Assignment:
PLANETARY SURFACES AND INTERIORS
1. What are the three principal classes of rocks? How are they formed? What class of rock would we expect to be common on Venus? What class of rock would we be extremely surprised to find on Venus? Explain.
2. Oceanic crust on each side of the Mid-Atlantic Ridge spreads away from the ridge at a speed of approximately 1 cm/year.
a. Assuming a constant rate of spreading of the ocean floor in the geologic past, at this speed, how many years would have been required for Europe and North America to have moved from being in contact to their present separation of about 4000 km?
b. As the rock cools, the direction of the geomagnetic field determines the direction of the rock's permanent magnetization. However, the geomagnetic field reverses its direction approximately every 450,000 years (with the actual reversal taking a few thousand years). How wide are the resulting stripes of opposite magnetization on the ocean floor?
See pp. 45-46 of the textbook for additional discussion.
3. In Earth's early history, nearly all of the carbon was in the atmosphere in the form of carbon dioxide. However, now nearly all the carbon on Earth is locked up in the form of carbonate rocks.
a. Briefly summarize the steps involved in the inorganic carbon cycle.
b. How has the inorganic carbon cycle transferred carbon from the atmosphere to the solid Earth? See p. 42 of the textbook for additional discussion.
4. Martian ice caps contain a substantial amount of water ice. The northern ice cap has a diameter of about 1000 km and an average thickness of 2 km. The smaller southern polar cap has a diameter of 400 km and an average thickness of 3 km.
a. To what average depth would Mars be covered if all of this ice melted? Assume the ice caps to be circular and take the densities of water and ice to be approximately equal.
b. Look up the average depth of Earth's oceans and comment on the relative amounts of water (i.e. relative to the size of the planet) on Earth and Mars.
5. In order to lose sufficient energy to achieve a close orbit around the Sun, the Parker Solar Probe will complete seven flybys of Venus, using its gravity as a slingshot. On the first flyby it came within 2400 km of the planet's surface. What was the probe's acceleration at the point of closest approach?
6. The moment of inertia of a sphere can be written in the form I= aMR2, where and are the mass and radius of the sphere.
a. Use the above formula to calculate the value of the parameter for Jupiter. Jupiter's moment of inertia about the polar axis is 2.46× 1042kg m2. Use the equatorial radius in your calculation.
b. What does your result say about the distribution of mass inside Jupiter compared to a ball of uniform density? Is Jupiter's mass concentrated towards the centre or towards the surface? Explain.
c. What process was responsible for the redistribution of mass inside Jupiter from a uniform distribution?