The Earth-Moon Distance: a curious coincidence

Michael Richmond
Sep 24, 2016

Tony Dunn noted a curious fact, and inspired me to indulge my artistic impulses. Perhaps someone else will find this a useful little exercise.

Consider the average distance between the Earth and Moon. In the picture below, I've placed the objects at the proper separation relative to their size. That means that the image is a bit large and unwieldy, so click on the thumbnails below to see the full version.

How far apart are they? Well, the average distance is about 384,000 kilometers, which corresponds to just about 30 Earth diameters.

But -- and here's the interesting little fact -- that distance can also be expressed as the sum of other planet diameters ....

If you'd like to use the full-size versions of all the images, each one 4100 x 2760 pixels, then grab them below. Maybe you could make an animated GIF from them all.

• Earth and Moon with line
• Earth and Moon with 30 Earths
• Earth and Moon with other planets

Whoops, I just did: animated GIF of the images.

Sources of the images

• Mercury: taken by the Mercury Messenger spacecraft, credit MESSENGER, NASA, JHU APL, CIW, link to page containing image.
• Venus: a mosaic based on Mariner 10 images, processed by Mattias Malmer, link to page containing the image.
• Earth: image from the Deep Space Climate Observatory, credit NASA, link to page containing the image.
• Moon: image taken by Gregory H. Revera with Celestron 9.25-inch telescope, link to page containing the image.
• Mars: HST image, credit NASA, ESA, and The Hubble Heritage Team (STScI/AURA), link to page containing the image.
• Jupiter: HST image, credit to NASA, ESA, and A. Simon (Goddard Space Flight Center), link to page containing the image.
• Saturn: HST image, credit NASA, ESA and E. Karkoschka (University of Arizona), link to page containing the image.
• Uranus: Keck image, credit Lawrence Sromovsky, University of Wisconsin-Madison/ W. M. Keck Observatory, link to page containing the image.
• Neptune: Voyager 2 image, link to page containing the image.
• Pluto: New Horizons image, credit NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute, link to page containing the image.