What makes white-dwarf supernovae very good standard candles for distance measurements?
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
E
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Which internal heat source still generates heat within the terrestrial worlds today?
A) heat of accretion B) heat from differentiation C) heat from convection D) heat from radioactive decay
A star with a parallax angle of 1/20 arcsecond is ________
A) 20 parsecs away B) 20 light-years away C) 10 parsecs away D) 1/20 parsec away
Based on our current understanding of physics, we can understand the conditions that prevailed in the early universe as far back in time as about ________
A) 10 billion years ago B) 10-45 seconds after the Big Bang C) one ten-billionth of a second after the Big Bang D) 380,000 years after the Big Bang
The warming of the lower atmosphere (the greenhouse effect) results from the
A) absorption of long-wave solar radiation. B) reflection of long-wave terrestrial radiation. C) absorption of long-wave terrestrial radiation by atmospheric gases. D) release of atmospheric gases into the ozone layer.