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Screenshot Click to enlarge, it gets a bit prettier. (The scene is
just too dark for the thumbnail to look any good)

Lunar Eclipse this Wednesday

Rec 17-feb-2008 22:48

Last year I wrote about missing a total lunar eclipse due to bad weather and that next Wednesday we will have another one.

Anyway, if you live in the same timezone as I do, the partial eclipse will start at 22:42. Totality starts at 00:34 and lasts about 51 minutes. About 02:09 it will be all over.

For first time eclipse viewers, it is useful to remark that the Moon doesn't really disappear during totality: it gets a lot darker and reddish, but I hear it is very rare for it to get dark enough to make it hard to see. The exact color varies from eclipse from eclipse: it is caused by light reflect on Earth's atmosphere. If the atmosphere is clear, there are many clouds and snowy areas reflecing sunlight, the Moon doesn't get too dark and its may get an orange tinge. If some volcanic eruption throw enough particles in the atmosphere and there aren't that many white clouds or snow around, the Moon will look dark red. There is even a scale to measure this, called the Danjon Scale.

The geometry of the event is pretty good for my location: the Moon will be 67 degrees high in the horizon, probably well above the buildings nearby. The swimming pool in my building is on the top floor, so I'm thinking about watching the event over there -- if the nights keep that hot, I might as well watch it from inside the pool -- or perhaps hosting a small party with a few astronerd friends.

The picture above shows something we can't see: how the eclipse will look as seen from the Moon. From there, it will be a solar eclipse: the earth passes right in front of the Sun, blocking its light and making the Moon drown on its shadow. I actually had to cheat a bit in this picure: I increased the "ambient light" to make the Moon visible at all. But there is actually no "ambient light" in space, so if you actually were at that point, the Moon would be just a round patch of blackness. (If you have Celestia for Windows, click here to see this exact scene; under Linux, you will have copy the link manually.)

The good news is that the hot weather has been producing many near-cloudless days here lately, but there have been some rain just after sunrise every now and then. And right now it's raining quite a bit -- hard enough, in fact, to jam the satellite TV signal. Perhaps I shouldn't get my hopes too high. Wish me luck.

Addendum on Feb-21: It seems the Force was with us -- very few clouds meant the eclipse was beautiful. Sorry I don't have pictures to show -- I'd lent my tripod to a friend that's travelling and there's no way to get a decent picture without a tripod.

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