Complete the sentences with : satellite, comet, planets, moons, solar system, galaxy,

1) All the ... in our ... are 4.5 billion years old.

2) Jupiter has 63 ... . The largest, Ganymede, is bigger than Mercury.

3) The stars in the Milky Way, the ... to which the sun belongs, number in hundreds of billions.

4) The gas tail of a ... always from the sun.

5) The first communications ... orbited the earth every 2 hours and 37 minutes.