Quiz 1: Jessica Horn

Quiz

1. What is our place in the universe? Earth is a planet orbiting the Sun. Our Sun is one of more than 100 billion stars in the Milky Way Galaxy. Our galaxy is one of about 40 galaxies in the Local Group. The Local Group is one small part of the Local Supercluster, which is one small part of the universe.
2. How did we come to be? The universe began in the Big Bang and has been expanding ever since, except in localized regions where gravity has caused matter to collapse into galaxies and stars. The Big Bang essentially produced only two chemical elements: hydrogen and helium. The rest have been produced by stars, which is why we are composed of star stuff/dust. 
3. How can we know what the universe was like in the past? Light takes time to travel through space, so the farther away we look in distance, the further back we look in time. When we look billions of light- years away, we see pieces of the universe as they were billions of years ago.
4. Can we see the entire universe? No, the age of the universe limits the extent of our observable universe. Because the Earth is about 14 billion years old, we'd be trying to look to a time before the universe existed because our observable universe extends to a distance of about 14 billion light-years.
5. How big is Earth compared to our solar system? On a scale of 1 to 10 billion, the Sun is about the size of a grapefruit. Planets are much smaller, with Earth the size of a ballpoint pen.
6. How far away are the stars? On the 1-to-10 billion scale, it is possible to walk from the Sun to Pluto in just a few minutes. On the same scale, the nearest stars besides the Sun are thousands of kilometers away.
7. How big is the Milky Way Galaxy? Using a scale in which the Milky Way galaxy is the size of a football field, the distance to the nearest star would be only about 4 millimeters. There are so many stars in our galaxy that it would take thousands of years to count them all.
8. How big is the universe? The observable universe contains roughly 100 billion galaxies, and the total number of stars is comparable to the number of grains of dry sand on all the beaches on Earth.
9. How do our lifetimes compare to the age of the universe? On a cosmic calendar that compresses the history of the universe into one year, human civilization is just a few seconds old, and a human lifetime lasts only a fraction of a second. 
10. How is Earth moving in our solar system? Earth rotates on its axis once each day and orbits the Sun once each year.Earth orbits at an average distance from the sun of 1 AU and with an axis tilt of 23 and a half degrees to a line perpendicular to the ecliptic plane. 

Sources: Class Notes, Textbook