Chapter 24 section 2 notes
- 1. Chapter 24: Section 2 The Inner Planets
- 2. II. The Inner Planets A. Called Terrestrial Planets 1. First four planets: Mercury , Venus , Earth , Mars 2. All have a solid crust surface 3. Most have an atmosphere of some kind 4. Most have at least one moon Pgs. 646 - 650
- 3. B. Mercury Closest planet to the Sun Revolution time: 88 days Rotation time: 59 days Third smallest planet Probed by Mariner 10 (1974-1975) Imaged 45% of surface Surface crater riddled (similar to our Moon) Has large cliff lined valleys Has a weak magnetic field (indicates iron core)
- 4. B. Mercury Probed by Mariner 10 (1974-1975) Very thin atmosphere: 1. Hydrogen, Helium, Sodium & Potassium Surface Temperature: 1. Daytime: 842 o F 2. Night: -274 o F
- 5. C. Venus Second planet from the sun Revolution: 255 days Rotation: Retrograde = spins backwards Probed by Venera (Russian) in 1970 Probed by Magellan (US) in 1990 to 1994 “ Earth’s Twin Sister” Size, Mass, Gravity similar to Earth
- 6. Venus 3 . Atmosphere: Thick & toxic Air Pressure = 90 times that of Earth Mostly carbon dioxide Clouds: Rain sulfuric acid Only allow 2% of sunlight through to surface Solar energy trapped = extreme Greenhouse Effect
- 7. Chapter 23: Section 2 C. Venus (continued) Surface temperature = 878 o F Surface covered by craters, fault lines, & Volcanoes Winds = 300 km / hr.
- 8. Earth: D. Earth “ Third Rock from the Sun” Average distance from the sun = 93,000,000 miles Only planet water exists as 3 states of matter Solid, Liquid, & Gas Atmosphere protects the planet From meteor strikes (most burn up) Intense Solar Radiation (UV, X-Rays, Gamma Rays, etc.)
- 9. Ch 23: Section 2 E. Mars Fourth Planet from the Sun “ The Red Planet ” Surface mainly iron oxide dust (Rust) Revolution time: 687 days Has polar ice caps a. Northern: frozen Water (H 2 O) Southern: frozen Carbon Dioxide (CO 2 )
- 10. F. Discoveries on Mars Mariner 9 (1971–1972) Discovered dried riverbeds Olympus Mons: Largest know volcano in the Solar System Rift Zones: Deep crustal tears Viking 1 & 2 (1976) Each consisted of Orbiter & Lander Photographed entire Martian surface (Orbiters )
- 11. F. Discoveries on Mars (continued) Mars’s Atmosphere Studied meteorological, chemical, & biological aspects Discovered barren, rocky, windswept surface Atmosphere: very thin; Carbon Dioxide, Nitrogen & Argon Surface Temperatures: 95 o F (day) to -274 o F (night) Temperature changes create intense winds & dust storms NO evidence of life (past or present)
- 13. Martian Seasons Mars’s axis of rotation is tilted 25 degrees, which is close to Earth’s tilt of 23.5 degrees. Because of this Mars goes through seasons as it orbits the Sun. As one ice cap grows smaller, the other grows larger. The color of the ice caps and other areas of Mars also changes with the seasons. This is caused by the movement of dust and sand during dust storms.
- 14. Martian Moons Mars has small, crater riddled moons Phobos: 25 km in diameter Slowly spiraling toward Mars Expected impact of surface in 50 million years Deimos: 13 km in diameter Both are irregularly shaped Both orbit Mars several times a day
- 16. Mission to Mars ? How should Mars be explored? Travel time to Mars is a consideration Orbits at their closest = 1.5 years travel time Orbits at their farthest = over 5 years travel time Length of travel time invites great risks to humans Should humans explore Mars? Humans do more meticulous & detailed work than probes Zero gravity travel weakens muscles & bones Body fluids move upward (increase kidney function) Radiation exposure drastically increased Should robots explore Mars? Robots aren’t affected by 0 G’s; travel time not a factor Robots using videotronics can be controlled from Earth Signals can have up to 20 min. delay Robots cannot improvise & adapt to changing situations