In 1919, general relativity was tested by measuring the deflection of starlight by the Sun. What event made this measurement possible?
A) a total solar eclipse
B) a rare alignment in which some stars were positioned almost perfectly behind the Sun as viewed from Earth
C) the first international treaty in which astronomers from different nations all worked together
D) Einstein's personal permission for the measurements to be carried out
A) a total solar eclipse
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What is the wavelength associated with the electron in the n = 2 state of hydrogen?
A) 3.32 × 10-10 m B) 2.03 × 10-10 m C) 6.66 × 10-10 m D) 4.63 × 10-10 m E) 8.17 × 10-10 m
The carbon-nitrogen-oxygen (CNO) cycle works best in temperatures:
A) lower than 10,000,000 K. B) higher than 16,000,000 K. C) higher than 11,000,000 K but lower than 12,000,000 K D) higher than 13,000,000 K but lower than 15,000,000 K
Universal time, or UT, is
A) another name for standard time. B) the mean solar time in Greenwich, England. C) the apparent solar time in Greenwich, England. D) a timekeeping system based on careful observations of positions of stars throughout the universe.
When will the full moon be highest above the southern horizon for an observer in the Northern Hemisphere?
a. at midnight near the summer solstice b. at midnight near the vernal equinox c. at midnight near the winter solstice d. at midnight near the vernal equinox e. The angle between the southern horizon and the full moon at midnight does not change with the seasons.