The Milky Way Galaxy is
a. a spiral galaxy.
b. part of a cluster of galaxies that contains a few dozen galaxies.
c. about 80,000 light years in diameter.
d. All of the other choices are correct.
Question 2If the distance to the nearest star is 4.2 light-years, then
a. the star is 4.2 million AU away.
b. the light we see left the star 4.2 years ago.
c. the star must have formed 4.2 billion years ago.
d. the star must be very young.
e. the star must be very old.
Question 3The speed of light is 3.0 105 km/s, and it takes 1.3 s for light to travel from the Moon to Earth. From this information, what is the distance to the Moon?
a. 390,000 km
b. 230,000 km
c. 3.9 km
d. 2.3 km
e. 4.3 105 km
Question 4Earth has a radius of about 6400 km, the Sun has a radius of about 7.0105 km, and a rubber ball has a radius of 6.4 cm. If you were to construct a scale model of the solar system using the rubber ball to represent Earth, what is the radius of a ball needed to represent the Sun in your model?
a. 7.0 105 cm
b. 7.0 cm
c. 700 cm
d. 70 cm
e. 7000 cm