The Two Faces of the Moon

The far side looks *nothing* like the side that faces us. After 55 years, we may finally know why.

Ethan Siegel
Jul 9, 2014 · 7 min read
Image for post
Image for post
Image credit: Matija Pozojevic of http://www.hrastro.com/WaningGibbous_Moon/.
Image for post
Image for post
Image credit: Wikimedia Commons user Tomruen, via http://en.wikipedia.org/wiki/File:Lunar_libration_with_phase_Oct_2007_450px.gif.
Image for post
Image for post
Images (mosaic) credit: NASA / DoD / Clementine Spacecraft.
Image for post
Image for post
Image credit: ESA / P. Caril.
Image for post
Image for post
Image credit: forum user Leofidus of https://forums.robertsspaceindustries.com/discussion/17470/scale-of-planets-and-stars, of the Earth and Moon to scale.
Image for post
Image for post
Image credit: Mark Garlick / Science Photo Library, via http://www.bbc.co.uk/science/earth/earth_timeline/mass_extinctions.
Image for post
Image for post
Illustration credit: NASA.
Image for post
Image for post
Image credit: copyright Kingfisher, art by Mark A. Garlick, retrieved from http://spaceart1.ning.com/photo/birth-of-the-moon.
Image for post
Image for post
Image credit: Hawaiian lava flow by Leigh Hilbert Photography, via http://hawaiianlavadaily.blogspot.com/2010/11/surface-lava-flows-by-viewing-area.html. Impacts wouldn’t leave scars here, either.
Image for post
Image for post
Images credit: NASA / JPL-Caltech / LRO.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Ethan Siegel

Written by

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

Starts With A Bang!

The Universe is out there, waiting for you to discover it.

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch

Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore

Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store