Suppose that an ancient civilization had built a stone structure ...

[mwit1967]

Suppose that an ancient civilization had built a stone structure 6000 years ago to point towards a bright star as it rose.
 
  Would that structure still point at that star today? If not, why not, and what information would archaeoastronomers need to figure out which star the structure pointed at?

Question 2

In the Drake equation (Number of Civilizations = NHP  flife  fciv  fnow), what do we mean by fnow?
 
  A) the fraction of civilizations in the universe that currently are sending messages to us
  B) the fraction of planets in the galaxy on which a civilization could theoretically develop right now
  C) the fraction of all species ever to exist that we currently are aware of
  D) the fraction of planets with civilizations at the present time (as opposed to only in the past or future)

[catron30]

Answer to Question 1

Because of the precession of Earth's axis, the structure would no longer point at the original star's rising location. However, if scientists could determine the age of the structure, they could determine which stars had risen along the direction the structure pointed.

Answer to Question 2

D

[mwit1967]

Excellent

[irishcancer18]

Gracias!