Astronomy 120: Fall 2008

Homework 6: Due in October 17/20 recitation

Name ___________________________ Section _______

Q1:
Here's another "old" exam essay question that you should be ready to answer:

We'll find out towards the end of the course that it is virtually impossible to travel across the galaxy and visit other solar systems. Let's ignore that sad fact and consider exploration of a hypothetical planetary system around a nearby star. You find that the system contains a number of "terrestrial" planets and several "giant" planets. Assume we have the same tools available there as we've used to explore our solar system:

but you only have detailed information (i.e. samples) from the surface of one inner planet.

Using what you have learned about our solar system, and the methods by which we have deduced the properties of the planets and other objects based on observation and measurement, how would yo udetermine the answers to the following questions?

In your answers, be sure to state what specific measurements you would use, and what results you might expect. Answer in complete sentences, please.

  1. What would you look for to determine if very simple plant life was present on a planet?
  2. What would you expect to be the properties of planets in this solar system that have large metallic iron cores? You need two independent properties to confirm this so be sure to state and explain both.
  3. One of the planets has a mass that is 1/10 the mass of our Earth, but it lies at roughly the same distance from its parent star. it has no moon. Would you expect to find an Earth-like world, with liquid water present on the surface, and active plate tectonics and volcanos? Why or why not?

 

Q2:
One hemisphere of a (hypothetical) newly discovered satellite is found to be extremely smooth, resembling the lunar Mare. An expedition to this object returns rocks and, after radiometric dataing, they are found to have an age of about 4.2 billion years old. Why would such a finding be considered highly unusual?