Most interstellar dust grains are produced in
A) the Big Bang.
B) the interstellar medium.
C) the atmospheres of red giant stars.
D) supernova explosions.
E) the solar nebula.
Question 2
Current techniques can measure stellar motion to less than
A) walking speed.
B) running speed.
C) freeway speed.
D) cruising speed of an airplane.
E) orbital speed of Jupiter.