Big tides
Published on Nov 24, 2007 at 5:53 pm.
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Filed under Earth, moon.
Today is Full Moon. This Full Moon also falls on the same day that the Moon reaches perigee (the closest point in its elliptical orbit to the Earth). That means high tides. I’ve blogged about tides twice before: here and here. You can read those postings to find more about tides.
Basically, the Moon’s gravity causes the tides. But, the Sun also can cause tides. So, whenever you have Full Moon or New Moon, the tides are all lined up, and you get unusually high high tides and unusually low low tides. That condition is called spring tide. Today is spring tide because we have a Full Moon.
But, that is not all. The Moon has an elliptical orbit. It reached its closest point in its orbit to Earth just this morning. When the Moon is closer, the tides are correspondingly slightly stronger. So, that makes this spring tide situation a bit more extreme, even, than normal. Oh, but that still isn’t everything! The Earth moves around the Sun in an elliptical orbit, too. Earth will be the closest that it gets to the Sun on January 3, 2008 (something that we call perihelion). Just as the Moon being at perigee makes the lunar tides stronger, the Earth being at perihelion results in stronger solar tides. So, with Earth’s perihelion in just over a month, the solar tides are also rather strong.
You put all of this together, and today expect to see extra heavy tides. You can read my earlier posting for addition information about how all of this works.
So, if you live near the coast, you can go and look at the tides roll in tonight.
-Astroprof
