Like Earth, Like Moon: A Crescent Moon Seen from Space

Bad Astronomy
The entire universe in blog form
Jan. 20 2013 8:00 AM

Phase of Beauty

Crescent Moon and Earth seen from space
Like Earth, like Moon: Two worlds seen from space.

Image credit: NASA

Astronauts, unsurprisingly, get a unique view of Earth. Their perspective removes them from the day-to-day strife those of us surface-dwellers experience, and over time they get a whole-world viewpoint. So many of them feel that way that they formed a group called Fragile Oasis, where they try to bring some of that perspective down to Earth.

Phil Plait Phil Plait

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

I follow Fragile Oasis on Twitter, where they commonly post lovely pictures taken from space. Still, I was stunned when I saw this amazing, beautiful, serene photo of our Moon at the top of this post. Here's a closer look:

The old Moon, rising over the Earth's morninglit edge.
The old Moon, rising over the Earth's morninglit edge.

Image credit: NASA

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Sigh. This photo was taken by an astronaut on the International Space Station on Sep. 4, 2010. The Moon was just a few days before new, and if I’ve pictured the geometry correctly in my head, the Moon had just risen over the Earth’s edge a few moments earlier. A minute or so later the Sun would’ve risen farther along the curve of the Earth; the thin crescent of our planet shows the space station was about to head into the daylit side of the Earth, the half facing our nearest star.

This picture possesses a simple beauty, the majesty of the Earth with our Moon so far in the distance. As a scientist I can’t help but notice how gray the Moon looks compared to the intense blue of our atmosphere. Note how dim and dark the Moon is as well; on average it reflects about a third as much sunlight as the Earth does, making it appear dusky compared to our bright, shiny planet.

As a space enthusiast I see the Moon for what it is: our nearest cosmic neighbor, but still so terribly remote in human terms it takes more than three days to get there. And I think of how no human has set foot on it since Gene Cernan stepped back on the Apollo 17 lunar module ladder more than 40 years ago.

As a human, a scientist, and a space enthusiast I can’t help but wonder: When will we disturb that gray dust once again?

As an optimist—which I will, sometimes, admit to being—I think it will be soon.

The same view, but a day later.
The same view, but taken a day later, on Sep. 5, 2010. Can you see the Moon is a slightly thinner crescent?

Image credit: NASA

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