Which list gives the astronomical objects in order of size, starting with the largest?
A: Universe - galaxy - star - asteroid B: galaxy - Universe - star - asteroid C: Universe - star - galaxy - asteroid D: asteroid - star - galaxy - Universe
Venus and Neptune are planets in our Solar System.
State two ways in which the orbits of Venus and Neptune are similar.
State one way in which the orbits of Venus and Neptune are different.
Titan is a moon that orbits the planet Saturn. The radius of its orbit is 1220000 km and its time period is 15.9 days15.9 \text{ days}15.9 days. Calculate the orbital speed of Titan in km/day\text{km/day}km/day. Give your answer to 2 significant figures.
Ganymede is a moon that orbits the planet Jupiter. Ganymede has a similar orbital period to Titan, but its orbital speed is about 2.2 times larger. Explain how this is possible.