1. READ/play the text
2. CLICK the picture (and video)
3. TRY this:

Q1: What are rocky planets?

[Answer]

The Earth is one of several planets in our Solar System that are made of solid rock. The others we have known about for a long time are Mars, Mercury, Pluto and Venus.

To be a planet, a body must orbit the Sun, so although the Moon is bigger than the smallest planets, it orbits the Earth and so is still a moon.

Here's a note for space enthusiasts: two other small rocky planets, called Quaoar and Sedna were discovered in 2002 and 2004.They lie beyond Pluto. Perhaps there are still more to find.