Q: A spaceship travels at a speed of 0.90c to a star that is 9.0 ly away.
1) According to a person on Earth, how long does the trip take?
2) According to a scientist ON the spaceship, how long does the trip take?
3) According to the scientist ON the spacehip, what is the distance travelled during the trip?
4) At what speed do observers on the spaceship see the star approaching them.