The type of galaxy that sometimes has a distinct bar of stars running across the central region is

Aregion of space in which a measurable gravitational force is indicated by the force exerted on a test mass is called

An equinox occurs when a. neither end of earth's axis is tilted toward or away from the sun. b. the north end of earth's axis is tilted away from the sun. c. the north end of earth's axis is tilted toward the sun. d. earth's axis is parallel to the sun's rays. select the best answer from the choices provided a b c d

Positrons are spontaneously emitted from the nuclei of