger and brighter the galaxy, the more stars it has.
Galaxies come in different shapes and sizes. Scientists classify galaxies by shape. The three most common types of galaxies are spiral, elliptical, and irregular.
A galaxy is a large group of gas, dust, and millions of stars. The biggest galaxies contain more than a trillion stars. Scientists can’t actually count the stars, of course. They estimate how many stars are in a galaxy by measuring the size and brightness of the galaxy. The bigger and brighter the galaxy, the more stars it has.
Galaxies come in different shapes and sizes. Scientists classify galaxies by shape. The three most common types of galaxies are spiral, elliptical, and irregular.
Spiral Galaxies
A spiral galaxy is shaped like a flattened disk. They have two parts, a central bulge and arms that form a spiral around the center. The bulge is a dense group of old stars. The arms are made of gas, dust, and much younger stars. The Milky Way is a spiral galaxy. We live in the Milky Way. Our sun is one of the 200 billion stars in the Milky Way. From Earth, the edge of the Milky Way looks like a bright belt of stars that stretches across the night sky. |
Elliptical Galaxies
About 1/3 of all galaxies are simply massive blobs of stars. An elliptical galaxy is made of many stars and looks like a snowball. They usually have very bright centers. Elliptical galaxies vary widely in size. Both the largest and the smallest known galaxies are elliptical. Very large elliptical galaxies can reach 300 million light years in diameter and can contain as many as 5 trillion stars! Dwarf ellipticals, which are very common, may contain only 1/100,000th as many stars as the Milky Way! There is very little free gas in an elliptical galaxy. In fact, elliptical galaxies contain primarily old, red stars.Therefore, few new stars form there. Some of these galaxies form when two or more spiral galaxies collide |
Irregular Galaxies
Irregular galaxies are galaxies that don’t fit into any other class. An irregular galaxy has no clear shape. It may have as few as 10 million or as many as several billion stars. Many of these galaxies are close companions of large spiral galaxies. Many form from the gravitational pull of these neighboring galaxies. |
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