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Emily LakdawallaJuly 10, 2013

Scale comparisons of the solar system's major moons

Here's a presentation slide I've been meaning to put together for a while. It shows the major moons of the eight planets, to scale with each other. Below is a labeled version. You can download one without text here, and if you scroll down I've got a couple of alternative layouts.

Note: it's been pointed out to me that the Callisto image is from Voyager, not Galileo. I'll fix the text on the image eventually. --ESL

The Solar System's Major Moons

Montage by Emily Lakdawalla. The Moon: Gari Arrillaga. Other moons data: NASA/JPL. Processing by Ted Stryk, Gordan Ugarkovic, Emily Lakdawalla, and Jason Perry.

The Solar System's Major Moons
The Solar System contains 18 or 19 natural satellites of planets that are large enough for self-gravity to make them round. (Why the uncertain number? Neptune’s moon Proteus is on the edge.) They are shown here to scale with each other. Two of them are larger than Mercury; seven are larger than Pluto and Eris. If they were not orbiting planets, many of these worlds would be called “planets,” and scientists who study them are called “planetary scientists.”

Here are some alternative unlabeled versions:

The Solar System's Major Moons (sorted by location)

Montage by Emily Lakdawalla. The Moon: Gari Arrillaga. Other moons data: NASA/JPL. Processing by Ted Stryk, Gordan Ugarkovic, Emily Lakdawalla, and Jason Perry.

The Solar System's Major Moons (sorted by location)
The Solar System's Major Moons (scattered)

Montage by Emily Lakdawalla. The Moon: Gari Arrillaga. Other moons data: NASA/JPL. Processing by Ted Stryk, Gordan Ugarkovic, Emily Lakdawalla, and Jason Perry.

The Solar System's Major Moons (scattered)

For the next one, I used a different Iapetus image, because it's adjacent to the Uranian moons Oberon and Ariel for which we don't have good lower-phase (fuller) global views; putting in the higher-phase one I used above made it look too big. Ganymede looks a little small for the same reason, and also because Titan's atmosphere makes it look bigger than it actually is.

The Solar System's Major Moons (ordered by size)

Montage by Emily Lakdawalla. The Moon: Gari Arrillaga. Other moons data: NASA/JPL. Processing by Ted Stryk, Gordan Ugarkovic, Emily Lakdawalla, and Jason Perry.

The Solar System's Major Moons (ordered by size)

Read more: pretty pictures, amateur image processing, scale comparisons, presentation slides, the Moon, Jupiter's moons, Io, Europa, Ganymede, Callisto, Saturn's moons, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Iapetus, Uranus' moons, Neptune's moons, Triton

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Emily Lakdawalla

Senior Editor and Planetary Evangelist for The Planetary Society
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