Why is one side of the moon called "the dark side of the moon"? O A. The moon's rotation and revolution take the same time.
B. The moon's rotation time is exactly twice the time of its revolution.
Ο Ο
C. The moon's rotation time is exactly half the time of its revolution.

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.