Collisions between galaxies are thought to A) be commonplace. ...

[cdr_15]

Collisions between galaxies are thought to
 
  A) be commonplace.
  B) have stopped about 5 billion years ago.
  C) be extremely rare.
  D) have never occurred.
  E) have only occurred between 10 and 15 billion years ago.

Question 2

What is the current limit to distances we can measure via parallax, until the results of the new Gaia mission become available?
 
  A) about 100 light years B) about 1000 light years
  C) about 100,000 light years D) about 10,000 light years

[scikid]

Answer to Question 1

A

Answer to Question 2

B

[cdr_15]

Thanks

[scikid]

Welcome