Which list gives the astronomical objects in order of physical size, starting with the smallest?
A: Asteroid - planet - star - galaxy B: Galaxy - star - planet - asteroid C: Planet - asteroid - star - galaxy D: Asteroid - star - planet - galaxy
Mars and Uranus are planets in our Solar System.
(i) State two ways in which the orbits of Mars and Uranus are similar.
(ii) State one way in which the orbits of Mars and Uranus are different.
Deimos is a moon that orbits the planet Mars. The radius of its orbit is 23500 km and its orbital period is 1.26 days1.26\text{ days}1.26 days.
Calculate the orbital speed of Deimos in km/day\text{km/day}km/day. Give your answer to 2 significant figures.
Phobos is another moon orbiting Mars. If a hypothetical moon orbiting Mars has a similar orbital period to Deimos, but its orbital speed is 2.5 times larger, explain how this is possible.