On Saturday afternoon at 3 p.m. EST, the moon was at its closest point to the Earth in 2011: a distance of 221,565 miles away.
At its peak, the supermoon of March was 14 percent larger and 30 percent brighter than lesser full moons (when the moon is at its farthest from Earth). But to the casual observer, it may be hard to tell the difference.
The moon has not been in a position to appear this large since March 1993.
In December 2008, there was a near-supermoon when the moon turned full four hours away from its perigee – the point in its orbit that is closest to Earth. But this month, the full moon and perigee are just under one hour apart, promising spectacular views, depending on local conditions.
Although a full moon theoretically lasts just a moment, that moment is imperceptible to ordinary observation.
During the day or so before and after, most will speak of seeing the nearly full moon as "full," with the actual shaded area of the lunar surface being so narrow – and changing in apparent width so slowly – that it is hard for the naked eye to tell whether it's present, or which side it is.
Supermoon making waves
In addition, the near coincidence of Saturday’s full moon with perigee will result in a dramatically large range of high and low ocean tides.
The highest tides will not, however, coincide with the perigee moon but will actually lag by up to a few days depending on the specific coastal location. For example, in Wilmington, N.C., the highest tide (5.3 feet) will be attained at 11:21 p.m. EDT on March 20.
In New York City, high water (5.9 feet) at The Battery comes at 10:49 p.m. EDT on March 21, while at Boston Harbor, a peak tide height of 12.2 feet comes at 1:31 a.m. EDT on March 22, almost 2 1/2 after perigee.
But then, to those living on the shores near the Bay of Fundy in eastern Canada, the 10- to 20-foot (3- to 6-meter) increase in the vertical tidal range makes it obvious when the Moon lies near perigee, clear skies or cloudy.
Any coastal storm at sea around this time will almost certainly aggravate coastal flooding problems.
Such an extreme tide is known as a perigean spring tide, the word spring being derived from the German springen – to "spring up," and is not, as is often mistaken, a reference to the spring season.
At its peak, the supermoon of March was 14 percent larger and 30 percent brighter than lesser full moons (when the moon is at its farthest from Earth). But to the casual observer, it may be hard to tell the difference.
The moon has not been in a position to appear this large since March 1993.
In December 2008, there was a near-supermoon when the moon turned full four hours away from its perigee – the point in its orbit that is closest to Earth. But this month, the full moon and perigee are just under one hour apart, promising spectacular views, depending on local conditions.
Although a full moon theoretically lasts just a moment, that moment is imperceptible to ordinary observation.
During the day or so before and after, most will speak of seeing the nearly full moon as "full," with the actual shaded area of the lunar surface being so narrow – and changing in apparent width so slowly – that it is hard for the naked eye to tell whether it's present, or which side it is.
Supermoon making waves
In addition, the near coincidence of Saturday’s full moon with perigee will result in a dramatically large range of high and low ocean tides.
The highest tides will not, however, coincide with the perigee moon but will actually lag by up to a few days depending on the specific coastal location. For example, in Wilmington, N.C., the highest tide (5.3 feet) will be attained at 11:21 p.m. EDT on March 20.
In New York City, high water (5.9 feet) at The Battery comes at 10:49 p.m. EDT on March 21, while at Boston Harbor, a peak tide height of 12.2 feet comes at 1:31 a.m. EDT on March 22, almost 2 1/2 after perigee.
But then, to those living on the shores near the Bay of Fundy in eastern Canada, the 10- to 20-foot (3- to 6-meter) increase in the vertical tidal range makes it obvious when the Moon lies near perigee, clear skies or cloudy.
Any coastal storm at sea around this time will almost certainly aggravate coastal flooding problems.
Such an extreme tide is known as a perigean spring tide, the word spring being derived from the German springen – to "spring up," and is not, as is often mistaken, a reference to the spring season.
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