Why do astronomers consider gamma-ray bursts to be one of the ...

[PhilipSeeMore]

Why do astronomers consider gamma-ray bursts to be one of the greatest mysteries in astronomy?
 
  A) because they are so rare
  B) because we know they come from pulsating variable stars but don't know how they are created
  C) because the current evidence suggests that they are the most powerful bursts of energy that ever occur anywhere in the universe, but we don't know how they are produced
  D) because current evidence suggests that they come from our own Milky Way, but we have no idea where in the Milky Way they occur
  E) because current evidence suggests that they come from massive black holes in the centers of distant galaxies, adding to the mystery of black holes themselves

Question 2

Suppose Mars had turned out to be significantly smaller than its current size, say about the size of our Moon. How would this have affected the number of geological features due to each of the four major geological processes?
 
  What will be an ideal response?

[yasmina]

Answer to Question 1

C
An advanced civilization lives on a planet orbiting a close binary star system that consists of a 15MSun red giant and a 10MSun black hole. Assume that the two stars are quite close together, so that an accretion disk surrounds the black hole. The planet on which the civilization lives orbits the binary star at a distance of 10 AU.

Answer to Question 2

If Mars were smaller, it would have undergone less volcanic and tectonic activity because its interior would have cooled more. With less atmosphere from less outgassing, it is likely that erosion would be less important as well. As a result, craters would be more widespread on the Martian surface.

[PhilipSeeMore]

Excellent

[kishoreddi]

Gracias!