The Solar System:

1. The Solar System: A4: Our Solar System The sun and inner planets

2. Our Solar System • Solar System – a collection of planets, asteroids, moons, and other matter that occupy the space around a sun and are held within its gravitational pull • Our solar system is located in the MilkyWay galaxy • Milky Way is a spiral galaxy with arms and a central bulge • Our solar system is located in one of the arms

3. Our Sun • Our Sun – Has 3 interior layers & 3 atmosphere layers • Interior Layers • Core – produces enormous amounts of energy through nuclearfusion • During the fusion process, hydrogen atoms join together to form helium • Requires temperature of about 15 million oC

4. Our Sun • Radiation Zone – region of tightly packed gas where energy is transferred in the form of electromagneticradiation • It is the middlelayer of the sun • Because it is sodense, energy can take over 100,000 years to move through it

5. Our Sun • Convection Zone – hot gases rise to the surface, then sink back down as they cool, forming loops • It is the outerlayer of the sun • The loops allow energy to move through the layer

6. Our Sun • Atmosphere Layers • Photosphere – visible layer (surface) that gives off light • Chromosphere– Very thinmiddle layer that produces • the yellow color that we see • Corona – the halo that surrounds the sun and extends for millions of kilometers • Gradually thins to streams of electrically charges particles called the solarwind

7. The Planets • The Planets – Earth is just one of ________ planets that orbit the sun. • nine? • eight Mercury, • How many planets are there? Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto? • Is Pluto a planet? No • Definition of a Planet • 1. It is in orbit around the sun • 2. It is nearly round in shape • 3. It has cleared the neighborhood in it’s orbit

8. The Planets • To remember the order of the planets, just remember the saying: MyVeryExcellentMotherJustServedUsNachos • The eight planets of our solar system are: • Mercury, • Venus, • Earth, • Mars, • Jupiter, • Saturn, • Uranus, • and Neptune • Theyare divided into two groups of four: the inner planets and the outer planets

9. The Inner Planets • The four inner planets are small, dense, and have solid rocky surfaces. • Mercury – smallest planet (about the size of our moon) and closest to the sun • Rotates around the sun in 88 days • Mostly made of dense metal iron with large plains and craters • Very littlegravity because of its small mass • Virtually noatmosphere • Temperatures – as hot as 430o C during the day and -170o C at night

10. The Inner Planets • Venus – has a similar size, mass, and internal structure to Earth • Rotates around the sun in 7.5 months, but takes 8 months to rotate on its axis. So 1 day is longer than 1 year • Rotates from east to west which is opposite to most planets. • Astronomers believe it was struck by a large object that caused it to change its direction of rotation

11. The Inner Planets • Atmosphere is mostly carbondioxide with thick clouds of sulfuric acid. • The carbon dioxide and clouds create a greenhouseeffect trapping heat • Has the hottest surface temperature of all the planets at 460o C (hot enough to melt lead) • Mercury & Venus

12. The Inner Planets • Earth – Only planet in our solar system able to support livingorganisms • Rotates around the sun in 365.25 days, and takes 24 hours to rotate on its axis. • Has 3 main layers:core, mantle, and crust • Crust is a solid, rocky surface • Water – it is the only planet with liquid water • 0ver 70% of surface is covered in water • Temperatures between -80o C and 70o C

13. The Inner Planets • The temperatures allow water to exist in solid, liquid, and gas form • Has enough gravity to hold together its atmosphere • Atmosphere: over 100 km thick (about 62 miles) • Made of oxygen, carbon dioxide, nitrogen, argon, and other gases • 78% _____________________________ • 21% _____________________________ • 1% ______________________________ • Less than 1% _____________________ • Nitrogen • Oxygen • Argon • Carbon Dioxide

14. The Inner Planets • Mars – Called the “Red Planet” due to iron rich rock that covers the surface • Rotates around the sun in 687days, and takes 24 hours 37 min to rotate on its axis. • Atmosphere – 95% carbondioxide, very thin, with few clouds • Thin atmosphere allows the surface to be viewed from Earth with a telescope • Surface temperatures range from -140o C to 20o C

15. The Inner Planets • Water: Images show a variety of features that appear to have been made by streams, lakes, oceans, and coastlines • Mars had large amounts of liquid water in the distant past • Had to have been warmer with a thicker atmosphere • Now all the water is frozen, in the two polaricecaps and underground

16. The Inner Planets • Mars has seasons just like Earth • Because of the seasons, one ice cap grows, while the other shrinks. • As the seasons change, the process reverses itself • Mars

17. In Closing • Why is it important to learn about the other planets in our solar system?