Question

1. why do the patterns of the stars appear to shift westward slightly from night to night?
2. list the three basic types of galaxies.
3. what type of galaxy is the milky way galaxy?
4. describe a quasar.
5. imagine that astronomers found a galaxy that was 20 billion light - years from the earth. how would they have to revise the big bang theory to account for such a discovery?

Explanation:

1. The Earth's orbit around the Sun causes the stars' apparent west - ward shift from night to night as the Earth moves in its orbit and our vantage point changes.
2. The three basic types of galaxies are elliptical, spiral, and irregular. This classification is based on their shape and structure.
3. The Milky Way Galaxy is a spiral galaxy, characterized by its spiral arms and a central bulge.
4. A quasar is a highly luminous and distant active galactic nucleus, powered by a super - massive black hole at its center.
5. The current estimate of the age of the universe is about 13.8 billion years. If a galaxy 20 billion light - years away were found, it would suggest that either the universe is older than currently thought, or that there are aspects of the expansion of the universe (such as faster - than - light expansion in the early universe) that need to be re - evaluated and incorporated into the big bang theory.

Answer:

1. Due to the Earth's orbit around the Sun changing the vantage point.
2. Elliptical, Spiral, Irregular.
3. Spiral.
4. A highly luminous and distant active galactic nucleus powered by a super - massive black hole.
5. Either the universe is older or aspects of its expansion need re - evaluation.