Galaxies are generally classified into three main types: spiral galaxies, elliptical galaxies, and irregular galaxies.
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Spiral Galaxies: These galaxies are characterized by their flat, rotating disks containing stars, gas, and dust, as well as a central concentration of stars known as the bulge. They often have beautiful spiral arms that extend outward from the center. The Milky Way is a spiral galaxy, exemplifying features such as a defined structure and ongoing star formation in its arms.
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Elliptical Galaxies: Elliptical galaxies range from nearly spherical to elongated shapes and contain older stars with little to no new star formation. They are generally composed of older, cooler stars and have very little gas and dust, resulting in a smooth, featureless appearance. Their structures are defined by their elliptical shapes, hence the name.
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Irregular Galaxies: Irregular galaxies do not have a distinct shape like spiral or elliptical galaxies. They often contain a mix of young and old stars and have significant amounts of gas and dust. Their irregular shape is typically the result of gravitational interactions with other galaxies or mergers.
The galaxy that Earth is part of is called the Milky Way, and it is classified as a spiral galaxy.