Sunday, December 26, 2010

Partial solar eclipse on January 4th

The eclipse season continues, as the Moon's nodes--the intersection line of the Moon's orbital plane and the Earth's orbital plane--continue to point in the direction of the Sun and anti-Sun. After the winter solstice lunar eclipse Europe, Northern Africa, and the Middle East will get a partial solar eclipse on January 4th. The maximum eclipse reaches nearly 86% in Scandinavia, although I wouldn't really trust a low-altitude solar eclipse at the Arctic Circle this time of year to be likely visible.

Since we know the Moon's orbital plane right now, we can extrapolate to the appearance of the Moon in upcoming months and phases. We know that the first and third quarter Moons will be either higher or lower away from the ecliptic, since at new the moon was obviously at the ecliptic (to produce the eclipse). So we need one other piece of information to give us the appearance of the Moon in the sky: is the node ascending or descending? Recall the Moon passing Jupiter about two weeks ago.
Was it above or below Jupiter in the sky?

Sadly, I had to check via a planetarium program because I couldn't remember. It passed above Jupiter. So the node is ascending, and the First Quarter Moon in January will be higher than usual in the sky and the Third Quarter Moon lower (but keep in mind only in deviation from the ecliptic, not in absolute elevation in the sky). In three months (aka March-April) the full Moon will be lower in the sky than usual and rise and set further south than normal.

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