2. Models of the Solar System Geocentric Model - Earth is considered to be the center and everything else revolves around it.

3. Heliocentric Model –The sun is the center of the solar system. Copernicus proposed that the Moon revolves around Earth, and that the apparent motion of the planets, stars, and Sun is due to Earth’s rotation.

4. Galileo Galilei found evidence supporting Copernicus’ theory and also saw moons in orbit around Jupiter. He concluded that the Sun is the center of the solar system.

5. Copernicus and Galileo thought that the orbits of the planets were circular, but a German mathematician, Johannes Kepler, discovered that they travel in ellipses, not circles.

6. OUR SOLAR SYSTEM SUMMARY Early astronomers thought the Sun, planets, and stars orbited a stationary Earth. Copernicus suggested that the Sun was the center of the solar system. Copernicus suggested that the Sun was the center of the solar system. Kepler demonstrated that each planet orbited the Sun in an elliptical pattern. Kepler demonstrated that each planet orbited the Sun in an elliptical pattern.

7. OUR SOLAR SYSTEM My Very Excellent Mother Just Served Us Nine (Pizzas) My Very Excellent Mother Just Served Us Nine (Pizzas) Solar System—The sun and all the objects that orbit around it Solar System—The sun and all the objects that orbit around it Planets reflect light, and stars emit light. Planets reflect light, and stars emit light.

8. Inner Terrestrial Planets Mercury Extreme Temperatures Extreme Temperatures Smallest Smallest Closest to the sun Closest to the sun

9. Inner Terrestrial Planets Venus Second planet from the sun. Second planet from the sun. Similar in size to Earth Similar in size to Earth Extremely thick, dense atmosphere Extremely thick, dense atmosphere Hottest average temperatures Hottest average temperatures Named after the goddess of love Named after the goddess of love Sometimes called the morning star or the evening star Sometimes called the morning star or the evening star

10. Inner Terrestrial Planets Earth Third planet from the sun. Third planet from the sun. Water can exist as a solid, liquid, and a gas. Water can exist as a solid, liquid, and a gas. Only planet not named after a character in Roman mythology Only planet not named after a character in Roman mythology

11. Inner Terrestrial Planets Mars Fourth planet from the sun Fourth planet from the sun Commonly called the Red Planet Commonly called the Red Planet Has the “sphinx face” and “pyramids” Has the “sphinx face” and “pyramids” Has polar ice caps Has polar ice caps Atmosphere is thinner than Earth’s. Atmosphere is thinner than Earth’s. Two moons, Phobos and Deimos Two moons, Phobos and Deimos

12. Outer “Gas Giants” The inner and outer planets are divided by an asteroid belt. All of the gaseous outer planets have rings and moons.

13. Outer “Gas Giants” JUPITER Fifth planet from the Sun Fifth planet from the Sun Largest planet in our solar system Largest planet in our solar system Great red spot that is a massive hurricane Great red spot that is a massive hurricane Has more than 60 moons Has more than 60 moons

14. Outer “Gas Giants” SATURN Sixth planet from the Sun. Sixth planet from the Sun. Spectacular icy rings Spectacular icy rings Second largest planet in the solar system. Second largest planet in the solar system.

15. Outer “Gas Giants” URANUS Seventh planet from the Sun. Seventh planet from the Sun. Planet rotation is on its side Planet rotation is on its side Blue in color due to methane gas Blue in color due to methane gas Has 27 moons Has 27 moons

16. Outer “Gas Giants” NEPTUNE Eighth planet from the Sun. Eighth planet from the Sun. Blue in color due to methane gas Blue in color due to methane gas Large blue spot which is a hurricane-like storm Large blue spot which is a hurricane-like storm

17. Outer “Gas Giants” PLUTO No longer considered to be a planet due to highly elliptical orbit and composition. No longer considered to be a planet due to highly elliptical orbit and composition. Does not have rings, and is not predominately gaseous only. Does not have rings, and is not predominately gaseous only.

18. Meteoroid, meteor or meteorite? A meteoroid is interplanetary material that falls toward Earth and enters Earth’s atmosphere. When a falling meteoroid burns up in Earth’s atmosphere and produces a streak of light, it is called a meteor. If the meteoroid does not completely burn up, part of it will collide with the ground, and it is called a meteorite.

19. Comets Comets are small, icy bodies that have highly eccentric orbits around the Sun. Some comets are periodic, such as Halley’s comet, which comes every 76 years (expected again in 2061).