This multiple exposure photograph shows the apparent retrograde motion of Mars. To make this picture, the photographer needed to combine individual photos of Mars taken over a period of
A) one full night.
B) about one hour.
C) about 3 nights.
D) several months.
D) several months.
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Which space telescope is observing X-rays?
A. the Spitzer Space Telescope B. the Hubble Space Telescope (HST) C. the Chandra Observatory D. the Extreme Ultraviolet Explorer (EUVE)
According to the Big Bang theory, atoms would have likely begun to form after approximately
A. 0.5 second. B. 10 billion years. C. 1 year. D. 400,000 years. E. 3 seconds.
Two solenoids are each made of 2 000 turns of copper wire per meter. Solenoid I is 2 m long, while solenoid II is 1 m long. When equal currents are present in the two solenoids, the ratio of the magnetic field BI along the axis of solenoid I to the magnetic field BII along the axis of solenoid II, BI/BII, is
a. 1/4. b. 1/2. c. 1. d. 2 e. 4.
Fill in the blank in the following chemical reaction thatoccurs in the Sun:Deuterium+proton=??+ energy:
a) deuterium-2 b) hydrogen-1 c) helium-3 d) carbon-12 e) helium-4