Saturday, March 03, 2007

Total Eclipse of the Moon

Right now, at 20:18:11 UT to be precise, the Moon is entering the so-called penumbral region of the shadow cone the Earth is casting into space - that's the beginning of a total eclipse of the moon! Clifford has linked to some beautiful photos of the "Red Moon", as it is sometimes called because of the reddish glow caused by light scattered in the Earth's atmosphere that makes in the geometric cone of the shadow.

If you want to know if you can see it, depending on where you live, you can have a look at this map, provided by NASA's eclipse guru Fred Espenak:

(Source: NASA)

In the central, white zone, you can, in principle, see the whole eclipse. The outer lines mark the phase of the eclipse at moonrise (for the Americas) or moonset (for Asia and Australia). The labels P1, U1, U2, U3, U4, and P2 correspond to the different phases of the eclipse, the entering of the penumbra (P1) and the umbra (U1), the begin and end of the total eclipse (U2 and U3), and the leaving of the umbra (U4) and penumbra (P4). So, if you live on the east coast of the US, the beginning of the total eclipse is just at moonrise (U2).

(Source: NASA)

Most spectacular, of course, is the phase if total eclipse from 22:44:13 UT to 23:57:37 UT, with the moment of greatest eclipse at 23:20:56 UT.

Of course, a dense cover of clouds can spoil the show - that's what seems to happen here in Frankfurt am Main. For all of us who cannot see anything, either because of clouds, or because you are living in the "wrong" hemisphere, the German association of amateur astronomers has organised a

from a place in the Siebengebirge near Bonn. So far, they have more luck with the weather than I have. Let's hope that they, at least, will have clear skies tonight!


  1. Association of Amateur Astronomers? What a heartless translation! It's the 'Association of Starfriends' :-)

    BTW: I was faster, see: Lunar Eclipse. Yeah, I've tried their page and created a column called 'Next to Leading Order'. I have vaguely in mind to recycle some of our nicer posts from the last year. E.g. the ones about extra dimensions, black holes, neutrinos - maybe with some updates (esp. I wonder what's the matter with MiniBoone, anybody knows gossip?)

  2. It's 22:50 in germany and I have just a look out of my window- half of the moon just disapeared.
    I hope no clouds in the nexr 30 minutes and I will see the total eclipse.
    Best Mum

  3. Hi Bee, it's slowly been turning brown for the last hour.

    Should be a full eclipse over Cambridge in the bext few minutes.
    Beautiful clear sky, bright stars all around.
    Have a nice weekend!

  4. Greetings,

    I wonder about the geometric cone of the shadow.

    Is the shape of the shadow purely caused by geometry alone - or does it tell something about the nature of light. (like photons trying to fill the "void" (of photons))



  5. It was a very nice thing to watch here in Carinthia (Austria). We were lucky and had perfect weather. Some neighbors of ours even had some fireworks to celebrate this event.

    Klaus, just draw it on a piece of paper. Make the sun a big circle and the earth a smaller one. Then draw the straight lines, that are tangential to both circles. You'll find out, that there are four of them. Now you can also see, why there are two "types of shadows". You can not draw a straight line touching the sun and any point inside the cone behind the earth without touching the earth. I don't know whether "touching" is the right expression here. That's Earth Umbra and the whole trick.

  6. Hi Klaus,

    interesting question. I guess it tells you among other things that photons don't interact with each other (at least at tree level), but from the reddish/orange color you can tell that they do interact (scatter) with dust in the atmosphere though. This interaction depends on the photon's energy (frequency), and the fact that the low frequency (red) photon's are scattered less tells you something about the cross-section and it's dependence on the frequency. Well. That's the first thing that comes into my mind.

    Hi J├╝rgen,

    you guys are sooo lucky tonight in Europe! I just talked to a friend on the phone (in Germany), and he said they too had all clear sky and an amazing view (except that he lives in a big city and there's too many light emission). Greetings to Austria,


  7. Dear Stefan, Your English is excellent, but sometimes you make charming mistakes. I think you meant to say _Live_ Reporting, not _Life_ Reporting.

    When I first read that, I thought you were reporting on a new life form on the Moon.. Now that would be news!

  8. Dear amara,

    oops, thanks for the hint... - no live reporting about life on the moon ;-)..

    BTW, here in Frankfurt I've had good luck with the weather in the end: the clouds went away around 10:00 UT, and nearly the whole eclipse was visible :-)

    Best, stefan

  9. Speaking of life on the Moon, I've gotta say, it can only be described as mind-blowing to be standing on the Moon while the Sun-Earth-Moon system was undergoing an eclipse...

    In fact, folks on the Moon would not only experience an intense red glow beneath their feet, but simultaneously see a most brilliant red ring of fire around Earth...

    Oh sure, during Earth's lunar eclipse, Earthling oughta be sheerly amazed to watch the Moon take on a ruddy appearance. In contrast though, Lunarians should be utterly awe-struck to witness such a surreal sight!

  10. This was one of those typical situations for us. It had been perfectly clear all day, though extremely windy. We drove up to a mountain lookout to watch the eclipsed moonrise, but of course, just before time for the moonrise a large cloud system blew in to block the view to the east. But we stayed for a while and finally the clouds broke for us to see the moon when the eclipse was about a third finished. Ironically, after we drove back home the sky to the east was completely clear again on the horizon. Oh well.

  11. Hi Bee,

    I saw the ending phase of the eclipse from Tulum... It was nice, since I had forgotten about it, and upon casually seeing a faint crescent low in the evening sky instead of a fullish moon I had a heartstroke!

    Hmmm I could make a post of it actually...



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