The habitable zones for stars may be considerably larger if they have planetary systems containing
A) super-Earths with thick hydrogen atmospheres
B) Earth-sized planets with thick carbon dioxide atmospheres
C) super-Earths with thin hydrogen atmospheres
D) Earth-sized planets with thick methane atmospheres
A
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You want to find a mass of a star on the main sequence of the H-R diagram. What do you need?
a. The star has to be in a visual binary. b. The star has to be in a spectroscopic binary. c. You need the star's luminosity. d. You need the star's absorption spectra.
All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?
A) its mass and its stage of life B) its apparent brightness and its distance C) its age and its location in the galaxy D) its mass and its surface temperature E) its apparent brightness and its luminosity
During summer in the Southern hemisphere of Mars, winds travel
A) from the South Pole to the North Pole B) around the South Pole C) from the North Pole to the South Pole D) around the equator
A rocket obeys the principles of recoil. However, it is much more difficult to apply Newton's second law to a rocket because
A. there is actually sideways momentum, because a rocket motor is just a well-controlled explosion. B. the rocket pushes against air but the air is a fluid. C. Newton's three laws do not apply in outer space. D. as the rocket motor fires the total mass of the rocket changes.