1. Scales of the Universe

2. The Earth is 12,700 km in diameter. The Sun is 1.39 million km in diameter.

3. Imagine the Sun is the size of the classroom. How large would the Earth be?

4. The size of a grapefruit (9.2 cm diameter) or small globe

5. Now imagine that the Solar System (to the boundary of the solar winds) is the size of the classroom. (200 AU diameter)

6. 1 Astronomical Unit = 149,597,870,700 m or, roughly the distance between the Earth and the sun. http://www.youtube.com/watch?v=sBap15NWmsI

7. How large would the sun be? How large would the earth’s orbit around the sun be? How large would the earth be?

8. Sun: a grain of salt (0.46 mm diameter) about the diameter of the tip of a toothpick Orbit: a CD or half a roll of masking tape (10 cm diameter) Earth: microscopic bacteria (4 micrometers – 4 millionths of a meter)

9. Now imagine the solar neighborhood (the closest stars to the sun; 65 light-years diameter) were the size of the classroom. How big would the solar system be?

10. A light-year is a measure of distance, not time. 9.4605284 × 10 15 meters The distance light travels in a year.

11. A grain of salt (0.49 mm diameter) about the diameter of the tip of a toothpick

12. Now imagine the Milky Way (160,000 light-years) is the size of the classroom. How big would the solar neighborhood be?

13. The Milky Way is our galaxy, made up of over 100 billion stars.

14. A peppercorn (4mm diameter) about the size of a piece of gravel

15. Our Local Group of Galaxies is made up of 3 spiral galaxies (Milky Way, Andromeda – M31, and Triangulum - M33), plus several dwarf galaxies

16. Now imagine the Local Group of Galaxies (6.5 million light- years across) is the size of the classroom. How big is the Milky Way?

17. The size of a large pizza (50 cm in diameter)

18. A Supercluster is a cluster of clusters. The Virgo Supercluster contains over 1000 galaxies.

19. Imagine the Local Supercluster of Galaxies (130 million light- years) is the size of the classroom. How large is the Local Group? How large is the Milky Way?

20. Local Group: A basketball or globe(25 cm in diameter) Milky Way: A button (1.25 cm in diameter) about the diameter of a large thumbtack

21. It is believed that there are over 100 billion galaxies. The Observable Universe is 156 billion light- years in diameter.

22. Imagine the entire observable universe were the size of the classroom. How large would the Local Supercluster be? How large would the Local Group be?

23. Local Supercluster: A small button (8.3 mm diameter) about the diameter of a large thumbtack Local Group: A small grain of salt (0.2mm diameter)