1. The Solar System & Beyond Chapter 21

2. The Sun The closest star Center of our universe Made up of hydrogen and helium atoms that produce light and heat through nuclear fusion

3. Measuring Space Distance Light Year – the distance that light travels in one year –One light year is about 9.46trillion kilometers –Light travels at 300,000 km/s –The farthest objects we can observe are more than 10 billion light years away Astronomical Units measure distance between the earth and a star

4. Expanding Universe Astronomical Units (AU) are a unit of measurement used to calculate the distance between the Earth and the sun as well as other stars Earth is 1 AU from the sun and Mars is 1.54 AU from the sun

5. Mercury The closest terrestrial planet to the sun Has a diameter of 4,879 km Its revolution around the sun takes 88 days 3.2 light minutes from the sun Temperature range -127ºC to 427ºC

6. Venus 2 nd terrestrial planet from the sun Spins clockwise on its axis (retrograde) Has the densest atmosphere 6.0 light minutes from the sun One year revolution is 224 days long Temperature 464 C

7. Earth 3 rd Terrestrial Planet From the Sun Only one that supports life 8.3 light minutes from the sun 12,756 km wide Revolution 365 days

8. Mars 4 th planet from the sun 6,794 km in diameter Nicknamed the red planet Temperatures range from -123 C to 37 C 12.7 light minutes from the sun

9. Jupiter Largest gas giant Diameter: 142,984 km Revolution 11 ¾ Earth years Temperature -110 C Radiates more energy than it receives. Distance from sun 43.3 light minutes

10. Saturn Winds blow at 1000 mph at its equator Width is 120,536 km in diameter Revolution 29 Earth years and 155 days Temperature -140 C Has Icy rings Light from the sun reaches here in 1.3 light hours

11. Uranus Spins on its side, its poles, possibly due to planet collision Diameter 51,118 km Temperature -195º C One revolution is 83 Earth years and 273 days 2.7 light hours from the sun

12. Neptune Has belts of visible clouds Diameter 49,528km 4.2 light hours from the sun Has thermal energy center that warms the planet like Jupiter and Neptune Revolution 163 Earth years Temperature -200 C

13. Pluto ????? Farthest from the sun, Bizarre Orbit Demoted from planet August 2006 Diameter 2,390 km Temperature -225 C Revolution every 248 Earth Years 5.4 light hours from the sun