Describe the impact the discovery of extrasolar planets h as had ...

[cookcarl]

Describe the impact the discovery of extrasolar planets h as had on the question of life on other worlds.
 
  What will be an ideal response?

Question 2

What role does hydrogen play in spectral classification?
 
  What will be an ideal response?

[ApricotDream]

Answer to Question 1

We do not yet know how common small, rocky Earth-like planets are around other stars, or what are the characteristics of their orbits. This is the primary motivation for new space-based missions. We can speculate, however, on the possibility of life on moons around the Jupiter-like planets in close-in orbits around other stars, much as we speculate on life on, e.g. Europa or Titan. These discoveries have led to the study of life in extreme environments on Earth.

Answer to Question 2

Its spectral lines are most obvious in mid-temperature stars and least obvious in both very hot and very cool stars.

[cookcarl]

Excellent

[milbourne11]

Gracias!