Despite the fact that it’s autumn we’re going to have a spring tide next week.
In this case the word “spring” has nothing to do with the season. Instead it means the ocean will be “springing up” in the highest high tide.
Spring tides occur a day or two after a full moon and are highest when the moon is closest to Earth at perigee. On Monday the moon will be full and at its closest perigee since 1948. Watch for nuisance flooding on Tuesday in low-lying coastal communities.
Perigee also makes the moon look larger, an effect called the supermoon. Here are two photos of the full moon in 2007, perigee on the left on October 26, apogee (furthest) on the right on April 3.
The difference is about 30,000 miles. Closer objects look larger. (Duh!)
If you miss this supermoon you’ll have to wait 18 years for it to be this close again.
Read more about November’s supermoon and spring tide at earthsky.org.
(images from Wikimedia Commons. Click on each one to see its original.)