?2.5.2 Test (CST): Where Is Earth? Question 4 of 15 2 Points Match each galaxy to its description. spiral galaxy irregular galaxy elliptical galaxy ? ? ? the Milky Way is one contains mostly older stars contains mostly young stars SUBMIT
The Correct Answer and Explanation is:
Correct Matches:
- Spiral galaxy → The Milky Way is one
- Elliptical galaxy → Contains mostly older stars
- Irregular galaxy → Contains mostly young stars
Explanation
Galaxies are large systems of stars, gas, dust, and dark matter held together by gravity. They come in three main types: spiral, elliptical, and irregular, each with distinct characteristics.
- Spiral Galaxy:
Spiral galaxies have a flat, rotating disk with arms that spiral outward. They typically have a central bulge filled with older stars and spiral arms containing younger stars and star-forming regions. The Milky Way, our home galaxy, is a classic example of a spiral galaxy. These galaxies are rich in gas and dust, which fuel the birth of new stars. Spiral galaxies are among the most common types observed in the universe. - Elliptical Galaxy:
Elliptical galaxies are round or oval in shape and lack the flat disk and arms of spiral galaxies. They mostly consist of older stars and have very little gas and dust. Because of this, they have little to no ongoing star formation. Elliptical galaxies vary in size and are often found in galaxy clusters. Their smooth appearance and reddish color come from the aging stars that dominate them. - Irregular Galaxy:
Irregular galaxies have no defined shape or structure. They often look chaotic and are usually smaller than spiral or elliptical galaxies. These galaxies tend to contain younger stars, and they are rich in gas and dust, which supports active star formation. Irregular galaxies are often formed through gravitational interactions or collisions with other galaxies. The Large and Small Magellanic Clouds near the Milky Way are examples.
By understanding these galaxy types, astronomers can study how galaxies evolve and what conditions are necessary for star formation. The classification also helps us understand where our own solar system fits into the larger structure of the universe.
