March 3, 2007, Lunar Eclipse
Published on Mar 1, 2007 at 4:30 pm.
2 Comments.
Filed under eclipses, skywatching.
If you live in the right place, go out and look for the lunar eclipse this Saturday night.
Lunar eclipses happen when the Moon passes into the Earth’s shadow. They often play second behind the solar eclipses, when the Moon passes in front of the Sun, and that is a shame. They are really quite interesting in their own right. But, the mass media normally seems to concentrate on the solar eclipses. That might be somewhat understandable, though, since it is more dramatic if the Sun were to be blotted out than the Moon being blotted out. Furthermore, as I said in my earlier post, the Moon normally doesn’t get totally blotted out, even during a total lunar eclipse. Generally light scattered and refracted through Earth’s atmosphere still illuminates the Moon to a degree (though not nearly as much as if they Sun were shining directly on it).
Lunar eclipses and solar eclipses happen with similar frequency. However, total lunar eclipses happen more often than total solar eclipses (the Earth’s shadow is bigger than the Moon’s shadow). Furthermore, everyone on the night side of the Earth can see the lunar eclipse, while only a select few in just the right spot can see a solar eclipse. Solar eclipses, from beginning to end can last no more than about two hours (and only a few minutes of that can be total, the rest is partial). Lunar eclipses can last last almost 3 hours 45 minutes, with the total portion up to about 1 hour 45 minutes long. This gives far more people a chance to see a lunar eclipse. But, even so, you still have to be in the right place.
This graphic, from Fred Espenak’s Eclipse Page at NASA’s Goddard Spaceflight Center, shows the visibility of the eclipse. The entire event is visible in Africa and Europe. However, for those of us in the Americas, the Moon will be rising with various stages of the eclipse in progress. Most of Asia will see the Moon setting as the eclipse is underway.
To make sense of these you need to know what some of the notations mean. P1 marks the time that the Moon first enters the penumbra of Earth’s shadow. That’s the lighter outer shadow, where the Earth only partially blocks the Sun. P4 marks the time that the Moon finally leaves the penumbra. But, for most people, this is not anything that really concerns them. The penumbra has only a small effect, and it isn’t the dramatic eclipse that people generally want to see. That occurs when the Moon enters the umbra, which is the darkest portion of the Earth’s shadow, where the Earth completely blocks the Sun from directly shining on the Moon. When you say “lunar eclipse,” the Moon passing into the Earth’s umbra is what nearly everyone immediately thinks of. The lines marked on the map U1 and U4 show where the Moon first enters the umbra, and there it completely leaves the umbra. From the map you can see that only the westernmost portion of Australia sees this, but nearly all of Asia does. In the United States and Canada, you have to be east of the Rocky Mountains to see the Moon be in the umbra for any time at all. Only the eastern most portion of Brazil is able to see the Moon enter the umbra in all of the Americas. U2 marks when the Moon is completely in the umbra, and U3 marks the the point where the Moon finally emerges from the umbra. From the map, you can see that the U3 line runs close to the Mississippi River in the United States. If you live east of that, then you can see the Moon rise totally eclipsed, and then coming out of eclipse. If you live west of that, then the Moon is already coming out of eclipse when it rises. I am in Texas, so the Moon will already be coming out of eclipse when it rises Saturday night. But, weather permitting, I will still go outside to look at it!
You can find even more particulars for the event on the following graphic. It will be hard to read reduced like this, so click on it for a full scale view.
-Astroprof
(Moon Image credit: Doug Murray, posted at Science@NASA, maps courtesy of Fred Espenak, NASA/GSFC)
A Ler…-- Rastos de Luz on March 2, 2007 at 7:51 am: 1
[…] “Total Lunar Eclipse: March 3rd 2007“, no Astronomy Blog. Ainda sobre este assunto, “March 3, 2007, Lunar Eclipse“, no Astroprof’s Page. Pois é, é já amanhã, vamos ver se o tempo ajuda. Mais pormenores sobre o evento, incluindo sessões de observação e webcasts na secção “Destaque“; […]
Mark Smith on March 2, 2007 at 3:19 pm: 2
Getting ready for the eclipse in the Uk current weather predictions are for clear sky’s but we will see.
Mark