How can astronomers currently determine the temperature of an ...

[fahad]

How can astronomers currently determine the temperature of an extrasolar planet?
 
  A) estimate the temperature based on the planet's distance from the star
  B) measure the drop in total infrared light when the planet passes behind the star from our perspective
  C) use spectroscopy of the planet to identify the wavelength at which its emission peaks
  D) A and B
  E) B and C

Question 2

Imagine another solar system, with a star of the same mass as the Sun. Suppose there is a planet in that solar system with a mass double that of Earth orbiting at a distance of 1 AU from the star.
 
  Thinking about Newton's version of Kepler's third law, what (approximately) is the orbital period of this planet? Explain your answer.

[Cheesycrackers]

Answer to Question 1

D

Answer to Question 2

The orbital period of the planet would be approximately the same as that of Earth (1 year). Newton's version of Kepler's third law tells us that the orbital period of an object orbiting a much more massive object depends only upon its distance, not upon its Mass. The star is this other solar system has the same mass as the Sun. Thus, even though the planet is twice as massive as Earth, its orbit will be nearly the same as that of Earth.

[fahad]

Excellent

[rachel]

Wow, this really help