Which of the following statements is true in the context of the formation of stars from the interstellar medium?
A) The densest interstellar clouds contain from 108-1011 atoms/cm3.
B) The densest interstellar clouds have temperatures as low as 1000 K.
C) Clouds can never resist their own gravity and eventually collapse under its influence to transform into stars.
D) Stars can form in molecular clouds when the densest parts of the clouds become unstable and contract.
D
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Kepler's Laws: It takes the planet Jupiter 12 years to orbit the sun once in a nearly circular orbit. Assuming that Jupiter's orbit is truly circular, what is the distance from Jupiter to the sun, given that the distance from the earth to the sun is 1.5 × 1011 m?
A. 3.9 × 1011 m B. 5.2 × 1011 m C. 7.9 × 1011 m D. 9.7 × 1011 m E. 3.2 × 1012 m
Saturn’s rings look bright because __________.
a. light from the Sun reflects off the material in the rings b. the material in the rings is hot and creates its own light c. light from Saturn reflects off the material in the rings
Which of the following is not a pattern of motion in our solar system?
A) Planets all orbit in the same direction. B) Planets all rotate in the same direction. C) Planets all orbit the same direction as the Sun's spin. D) Large planets all have many moons orbiting them.
What do we mean by the singularity of a black hole?
A) There are no binary black holes—each one is isolated. B) An object can become a black hole only once, and a black hole cannot evolve into anything else. C) It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions. D) It is the edge of the black hole, where one could leave the observable universe. E) It is the "point of no return" of the black hole; anything closer than this point will not be able to escape the gravitational force of the black hole.