This chart puts the moons of the solar system into perspective

Your guide to realizing solar system scale.
By | Published: February 21, 2017 | Last updated on May 18, 2023
Elisabeth Roen Kelly / John Wenz

Our moon is not the biggest moon in the solar system — not by a long shot. In fact, the Moon is only the fifth biggest satellite in our solar system, wedged right between Io and Europa in size. The real winners are Titan and Ganymede, both of which clock in at a hair bigger than Mercury — planets in their own right.

We put together this chart to demonstrate to you just how big the biggest moon of every planet is, adding in Mercury and Pluto for good scaling opportunities. (Thank you to Elisabeth Roen Kelly for her amazing work on this.) Were we to try to cram all the larger satellites in, this would be jam packed, layer over layer. Titania, Rhea, Iapetus, and Oberon are so similar in size that we’d barely be able to cram in text in that space. 

So now when you look up in the night sky, you’ll have a rough idea of what would happen if the Moon and Ganymede swapped places.

This diagram appeared in our December 2016 issue.