Why can one not use quasars to check the Hubble relation relating distances of objects to their velocity of recession?
What will be an ideal response?
The Hubble relation requires that the velocity of recession (or better, the redshift) and the distance to objects at cosmological distances be known. But astronomers do not know the distances to quasars except through using the Hubble relation. Quasars do not appear to be a standard candle, and most are variable in their luminosity over time as well.
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A spinning neutron star has been observed at the center of a
A) supernova remnant. B) planetary nebula. C) red supergiant. D) protostar.
Auroras near the poles of the planets
a. are found on Earth. b. are found on Jupiter. c. indicate the presence of a magnetic field. d. occur when particles in the solar wind hit a planet’s atmosphere. e. all of the above.
A small airplane with a wing span of 12 m flies horizontally and due north at a speed of 60 m/s in a region where the magnetic field of the earth is 60 mT directed 60° below the horizontal. What is the magnitude of the induced emf between the ends of the wing?
a. 50 mV b. 31 mV c. 37 mV d. 44 mV e. 22 mV
Listed following are characteristics of the atmospheres of Venus, Earth, and Mars. Match each atmospheric characteristic to the appropriate planet.
