1.
a) Describe the evidence that the Galilean satellite Europa has a subsurface ocean.
b) What keeps that ocean in liquid form?
c) What source of energy is likely to be available to life on Europa?
2.
a) If you poured a jug of water onto the surface of Mars, what would happen to it?
(hint -- there’s 2 steps to the answer). b) How must the Martian atmosphere have been different when the surface was warmer and wetter?
3.
Consider a star that has a mass of 1.8 times that of the Sun. Determine the lifetime of this star by scaling to the lifetime of the Sun (note from the lecture notes how the lifetime depends on the mass of the star). Explain why we might conclude that this lifetime is unfavorable for the emergence of advanced life forms.
4.
Consider a “super-earth” planet having a mass equal to twice the Earth’s mass, and the same density as the Earth.
a) What is the radius of this planet, in units of the Earth’s radius? (Be sure to show how you got your answer for these numerical questions.)
b) By what factor would your weight be larger on this planet than it is on Earth?
c) Offer a few thoughts on how the size of this super-earth planet could affect its habitability, considering how the size might affect plate tectonics, the atmosphere,
5.
What is a “hot Jupiter”? In what way did the discovery of hot Jupiters call into question the standard nebular theory for the formation of our Solar System? How might the nebular theory be reconciled with hot Jupiters?
6.
What is the gravitational lensing signature of a planet orbiting a star? Draw a picture of the spatial relationship between the star being lensed, the planet, and the star around which the planet is orbiting. Also, draw a typical light curve showing how the planet manifests itself.
7.
Explain why there is a strong bias for the presently most successful planet-hunting techniques to find planets close to their parent star. Which planet-hunting techniques are best suited for finding planets that orbit their parent stars at large distances?
8.
The Earth reflects 29% of the visible light that hits it. The Earth is 1.5 x 108
km away from the Sun, and its radius is 6378 km. If you were gazing at our solar system from around some distant star using visible light, how much brighter would the Sun appear to be than the Earth? (hint: what fraction of the Sun’s light does the projected disk of the Earth intercept?) Comment on why it might be difficult to detect the Earth in the immediate presence of the Sun.
9.
Greenland is approximately 700 x 2400 km in extent, with an average ice cover that is about 1.5 km thick. Suppose all the Greenland ice were to melt. By approximately how much would this raise the level of Earth’s oceans? Assume that oceans cover 70% of the Earth’s surface, and ignore the density difference between water and ice. (strong hint: dividing the volume of melted water by the surface area of the oceans will tell you how much the ocean depth will increase.)
10.
Wikipedia tells us that the best recent estimates for the number of eukaryotic species on Earth, including both aquatic and terrestrial species, is somewhere between 5 and 9 million (
https://en.wikipedia.org/wiki/Global_biodiversity
). Only 1.5 to 1.9 million species have so far been catalogued. Because of continuous habitat “appropriation” by humans, and the effects of climate change, it has been estimated that we lose one species every 20 minutes. If that is correct, when will the Earth have lost 50% of all species. State clearly when you decide to start your clock… human-induced species loss has already been under way for some time.