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09 December 2011

Get Up Early Tomorrow!

You really need to get up early tomorrow morning.  I know, it's a Saturday, and you want to sleep in, but you'll have a chance to see something pretty cool.  Basically, there will be a lunar eclipse that may coincide with sunrise.  Hopefully the weather in your area cooperates.

I know that generally a lunar eclipse is pretty ho-hum, but this particular confluence of celestial movements actually will be much more noteworthy for many of us.  Dr. Phil Plait (The Bad Astronomer) explains more:

Watch The Lunar Eclipse Saturday

Tomorrow (Saturday December 10) the Moon will pass into the Earth’s shadow, causing it to plunge into ruddy darkness, an event called a total lunar eclipse. These happen roughly twice a year somewhere on Earth, but this is the last one visible in North America for more than two years, so even though it’s in the morning it might be worth a look for you.

You can get all the info you need on watching the eclipse from my pal Alan Boyle over at the Cosmic Log, including timing, locations, and where to watch live online, too. NASA has a page with more detailed information as well. This one favors US folks farther west; the Moon will have set when the eclipse really starts for East Coast folks.

But the fun begins when the Moon starts to enter the deepest part of the Earth’s shadow at 12:45 UT (04:45 Pacific US time), and the last bit passes into shadow at 14:06 UT (06:06 Pacific). Deepest eclipse is about 25 minutes after that. Interestingly, for people in the western US, that’s around the same time as sunrise. For me, the Sun rises at 07:12 (Mountain time) Saturday, and the Moon sets at 07:14 — when it’s still partially eclipsed! Unfortunately, the mountains to the west will block my view of the setting Moon.

But for those of you with a clear horizon to the east and west, you may get an extraordinary opportunity to very briefly see the Sun and eclipsed Moon at the same time! Normally this isn’t possible; by definition the Moon and Sun have to be directly opposite each in the sky to get an eclipse at all.

But due to a quirk of geometry and atmospheric physics, it is possible. The Earth’s air acts like a lens, bending the light from objects near the horizon. Because of this effect — I give a full explanation here — you can actually see the Moon for a minute or two after it has physically set; its light is bent "around the corner", so to speak, so both it and the Sun will be over the horizon for a short amount of time. You can face west to see the setting eclipsed Moon, then turn around and see the rising Sun in the East!
CLICK HERE TO READ THE REST OF HIS EXPLANATION!

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