Planets.ppt
- 1. The Planets
- 2. A. What’s in Our Solar System? • Our solar system consists of a central star (the Sun), planets, dwarf planets, moons, asteroids, comets, meteors, interplanetary gas, dust, and all the “space” in between. • Except for Earth, the planets of the solar system are named for Greek and Roman gods and goddesses.
- 3. The Relative Size of the Planets in the Solar System
- 7. B. Planets are categorized according to size and composition – Small, rocky planets are the inner planets closest to the sun – gas giants are the outer planets
- 8. Inner and Outer Planets • Inner Planets: – Mercury – Venus – Earth – Mars • Outer Planets – Jupiter – Saturn – Uranus – Neptune
- 9. 1. Characteristics of Inner Planets • They are made up mostly of rock and metal. • They are very heavy. • They move slowly in space. • They have no rings and few moons (if any). • They have a diameter of less than 13,000 km.
- 10. a. Mercury • Has a revolution period of 88 days. • Has 1000° temperature swings from day to night because there is no atmosphere to trap heat. • Is about 1/3 of Earth’s size • Is about 1/3 Earth’s distance from the sun (0.39 AU)
- 11. b. Venus • Has retrograde rotation – so the sun rises in the west and sets in the east! • Reaches 900F at the surface due to a strong greenhouse effect. • Venus has no moons and takes 225 days to complete an orbit. • Is about the same size as Earth • Is about 2/3 Earth’s distance from the sun (0.72 AU)
- 12. c. Earth • Is the only planet known to support life! • Has a surface composed of 71% water. – Water is necessary for life on Earth. • Is the basis for the Astronomical Unit (distance from sun to Earth = 1 AU)
- 13. • Mars appears red because of iron oxide, or rust, in its soil. • Mars has two moons and takes about two years to complete an orbit. • Is about ½ of Earth’s size • Is about 1 ½ times as far from the sun as Earth (1.52 AU) d. Mars
- 14. 2. Characteristics of Gas Giants • They are made up mostly of gases (primarily hydrogen & helium). • They are very light for their size. • They move quickly in space. • They have rings and many moons. • They have a diameter of 49,000 km or greater
- 15. a. Jupiter • Is the largest, most massive planet. • Takes about 12 years to orbit the sun. • Jupiter has 17 known moons. • Is about 11 times larger than Earth. • Is about 5 times farther from the sun than Earth (5.19 AU)
- 16. b. Saturn • Has many rings made of ice that extend about 260,000 miles from the surface but are less than 1 mile thick. • Has 19 known moons • Takes about 30 years to orbit the sun. • Is almost10 times larger than Earth • Is nearly ten times farther from the sun than Earth (9.5 AU)
- 17. c. Uranus • Has 21 known moons • Takes 84 years to complete one orbit. • Is about 4 times larger than Earth • Is about 19 times farther from the sun than Earth (19.1 AU)
- 18. d. Neptune • Takes 165 years to orbit the sun • Has 8 moons • Is about 3.8 times larger than Earth • Is about 30 times farther from the sun than Earth (30 AU)