Quiz 1 Answers

1. What is our place in the universe?
2. How did we come to be?
3. How can we know what the universe was like in the past?
4. Can we see the entire universe?
5. How big is Earth compared to our solar system?
6. How far away are the stars?
7. How big is the Milky Way Galaxy?
8. How big is the universe?
9. How do our lifetimes compare to the age of the universe?
10. How is Earth moving in our solar system?

1.Earth is part of the solar system, which is in the Milky Way Galaxy, which is a member of the Local Group of galaxies in the Local Supercluster

2. --The matter in our bodies came from the Big Bang, which produced hydrogen and helium.

   -- All other elements were constructed from H and He in stars and  then recycled into new star systems, including our solar system.

3. When we look to great distances, we are seeing events that happened long ago because light travels at a finite speed.

4. No. The observable portion of the universe is about 14 billion light-years in radius because the universe is about 14 billion years old.

5. On a scale of 1-to-10 billion, the Sun is about the size of a grapefruit. The Earth is the size of a tip of a ballpoint pen about 15 m away. The distances between planets are huge compared to their size.

6. On the same scale, the stars are thousands of kilometers away.

7. It would take more than 3000 years to count the stars in the Milky Way Galaxy at a rate of one per second. The Milky Way Galaxy is about 100,000 light-years across.

8. -- 100 billion galaxies in the observable universe 

    -- 14 billion light-years in radius

    -- As many stars as grains of sand on Earth's beaches

9. On a cosmic calendar that compresses the history of the universe into 1 year, human civilization is just a few seconds old, and a human lifetime is a fraction of a second.

10. It rotates on its axis once a day and orbits the Sun at a distance of 1 AU = 150 million km.