Which of the following types of molecule is the most abundant in ...

[saliriagwu]

Which of the following types of molecule is the most abundant in an interstellar molecular cloud?
 
  A) CO
  B) H2O
  C) H2
  D) NH3

Question 2

Explain how astronomers determine the size of an asteroid without resolving it.
 
  What will be an ideal response?

[britb2u]

Answer to Question 1

C

Answer to Question 2

The brightness of an asteroid depends on its size, distance, and reflectivity. The brightness can be measured using a telescope, the distance is known from its orbit, and the reflectivity can be measured by comparing how bright the asteroid is at visible and infrared wavelengths. A highly reflective asteroid does not absorb much sunlight and is cooler than a darker asteroid. It will therefore shine less brightly at infrared wavelengths, relative to its visible brightness, than the dark asteroid. Once the reflectivity and size are known, the size can be determined from the asteroid brightness: for a given reflectivity and distance, the brightness depends on how large the asteroid is.

[saliriagwu]

Thanks

[britb2u]

Welcome