Y dwarfs are substellar objects with temperature above 500 K
Indicate whether the statement is true or false
False
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Spherical Mirrors: An upright object is 50 cm from a concave mirror of radius 60 cm. The character of the image is
A. real and upright. B. real and inverted. C. virtual and upright. D. virtual and inverted.
According to the argument in the text, the Moon’s average surface temperature (since it has no atmosphere and is the same distance from the sun as the earth) should also be 255 K, or it would be if all points on its surface had the same temperature (and the Moon has the same average reflectance as the earth). But the Moon rotates very slowly relative to the sun (once a month) and has no atmosphere or ocean to redistribute energy differences. How do you think that these facts might affect the Moon’s average temperature?
A. The average should be less than 255 K. B. The average should be more than 255 K. C. The average should be the same: the energy flowing in must still balance the energy flowing out.
On an H-R diagram, stellar masses ________
A) decrease from upper left to lower right B) are impossible to determine C) are greatest in the lower left and least in the upper right D) can be determined for main sequence stars but not for other types of stars
What, approximately, are the dimensions of the smallest object on Earth that the astronauts can resolve by eye at 200 km height from the space shuttle? Assume ? = 500 nm light and a pupil diameter D = 0.50 cm. Assume eye fluid has an average n = 1.33
a. 150 m b. 100 m c. 250 m d. 25 m e. 18 m