GL 107 Earth Systems Science
K. Hannula
Discussion questions for 12/5/07
1. List the planets in order of increasing distance from the sun. Compare their diameter, length of day (= period of rotation), and density.
Starting from closest to the sun:
Planet | Diameter | Length of day | Density |
Mercury | 3015 miles | 59 earth days | 5.4 g/cm3 |
Venus | 7526 miles | 244 earth days | 5.2 g/cm3 |
Earth | 7920 miles | 23 hours, 56 min, 04 sec | 5.5 g/cm3 |
Mars | 4216 miles | 24 hours, 37 min, 23 sec | 3.9 g/cm3 |
Jupiter | 88,700 miles | 9 hours, 50 min | 1.3 g/cm3 |
Saturn | 75,000 miles | 10 hours, 14 min | 0.7 g/cm3 |
Uranus | 29,000 miles | 17 hours, 14 min | 1.2 g/cm3 |
Neptune | 28,900 miles | 16 hours, 03 min | 1.7 g/cm3 |
Pluto | ~ 1425 miles | 6.4 earth days | 1.8 g/cm3 |
2. How are the inner (or "terrestrial") planets different from the outer (or "Jovian") planets?
Inner planets: smaller, denser, more rock and less atmosphere
Outer planets: larger, less dense, lots of atmosphere compared to rock
3. What is Venus' atmosphere composed of? How is Venus similar to Earth? How is it different?
Venus' atmosphere is 97% carbon dioxide.
Similarities to Earth:
Similar diameter
Similar density
Both are primarily rocky planets, with well-developed atmospheres (but still much, much smaller atmospheres than the outer planets)
Both have relatively young surfaces (as determined by crater density)
Venus presumably has a crust, mantle, and core like Earth does.
Venus has shield volcanoes similar to Hawaii.
Differences:
Venus' carbon dioxide atmosphere results in extremely high temperatures (900 F!).
Venus has a similar length day and year (one side always faces sun).
Venus does not have obvious continents and ocean basins: whatever the cause of volcanism and tectonic deformation is, it can't be plate tectonics exactly as known on Earth.
4. Compare and contrast Mars and Earth in terms of 1) size, 2) surface temperature, 3) atmosphere composition.
1) Mars is smaller.
2) Mars is colder.
3) Mars has an atmosphere made up primarily of carbon dioxide and water vapor; Earth has an atmosphere made up primarily of nitrogen and oxygen.
5. Mars features a volcano the size of Ohio (Olympus Mons). What does this imply for the possibility of plate tectonics on Mars?
It means that plate tectonics as it exists on Earth can't occur on Mars. (On Earth, tectonic plates carry volcanoes on places like Hawaii away from their magma source in the mantle, preventing volcanoes from getting as large as Olympus Mons.)