The Eight Planets
≈ 20 minEight planets travel around the Sun. In order of distance, starting closest:
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
They fall into two clear groups:
| Group | Planets | What they are like |
|---|---|---|
| Inner (rocky) planets | Mercury, Venus, Earth, Mars | small, solid rocky surfaces you could stand on, few or no moons |
| Outer (giant) planets | Jupiter, Saturn, Uranus, Neptune | huge, made mostly of gas and ice with no solid surface, many moons, rings |
A few facts worth carrying:
- Mercury is the closest to the Sun and the smallest planet.
- Venus is the hottest, because a thick blanket of gas traps the heat — hotter even than Mercury.
- Mars looks red because its dust is rich in iron, which has rusted.
- Jupiter is by far the largest planet: all the others would fit inside it.
- Saturn has the brightest ring system, made of countless pieces of ice and rock.
- Neptune is the furthest planet from the Sun.
Worked example — where does Pluto fit in?
Pluto used to be called the ninth planet. Astronomers later agreed on a stricter definition of "planet", and Pluto did not meet all of it — it is small and shares its region of space with many similar icy objects. It was reclassified as a dwarf planet in 2006.
Notice what happened: nothing about Pluto changed. The definition changed. That is science working properly — when better evidence arrives, scientists rewrite the rule rather than defend the old one.
Which planet is closest to the Sun?
The largest planet in our solar system is ______.
Which list gives the four inner, rocky planets?
Saturn is the th planet from the Sun and Neptune is the th. How many planets lie between them?