PHYS 20 - Homework 1
Moons are satellites that orbit stars.
Which of the following correctly lists our “cosmic address” from small to large?
(A)Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster,
(B) Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, uni-
(C)Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, uni-
(D)Earth, Local Group, Milky Way Galaxy, solar system, Local Supercluster, uni-
When we say the universe is expanding, we mean that:
(A) Everything in the universe is growing in size.
(B)The average distance between galaxies is growing with time.
(C)The universe is getting older.
(D)Our knowledge of the universe is growing.
Could we see a galaxy that is 20 billion light-years away?
(A) Yes, if we had a big enough telescope.
(B)No, because it would be beyond the bounds of our observable universe.
(C)No, because a galaxy could not possibly be that far away.
The star Betelgeuse is about 425 light-years away. If it explodes tonight:
(A) We’ll know because it will be brighter than the full Moon in the sky.
(B) We’ll know because debris from the explosion will rain down on us from space.
(C)We won’t know about it until 425 years from now.
(D)We won't know until about 4 hours after the explosion.
The fact that nearly all galaxies are moving away from us, with more distant ones
moving faster, helped us to conclude that:
(A)The universe is expanding.
(B) Galaxies repel each other like magnets.
(C)Our galaxy lies near the center of the universe.
(D)The universe is contracting.
How fast does light travel?
(A) 200,000 Km/s
(B) 160,000 Km/s
What is the approximate age of our solar system?
(A)4 billion years
(B) 12 billion years
(C)3 million years
(D)1 billion years
What is a light-year?
(A)The distance light travels in one year.
(B) The time it takes for the light to get to us from a distant object.