:which of the following is true about comets in our solar system? a. being mini-stars, they are made of gas. b. they were discovered in the 17th century. c. they take roughly the same amount of time to orbit the sun. d. they all orbit the sun due to the sun’s gravity.

During the apollo moon missions, astronauts were concerned about the effects of newton's third law of motion when: o a. they ejected waste water, because they were concerned that it would push them off course. o b. they reentered earth's atmosphere, because they were carrying heavy moon rocks. o c. they took off from earth, because a large force was required to generate large acceleration. o d. they detected incoming space debris, because the inertia of the debris could damage their ship.