Earth-and-Sun Diamond Ring

The penumbral lunar eclipse on February 9th wasn't widely viewed. It couldn't be seen for much of the Americas or from western Europe, and even those in Asia who looked up at the full Moon saw only a dusky shading draped over part of the lunar disk.

Earth-Sun diamond ring
On February 9, 2009, as the Japanese lunar orbiter Kaguya looked on, Earth (large ring) and Sun rose together over the lunar landscape. Click here for a larger view.
But the view from the Moon was something else altogether! Take a look at this view captured by Kaguya, which has been orbiting there since September 2007. On eclipse day, a high-def television camera aboard Kaguya (supplied by Japanese media giant NHK) captured Earth rising over a darkened lunar landscape with the Sun peeking out from behind our home planet.

It's a fortuitous alignment of spacecraft, Moon, Earth, and Sun that reminds me of the classic opening scene from 2001: A Space Odyssey! (Were Arthur Clarke and Stanley Kubrick channeling the mythic Japanese Moon princess Kaguya? Hmmm.)

There's a thin ring of light encircling Earth's disk (except at the bottom, which hasn't yet risen above the lunar horizon). This is sunlight refracted through our atmosphere. Curiously, the ring isn't red, as I thought it would be, due to the atmosphere's scattering away all the blue light — this filtering is what gives total lunar eclipses their ruddy cast.

In any case, this remarkable image came to light, so to speak, in a release made public yesterday on a Kaguya website maintained by the Japan Aerospace Exploration Agency (JAXA). I had to root around a little to find the PDF presentation (in Japanese) featuring this view.

I didn't see any indication of the time and Kaguya's location when the camera was rolling. But a little diddling with Starry Night suggests it must have been near mid-eclipse (14:38 Universal Time on February 9th) with the craft positioned 60 miles (100 km) above a spot that's roughly 110° west, 42° north.

The presentation also mentions the location where one of Kaguya's small relay satellites, crucial in the creation of far-side gravity maps, crashed into the Moon out of view from Earth at 159.03° west, 28.21° north. JAXA officials expect that Kaguya itself will slam into the Moon sometime in June.

8 thoughts on “Earth-and-Sun Diamond Ring

  1. Eric F. Diaz

    That’s just truly amazing–a total solar eclipse and diamond ring effect seen from the moon! I agree, it is reminiscent of the classic opening scene from 2001: A Space Odyssey! Thanks for finding this image.

  2. Jacques Millet

    During a lunar eclipse, Earth’s shadow on the Moon is red in the middle but turns to grey closer to the edge. So, it’s normal, as the sun is still visible from the moon that the ring around is mostly white. If the Sun were to go closer to the center, the ring would become redder and less bright as the sky appears during sunset in a clear sky. JM

  3. Fred ShumanFred from Laurel, Md

    Taking the lower left corner of the photo as (0,0), and the upper right as (1,1), there is a bright spot at about (0.2, 0.4), and another, fainter one at around (0.93, 0.15), with the Sun centered around (0.75, 0.2). The two bright spots seem to be quite similar in size and shape, while differing in brightness, and aligned on opposite sides of the Sun’s image. They look to me like optical artifacts–internal optical reflections. Either that or giant blancmange aliens from the planet Skyron in the galaxy of Andromeda, and who mean to win Wimbledon. (Tip-o-the-hat to Monty Python’s Flying Circus.)

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