Planet Facts

1. Pluto is the smallest planet in the Solar System, smaller than Earth's Moon, and half the width of Jupiter's moon, Ganymede.

2. Pluto's journey around the Sun takes 248 Earth years. This means that, since its discovery in 1930, it still has 177 years to go until it has made a complete orbit around the Sun.

3. Nobody knows what Pluto's atmosphere contains, or even if it has an atmosphere. Any atmosphere is most likely to contain nitrogen.

4. Pluto was the only planet to have been discovered in the Twentieth Century.

5. Pluto is the only planet in the Solar System not to have been visited by a space probe.

6. Pluto's orbit is elliptical, meaning that it can come closer to the Sun than Neptune, but then go almost two billion kilometres further away from Neptune's orbit. In the picture below, you can see Pluto's orbit (in grey) and Neptune's orbit (in blue)

7. Pluto orbits the Sun on a different plain than the other 8 planets, going over them and below them.

8. Pluto has one moon, Charon, which is not much smaller than Pluto itself. No other moon is as close to the size of its planet as Charon is to Pluto. (Pluto is 2,280 kilometres wide, Charon is 1,212 kilometres wide).

9. A day on Pluto lasts for 6 days and 9 hours, meaning that it has the second slowest speed of rotation in the Solar System (after Venus, which takes 243 days to turn on its axis).

10. Pluto's orbit is elliptical, meaning that it can come closer to the Sun than Neptune, but then go almost two billion kilometres further away from Neptune's orbit.

11. Pluto is too faint to be seen with the naked eye. When viewed through a telescope, it looks like a star.

12. Pluto is cold: -233� C (-390 � F), just 40� C (72 � F) above absolute zero. At this temperature, all elements would be frozen but neon, hydrogen, and helium.