Rocky planets and gas planets: reading a data table
The solar system is the Sun and eight planets that orbit it on elliptical paths at different distances. The four inner planets are Mercury, Venus, Earth and Mars. They are rocky. The four outer planets are Jupiter, Saturn, Uranus and Neptune. They are gas planets, made of gas and ice, and have no solid crust. Atmospheres differ. Venus and Mars have mostly carbon dioxide, and Venus’s is very dense. Earth’s is mostly nitrogen and oxygen. Jupiter and Saturn have mainly hydrogen and helium. Uranus and Neptune have hydrogen, helium and some methane. Mercury has only a very thin envelope of gas. Mars is called the Red Planet and Neptune looks blue. Earth has many volcanoes, while Mars shows signs of old volcanoes and none are known to be active now. The diameters of the planets help us put them in order of size.
| Order by size | Planet | Diameter (km) |
|---|---|---|
| 1 | Mercury | 4878 |
| 2 | Mars | 6787 |
| 3 | Venus | 12120 |
| 4 | Earth | 12756 |
| 5 | Neptune | 49660 |
| 6 | Uranus | 51118 |
| 7 | Saturn | 120536 |
| 8 | Jupiter | 142948 |
| Planet | Main gases |
|---|---|
| Venus, Mars | carbon dioxide |
| Earth | nitrogen, oxygen |
| Jupiter, Saturn | hydrogen, helium |
| Uranus, Neptune | hydrogen, helium, methane |
Planet cards. Make eight cards with a planet’s name and one fact on each. Lay them out in order from the Sun, then in order of size. Make up a pretend planet X on a ninth card, with a diameter of 30000 km and an atmosphere of hydrogen and helium, and decide where it fits in size and whether it is rocky or gas.