1. Our Solar System How it Formed & the Inner Planets Chapter 19 & 20

2. How Our Universe Began…The Big Bang A massive star exploded in space and set off a series of events to form our solar system The shockwave made a nebula contract and rotate, forming a flat disk with temperatures steadily increasing Nuclear fusion began in the center of our solar system, forming our Sun The remaining gas and dust condensed to form the planets

3. Our Sun The closest star to us does not actually have a surface It is a large ball of gas made mostly of hydrogen and helium held together by gravity

4. Answer the Questions about the SunSun 1.How far away is the Sun? 93 million miles 2.T or F. The Sun has no solid surface. 3.How far away is the Sun’s core from its surface? Half million miles 4.What process burns the gas in the Sun? fusion 5.Hydrogen atoms collide with such force, they fuse and make helium. 6.Energy moves toward the surface through radiation. 7.What are the cooler spots on the Sun called? sun spots 8.What is responsible for solar flares? magnetism 9.Energized particles are flung out on solar wind. When the particles reach Earth, our atmosphere deflect most of them. A few attach themselves to magnetic lines at the North & South poles and strike molecules of air. The air glows with fantastic light called auroras. 10.Even moonlight is produced by the Sun.

5. Geocentric vs. Heliocentric Early scientists thought that everything in our solar system revolved around the Earth (geocentric) Copernicus later proved that the Sun is the center of our solar system, with all the planets revolving around it (heliocentric) Nicolaus Copernicus

6. Planetary Orbits We have day and night because the Earth rotates on its imaginary axis The Earth makes one revolution around the Sun in 1 year The revolutions of planets are not circular, but elliptical, as proven by Kepler Kepler also proved that planets seem to move faster when they are closer to the Sun because of the strong pull of gravity the closer you are

7. Our Beautiful Earth We are at the unique position in our solar system that allows life to exist We have an atmosphere that protects us and provides us with life We have water in all three states of matter We have seasons due to our tilt on our axis…tilted away, we have winter, tilted toward we have summer Our orbit is eccentric, which means that at certain times in our orbit, we are closer to the Sun than other times

8. The Terrestrial Planets Terrestrial means “ Earth-like ” Also called the inner planets All have hard, rocky surfaces on which to land Are closest to the Sun Some have moons, some do not

9. Mercury The first mission to Mercury was by Mariner 10 in 1974 Heavily cratered Has a very thin atmosphere made of sodium, potassium, hydrogen, and helium Because there is not much of an atmosphere, the days are extremely hot and the nights are extremely cold The solar winds from the Sun blow away most of its atmosphere One day on Mercury is the equivalent of 59 Earth days !

10. Venus: Earth’s Twin The only three things Venus and Earth have in common is size, density, and mass Has retrograde rotation, which means when viewed from its north pole, it rotates clockwise. Has about 90 times more pressure at sea level compared to Earth Atmosphere is made of carbon dioxide and sulfuric acid Has a runaway greenhouse effect, so temperatures are VERY hot all the time! The Magellan space probe mapped the entire surface of Venus from 1990-1992

11. Mars The most studied planet in the solar system Viking 1 and 2 in 1976 took a lot of pictures of Mars’ surface and analyzed it’s atmosphere Mariner 9 in the early 90’s discovered 3 things: 1. Long channels that may have carried water 2. Olympus Mons, the largest shield volcano in the solar system 3. Valles Marineris, a rift zone with past tectonic activity Has two polar ice caps of carbon dioxide Soils are reddish in color because of the iron contained in it Mars’ 2 moons, Phobos and Deimos

12. Most of us don't have an idea of the relative size of the planets and Sun, but it's rather dazzling to see it presented this way.

13. Take a Look at This…

14. Holy Cow!…

15. Are You Kidding?!…

16. Antares is the 15th brightest star in the sky. It is more than 1000 light years away…