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Gettin' Busy with the Moon
Observing >
Get a calendar in one hand, a pencil in the other, and let's mark off some November dates of celestial interest.
Tonight you can catch a glimpse of the just-past-full Moon of November which actually had the moniker "the Frosty Moon" --- seriously. But for a couple hours Saturday night it was more like Frosty the No-Moon (no relation to Frosty the Snowman).
Yes,
our nearly full Moon this evening --- technically a waning gibbous ---
comes, not coincidentally, right on the heels of Saturday's lunar eclipse.
You will recall that a lunar eclipse happens as the Moon slowly passes
through Earth's long, fat shadow on exactly the opposite side of Earth
as the sun.
The Moon goes around us once a month but doesn't always go through our shadow giving us a lunar eclipse. Nor does it pass directly in front of the Sun every month providing us a solar eclipse. Its orbit is slightly tilted so it only has a chance of "getting in the way" every six months or so, during what is called "eclipse seasons." The Moon is in such an alignment now.
Presently our orbiting friend is on his way to the other side of Earth to get between us and the Sun, to cast its shadow on us --- a celestial form of "getting even." In two weeks, on the 23rd, it will finally arrive to vengefully block out the sun's light! But alas! its very skinny shadow will dot only the icy cold southern reaches of the Great White South --- Antarctica. Scientists there, joined by some penguins and eclipse fanatics with a lot of time and money, will be freezing together in the shadow of the Moon.
On the same date, the 23rd, the Moon coincidentally will also be at its closest approach to the Earth, a point called perigee. This combination of being on the same side as the sun and being so near us at the same time will affect those of us who live near the ocean. How?
When
the Moon and Sun are on the same side like this their combined gravitational
forces can pull our oceans up toward them resulting in fairly high tides.
Because it is so close compared to the sun, the Moon actually exerts a
greater pull than the sun even though it is so tiny, which explains why
it is the major influence in tides. Moreover, when the Moon is at perigee,
as it will be then, its pull is even greater and the tides even higher.
On the nights of the 16th through the 19th (but peaking on the night of 17th/18th) we have the annual Leonid meteor shower. And as usual, it is hard to tell what it will be like. Will we have hundreds of meteors an hour or just a few? Will there be giant fireballs, or just barely-lit shooting stars? It's impossible to tell, but the great mystery of these events is part of the fun of it all, and is what gets the meteor mobs all fired up on these nights. Go out after midnight for your best chance of seeing them.
And finally for those who take astrology --- as opposed to astronomy --- seriously, consider the following: On Saturday the 22nd, the Sun enters the astrological sign of Sagittarius. The problem? The sun is actually still in Libra headed for Scorpius. It won't be in Sagittarius until next month. And, interestingly enough, on the 30th the Sun enters the constellation Ophiuchus. Ophiu-who?
There is no sign in Ophiuchus in astrology. Oops.
Until next time, clear skies!
Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.
Posted by Administrator at 2003.11. 8 01:02 PM | Comments (0)
