Two planets on the beach

How big is Mars in relation to Earth? When making such a comparison, it’s always a good idea to include objects that everyone knows. At the beginning of this century, I sometimes put a two euro coin and a euro cent on the table as a scale model. The Earth is the two euro coin and Mars is the cent. And to extend the analogy a little further: Pluto is the little sphere on the cent.

Scale comparison of the Earth and Mars, as a euro and a cent
Scale comparison: Earth and Mars as Euro coins


But since 2006 Pluto is officially no longer a planet. And I think it was about the same time that the euro cent disappeared from our wallets. That takes the fun out of that euro comparison a bit. As an alternative, in this blog post, I introduce the beach balls analogy.

This kind of comparison is really necessary. Becasue among the general public, there’s remarkably little awareness of the solar system, our immediate environment, our neighbourhood. Many people simply don’t know the difference between the solar system, the galaxy and the universe. Even Dutch national quality newspaper the Volkskrant once wrote that Jupiter is the largest planet in the universe (I’ll never forgive them).

Naming the eight planets in the right order is a basic skill that few people posses. Knowledge about the size and mutual distances of these celestial bodies is also very limited.

Beach club with three wooden chairs and on the wall a picture of Earth and Mars as beach balls in the correct proportions
The beach ball analogy

Beach balls

For some reason, many people think that Mars is bigger than the Earth. Perhaps that has something to do with its bloody history as a Roman war god. Even though we now know that this red color has more to do with rust than with blood.

In reality, our homeworld is about twice as big as Mars. The Earth has a diameter of 12,742 kilometers; our neighbor planet measures only 6,779 kilometers. These are distances that not everyone covers daily, so I have reduced the scale, in this rendering, to something more imaginable: two beach balls.

The planets Earth and Mars represented by two beach balls in the sand, on the right scale ratio to each other.
Scale comparison: Earth and Mars as beach balls


With this image , I hope to iron out a frequent misunderstanding. I’m talking about the idea that Mars is a nice backup planet, and that we can all move there if the situation on Earth becomes untenable.

Mars is a nice piece of real estate, with deep valleys, high mountains, massive ice caps and cool craters. But if we go there all together, it will be a bit tight. Not even mentioning unpleasant aspects like the low temperatures and the thin and toxic atmosphere.


I would really like to see people go to Mars to explore the planet and try to build a society there. In case another huge meteor strikes Earth, it is good to know there is a branch of civilization elsewhere.

And I also believe that it is possible to terraform Mars; in simple terms: to provide it with a more friendly climate and atmosphere. But terraforming will be an ultra-long term project and it does not make the planet bigger. It remains a relatively tiny world.

So let’s be a bit careful with that beach ball on the left.

Photo of two beach balls, Earth and Mars, framed on a tropical beach at sunset
Earth and Mars on a tropical beach (probably on Earth)

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