Uranus

The planet that rolls on its side

You need binoculars

Uranus, greenish blue and almost smooth, with its axis lying down and its rings standing upright.

The numbers

Diameter: 31,763mi(51,118 km)
Tilt of the axis: 97.8°Almost lying down: the planet rolls
Length of a year: 30,589days
Average temperature: -319°F(-195 °C)
When it was discovered: March 13, 1781, by William Herschel

To get an idea

A year on Uranus lasts more than eighty Earth years, so each season lasts about twenty years.

It is the first planet in history found with a telescope: the other five could already be seen with the naked eye.

Fun facts

These are not in the book: there was no room on paper.

It is an ice giant: under the atmosphere there are squeezed water, ammonia and methane.
Its greenish blue color comes from the methane gas mixed into its atmosphere.
It is at the edge of what the naked eye can see from very dark skies, so for thousands of years it was taken for a star.
It is named after the Greek god of the sky, who in myth is the father of Cronus and the grandfather of Zeus.
It has rings too, but they are much darker and thinner than Saturn's.

Test yourself

The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.

Question 1 of 5★ is the one from your book

What makes Uranus different from all the other planets?

Question 2 of 5

How was Uranus discovered?

Question 3 of 5

How long is a year on Uranus?

Question 4 of 5

Why is Uranus greenish blue?

Question 5 of 5

What kind of planet is Uranus?

Riddles

I do not spin like a top, I roll: my axis is almost lying down and I drag myself sideways along my whole path. That is why one of my seasons lasts about twenty of your years. What am I?

For thousands of years you mistook me for an ordinary star, because I shine faintly and move very slowly. Then someone with a telescope noticed that I was drifting. What am I?

I am greenish blue because of a gas in my air, and underneath I have no rock but squeezed ices. I carry the name of the god of the sky. What am I?

Try it yourself

Activity 1

Look at the same patch of sky a few weeks apart: the little star will have moved compared with the others. It is exactly what Herschel noticed.

Activity 2

Roll a ball across a table instead of spinning it like a top: that is the difference between Uranus and all the other planets.

The words

methane: A gas that absorbs red light and makes a planet look blue.

Sources: Wikidata (Q324), Wikipedia (Urano (astronomia)) and NASA.