Large meteoroids are thought to collide with Earth: A) at ...

[cnetterville]

Large meteoroids are thought to collide with Earth:
 
  A) at least once a decade.
  B) about once a century.
  C) a few times in every million-year period.
  D) once every billion years.
  E) never; only comets are thought to collide with Earth.

Question 2

How does gravity lensing let us find massive dark objects?
 
  What will be an ideal response?

[brittiany.barnes]

Answer to Question 1

C

Answer to Question 2

When a black hole or brown dwarf passes between us and a bright star, the gravity of the dark object can bend and focus the light of the distant star, making it brighten temporarily. The more massive the unseen object, the longer this brightening will last.

[cnetterville]

Thanks for the timely response, appreciate it

[milbourne11]

Excellent