What makes white-dwarf supernovae good standard candles?
A) They are very bright, so they can be used to determine the distances to galaxies billions of light-years away.
B) They should all have approximately the same luminosity.
C) They occur so frequently that we can use them to measure the distances to virtually all galaxies.
D) We have had several occur close to us in the Milky Way, so we have been able to determine their luminosities very accurately.
E) both A and B
Question 2
Which of the following statements best reflects our current knowledge about the term flife in the equation Number of Civilizations = Np flife fcivilization fnow?
A) The value of flife must be either 0 percent or 100 percent.
B) The value of flife is between 0 percent and 100 percent.
C) The value of flife is between 0 percent and 1 percent.
D) The value of flife is roughly 50 percent.
E) The value of flife is presently unknown but should be well known within just a few years.
Red-eyed and white-eyed Drosophila
Ears pulled back flat against the head with teeth bared and white of the eye showing, indicating ang
A Brown Dwarf
Frederick Douglass, having escaped from slavery in 1836, attracted large audiences as an antislavery
On November 11, 1887, four anarchists were hanged in Chicago on charges that they had thrown a bomb
A company that makes cell phones has the following cost structure. They have fixed costs of ...