Dive Into the Moon!

Bad Astronomy
The entire universe in blog form
March 19 2014 7:45 AM

Explore a 680 Gigapixel Map of the Moon’s North Pole

Moon north pole
If you zoom in enough, you can see Santa's summer home. Click to enselenate.

Photo by NASA/GSFC/Arizona State University

The folks on the Lunar Reconnaissance Orbiter Camera team just released an unbelievable image of the Moon: A 680 gigapixel mosaic showing details of the lunar north pole down to two meters across!

The mosaic is available as a scan-and-pan interactive page, where you can zoom in and sweep across the moonscape. There are a few interesting spots listed that you can click and zoom right to, like this lovely (and, judging from the fresh rays and sharp contours, relatively young) crater:

fresh lunar crater
They're so cute when they're young.

Photo by NASA/GSFC/Arizona State University

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You can zoom in pretty far, and I suggest making it full screen. It’s almost overwhelming at that size.

The mosaic is a combination of 841 tiles; the raw file (which, understandably, they don't make available for download) is well over three terabytes in size. As for the original images, LRO is in a polar orbit around the Moon, meaning it’s moving in a mostly north-south manner. As it orbits, the Moon slowly spins underneath it, so eventually LRO sees the entire lunar surface. Due to the geometry of the orbit, this means the terrain it sees at a given latitude has roughly the same lighting. That’s important: A crater looks very different when the Sun is low (and shadows long) compared with at noon, when the Sun is high (and shadows nonexistent).

So you can think of the mosaic as made up of a series of concentric rings of parallel longitudes, each with about the same Sun elevation, with the Sun getting lower as you move northward (because at any given time, the Sun is lower the farther north you go). That’s why the overall mosaic looks flatter near the edge and bumpier in the middle: At the pole the shadows are longest, and you see the contours of the terrain better.

And how much of the Moon does this mosaic cover? A total of 2.5 million square kilometers, or just about a million square miles! That’s a lot of Moon. To give you an idea of the area, here’s the mosaic overlaid on a map of the United States:

Moon map and the US
If you get caught between the Moon and New York City... Click to enarthurnate.

Photo by NASA/GSFC/Arizona State University

Yegads. And all of that is mapped, down to a resolution of a few meters per pixel. That’s astonishing. And it makes me wonder: Will future explorers use maps like this as they bounce around the Moon’s surface, prospecting, or running experiments, or simply going out for a stroll?

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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