1. What is your “cosmic” address? Where do you live? Your home or your school has an address: a street, a city or town, and a country. When someone sends you a letter, they write your address, so that your mail carrier knows the letter should go to you. For example, the address of Brookside School is: 100 Brookside Ave. Allendale, NJ 07401 What is your address? Does this address really describe where you are? Imagine extending the address out to bigger and bigger divisions, until it becomes a "cosmic address" that includes your continent, planet, galaxy, and universe. Try writing yours!

2. Brookside School’s Cosmic Address: 100 Brookside Ave. Allendale, NJ 07401 United States of America North America Earth The Solar System Orion Arm The Milky Way Galaxy Local Group of Galaxies Local Supercluster of Galaxies (aka Virgo Supercluster) The Universe How did you do?

3. The last step of the cosmic address is the largest division: the Universe. The universe is actually everything and everywhere. Every star and every galaxy we see is part of the same universe. The universe is a really big place! How big is the universe?

4. Allendale is just over 8 square kilometers (about 3 square miles)

5. New Jersey is about 743 km long.

6. It’s about 4,764 km from New York to San Francisco

7. Earth’s diameter is about 12, 742 km

8. The sun is about 150,000,000 km from Earth. Now distances are so big that kilometers are not that useful.

9. The solar system is thought to be about 200,000 AUs in diameter.

10. Beyond our solar system, distances are so great that AUs are not that useful. 1 light year is approximately 9.5 trillion kilometers.

11. For measuring between stars and galaxies, we use light years:

12. Astronomers often use an even BIGGER distance: the parsec 1 parsec (pc) = 3.26 lightyears (ly) (One parsec is the distance corresponding to a parallax of one arc second.) one arc second = 1/3600 degrees of a circle

14. Time out: What is Parallax?

15. Figure it out: Does parallax increase or decrease with distance?

16. Back to the size of the Universe: The Local Group is about 10 million light years across.

17. The Virgo Supercluster is about 200 million light years across!

18. The entire Universe is thought to be 160 BILLION light years across! (but we don’t really know….) (The observable universe is about 93 billion light years across.) scaleofuniverse.com

19. Check out this website: Scaleofuniverse.com

20. Distances in Space 3/18/13 How do we measure distances in space? Astronomical Unit (AU) Light year Space is so VAST, that we need to use special units. The average distance between the earth and the sun = 149.6 million kilometers (150 million km) Used to measure distances within our solar system (or within another star system) The distance light travels in one year = 9.5 trillion kilometers Used to measure distances beyond our solar system