Olympus Mons

The tallest mountain in the Solar System

Only spacecraft can see it

Olympus Mons seen from orbit: a very wide, gentle dome, with the dark caldera at the top.

The numbers

Height: 17mi(27 km)
Width of the base: 380mi(610 km)
What it is: A shield volcano, like the ones in Hawaii
How old it is: 3,500,000,000years
When it was first seen: In 1877, through a telescope

To get an idea

Its base is so wide that standing on it you could not tell you were on a mountain.

The crater at the top is almost two miles deep: a whole mountain would fit inside.

Fun facts

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

The outer edge of the volcano is a cliff that in some places drops almost four miles.
It is not true that the summit sticks out of the atmosphere: up there the air is still present, though very thin.
In 2004 the Mars Express probe found lava flows only two million years old.
It is not alone: it belongs to the Tharsis region, where there are three other big volcanoes.
It is much wider than it is tall: its slopes rise very, very gently.

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 is Olympus Mons?

Question 2 of 5

Why did it grow so much on Mars?

Question 3 of 5

Why couldn't you see it from the ground?

Question 4 of 5

How tall is it compared with Everest?

Question 5 of 5

Is the volcano completely dead?

Riddles

I am the tallest thing anyone knows of, and yet whoever climbed me would not realize they were climbing: my slopes are too gentle and too long. You have to look at me from the sky to see me. What am I?

I was born because the ground under me never moved, so the fire always came out of the same hole for billions of years. On Earth I would have become a chain of islands. What am I?

An astronomer mistook me for a snowy peak and gave me a name that spoke of snow. It was not snow made of water, and I am no ordinary peak. What am I?

Try it yourself

Activity 1

Pour honey onto a plate, then pour more on the same spot. A wide, low dome grows: that is how a shield volcano is built.

Activity 2

Look for a photo of Olympus Mons from orbit and one of Everest. Seen from the ground, the more impressive mountain is the second: it is all about the slope.

The words

caldera: The big hollow left at the top of a volcano after eruptions.

Sources: Wikidata (Q520), Wikipedia (Olympus Mons).