Now, you might have learnt what are inner and giant planets. But do you know about outer planets?

The outer planets are Uranus, Neptune and Pluto (not anymore). Unlike other planets, these outer planets were completely unknown to ancient astronomers. They were so far away and also so faint. Uranus was only discovered in 1781 while Neptune was discovered in 1846 whereas Pluto was discovered in 1930. Uranus and Neptune are both gas giants like Jupiter and Saturn.

- Uranus


Uranus is actually the seventh planet from the Sun in the solar system. Unlike any of the other planets, Uranus does not spin on a slight tilt angle. Instead, it is tilted right over and rolls round the Sun on its side, like a giant bowling ball.





Now, let's watch a documentary on Uranus. Enjoy!





- Neptune

Neptune is the eigth planet from the Sun in the solar system. As it is so far away from the Sun, it took 16479 years to orbit around the Sun. So Neptune's year is 16479 of ours. Neptune is also greeny blue as its surface is completely covered in immensely deep oceans of liquid methane (natural gas).


- Who found Neptune?


Two mathematicians, John Couch Adams in England and Urbain le Verrier in France, predicted that where Neptune should be from the way its gravity disturbed Uranus's orbit. Johan Galle in Berline spotted it in 23 September 1846.


Now, let's watch an interesting video on Neptune. Enjoy!