Why does Uranus lie 'on its side'

The impression that Uranus is lying 'on its side' arises from the fact that its axis of rotation is not vertical to its orbit around the sun, as in the other planets of the solar system. It is so strongly tripped that it lies almost parallel to its orbit. The probable reason for this is a collision with another heavenly body. This also probably gave rise to the narrow rings. Uranus goes around the sun once in 84 years. Since its axis of rotation is lying on one side, the poles point alternately in the direction of the sun every 21 years. There is then summer for 21 years and on the opposite side is winter.'

Why is it very cold on Neptune?

It is extremely cold on Neptune:  the ground temperature is around -220 C. The reason for this is that it is far away from the sun, almost double the distance than its neighbor Uranus. As a result, it hardly gets any heat from the sun. Because of its blue color, the eighth planet of the solar system was named after the Roman god of sea, Neptune. The blue color does not indicate liquid water, but instead its atmosphere is made of hydrogen and helium.

How do we know the 'outer planets' so well?

Much of what we know about the gas giants comes from the observations made with telescopes-with the ones that are present on the Earth as well as with the Hubble space telescope. They provide very clear pictures of the outer planets. Many pictures are transmitted to the Earth by the space probes. The most well known of these probes are Voyager 1 and Voyager 2, which started in 1977. They flew in the direction of Jupiter and Saturn, where they took the first exact pictures of the Saturn rings. Voyager 2 then flew past Uranus and Neptune for a 'big tour' of the space taking advantage of the 'slingshot' effect of the gravitational force of Saturn. As of today, both the probes have left our solar system.