Sunrise on the Moon
Photo by Thierry Legault, used by permission
Photo by Thierry Legault, used by permission
The picture above is likely the newest new Moon you’ll see: The
crescent above is actually a record-breaker; the thinnest crescent Moon
ever photographed!
It was taken by the astrophotographer Thierry Legault, who (as oxymoronic as it is) routinely takes extraordinary photos. He shot it from his backyard near Paris on Monday
at 07:14 UTC, when the Moon was a mere 4.4 degrees from the Sun. For
comparison, the Sun and Moon are about the same size in the sky, just
0.5 degrees in diameter.
The geometry of this is interesting. Back in 2010, Legault took a similar shot when the Moon was a wee bit farther from the Sun, and I explained it all then
if you want details. But in a nutshell, the Moon’s orbit is tilted a
bit with respect to Earth’s, so it doesn’t pass directly in front of the
Sun every orbit (which is why we don’t get a solar eclipse every
month). Depending on the geometry at new Moon, it slides near the Sun, though never getting more than about 5 degrees away.
Therefore, at one particular moment, in the sky the Moon will be as
near the Sun as it can get for that particular month. It was at that
moment that Legault took the picture above. He got the timing to within a
minute of the actual moment of newest Moon, so only the thinnest slice
of the lit lunar landscape was visible from Earth.
As a reference, here is how much of the Moon was lit at that time:
The thin white line: The phase of the Moon, with a teeny sliver lit, when Legault took his photo.
Photo by USNO
Photo by USNO
I got that from the U. S. Naval Observatory,
and shows the current phase of the Moon. You can see that the vast
majority of the Moon was dark, with only the narrowest sliver lit at the
top. (I rotated the image to match the actual photo.) Legault had to
use a computer-programmed telescope to find it at all.
Because the Moon was so faint and the Sun (and sky around it) so
bright, he set up a piece of wood with a small circular hole in it to
cut down on sky glare and used a near-infrared filter, where the sky is
even fainter. Even so, this was an incredibly difficult shot to take,
and he deserves kudos for it. For the record, I’ll note the Moon can get
even closer to the Sun than this, making for an even more difficult
picture. But if anyone is up to the task to snap that and break this
current record, it’s Thierry!
Related Posts (featuring Legault's work):
posted by Pieface @ 1:20 PM
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