Which of the following is the best answer to the question, "Why does the Sun shine?"
A) As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.
B) As the Sun was forming, nuclear fusion reactions in the shrinking clouds of gas slowly became stronger and stronger, until the Sun reached its current luminosity.
C) The Sun initially began making energy through chemical reactions. These heated the interior enough to allow gravitational contraction and nuclear fusion to occur.
D) The Sun initially began generating energy through nuclear fusion as it formed, but today it generates energy primarily through the sunspot cycle.
A) As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.
You might also like to view...
Why do astronomers narrow their search to the "habitable zone" of other star systems?
a. the most likely place to support planets with thick atmospheres b. the least likely place to have zero ultraviolet radiation c. the most likely place with liquid water, and extraterrestrial life d. the most likely place to have oxygen in the atmosphere e. the least likely place to have wide temperature ranges on the surfaces of planets
On which planet does plate tectonics take place?
A. Venus B. Mars C. Mercury D. Earth
Compare the energy and speed of infrared and visible light. Which of the following statements is true?
A) Infrared light has higher energy, and moves faster. B) Visible light has higher energy, and moves faster. C) Visible light has higher energy, but the same speed. D) Infrared light has higher energy, but the same speed.
How many days are required for a radioactive sample, with a half-life of 5.7 d and an initial activity of 1.07 × 105 Bq, to decay to an activity of 100 Bq?
A) 57 d B) 46 d C) 68 d D) 39 d