Astronomy 201 

Homework FIVE


  1. Calculate the loss rate for a comet in gms/sec, assuming a particle loss rate at 1 AU of 5 x 1028 molecules per second. Assume all the molecules are water. If the comet density is 1 gm/cm3, what is the volume of ice lost if the comet loses mass at this rate for 3 months? If the comet begins with a radius of 3 km, what is the radius of the comet after one passage (and mass lost event of 3 months)?
  2. How many typical comets would it take to provide Earth's entire water supply? (Assume each comet is 80% water; assume the total water supply on the earth can be taken as the mass of the oceans, 1018 kg).
  3. If 50 billion comets have passed through the inner solar system over the age of the solar system, what is the total mass removed from the Oort Cloud and Kuiper Belt through this process?  Based on this calculation, make an estimate as to how much mass might have been lost from the Oort Cloud and Kuiper Belt over 4.5 billion years.  You will need to make assumptions as to how much mass is kicked out of these reservoirs but never makes it into the inner solar system.
  4. An object is discovered with a semi-major axis of 1.7 AU and eccentricity 0.41. What kind of object is this?
  5. About 100 metric tons of meteoritic material rain down onto Earth's surface every day!   How much mass does this add up to, as a fraction of the Earth's mass, after 4. 5 billion years, assuming this rate has been constant for 4.5 billion years? Do you think this is enough mass to substantially affect or alter the Earth?
  6. What is the 'big picture' significance of the Allende meteorite?
  7. What is the 'big picture' significance of the Murchison meteorite?

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