Space · Moons

Io

The most volcanic place known

You need binoculars

The yellow and orange surface of Io, covered in sulfur flows, with a plume rising up.

The numbers

Diameter: 2,270mi(3,660 km)A little more than our Moon
Active volcanoes: More than three hundred
Height of the plumes: 310mi(500 km)
One trip around Jupiter: 1.77days
When it was discovered: In 1610, by Galileo Galilei

To get an idea

Its plumes rise hundreds of miles, far higher than any volcano on Earth.

The heat that makes it erupt does not come from inside but from the stretching caused by Jupiter.

Fun facts

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

On its surface there are more than a hundred mountains, and they are not volcanoes but lifted crust.
Some of those peaks are taller than any mountain that exists on Earth.
The yellow, orange and red colors of its surface come from sulfur compounds.
Its name comes from a figure of Greek myth, loved by Zeus.
It is one of the four moons Galileo saw in 1610, called the Medicean moons.

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 Io special?

Question 2 of 5

Where does the heat that makes it erupt come from?

Question 3 of 5

How high do its plumes reach?

Question 4 of 5

Why is Io yellow and orange?

Question 5 of 5

Who discovered Io?

Riddles

I am small and should have cooled down billions of years ago, and instead I burn more than any other place around here. What keeps me warm is the giant that stretches and squeezes me without rest. What am I?

I am yellow, orange and red like a battered egg yolk, and I keep changing my face because more than three hundred mouths remake my skin. What am I?

My puffs climb hundreds of miles, something no volcano in your world could do: on me there is no air to hold them back. What am I?

Try it yourself

Activity 1

Look at the same scene the next evening: Io will have moved quite a lot, because it goes all the way around Jupiter in less than two days.

Activity 2

Bend a paper clip back and forth until it snaps, then touch it where it bent: it is warm. It is the same thing that lights up the volcanoes of Io.

The words

plume: The column of gas and dust that a volcano shoots upward.

Sources: Wikidata (Q3123), Wikipedia (Io (astronomia)).