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Author Question: A standard candle is A) a 7-cm-long wax candle. B) another name for a main-sequence star. C) ... (Read 224 times)

maegan_martin

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on: Jul 27, 2018
A standard candle is
 
  A) a 7-cm-long wax candle.
  B) another name for a main-sequence star.
  C) another name for a barred-spiral galaxy.
  D) a light source of known luminosity.

Question 2

Briefly summarize current knowledge about the term Np in the equation Number of Civilizations = Np  flife  fcivilization  fnow.
 
  What will be an ideal response?


potomatos

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Reply #1 on: Jul 27, 2018
Answer to Question 1

D

Answer to Question 2

We have evidence now for more than a dozen planets around other stars, and evidence for protoplanetary disks around many more stars. Although we cannot yet give a precise value to Np, it now seems likely that it is quite largeperhaps as large as the number of stars in the Milky Way Galaxy.


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