Star cluster NGC 4755, also known as the Jewel Box, is located in the constellation _____
A) Aquila
B) Tucana
C) Crux
D) Pictor
C
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Chromatic aberration is a consequence of different colors in a lens having different
A) aberrations. B) frequencies. C) energies. D) critical angles. E) speeds.
Of the following distances, which is the closest an object can be to a lens of focal length f and still give a real image?
A. 3f B. 2f C. 1.2f D. 0.8f E. 0.49f
The orbits of population I stars I. are confined to disk of the galaxy. II. are very elliptical. III. are nearly circular. IV. are randomly inclined to the disk of the galaxy
a. I b. IV c. I & IV d. II & IV e. I & III
According to scientists, the naturally occurring greenhouse effect makes Earth about 31?C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?
a. Ancient fossils allow them to infer Earth's temperature at a time before our atmosphere contained greenhouse gases. b. They estimate it by averaging guesses made by many individual scientists. c. They assume that this temperature would be about the same as the temperature of Mars, which has much less of an atmosphere than Earth. d. They calculate this temperature from Earth's reflectivity and distance from the Sun.