Question

20)the sun is inferred to be the most luminous when it is classified as a (1) giant star (2) gas cloud (nebula) (3) white dwarf star (4) main - sequence star 21) base your answer to the following question on the diagram below and on your knowledge of earth science. the diagram represents the expansion of a portion of the universe from its origin until the present. the timeline represents billions of years. letter x indicates two celestial objects. present timeline (billion years ago) 15 origin of universe two pieces of evidence that support the theory that the universe is expanding are the (1) blue shift of light from distant stars and the existence of nuclear fusion (2) red shift of light from distant stars and the existence of nuclear fusion (3) red shift of light from distant stars and the existence of cosmic background radiation (4) blue shift of light from distant stars and the existence of cosmic background radiation 22) a red shift in the light from very distant galaxies suggests that the universe is (1) moving randomly (2) contracting (3) fixed and stationary (4) expanding 23) the suns position in space is best described as the approximate center of (1) a constellation (2) the milky way galaxy (3) our solar system (4) the universe

Explanation:

• Question 20: The Sun is a main - sequence star. Main - sequence stars are in a stable state of hydrogen fusion and are common and well - studied.
• Question 21: The red shift of light from distant stars shows that they are moving away from us, indicating the expansion of the universe, and cosmic background radiation is a remnant of the early universe, supporting the Big Bang theory and the expansion of the universe.
• Question 22: A red shift in the light from distant galaxies means the galaxies are moving away from us, which is evidence that the universe is expanding.
• Question 23: The Sun is at the approximate center of our solar system. It is the gravitational center around which the planets, asteroids, and other objects in the solar system orbit.

Answer:

1. (4) main sequence star
2. (2) red shift of light from distant stars and the existence of cosmic background radiation
3. (4) expanding
4. (3) our solar system