Not so big a difference –supermoon vs normal full moon
The media has been full of stories about tonight’s “supermoon,” which is the largest in 68 years. Supermoon is the popular term for what astronomers call a moon perigee–syzygy. This means that the moon is at its closest point to earth in its elliptical orbit and that the earth, moon, and sun are in alignment, resulting in a full moon. The last time the moon was this close to the earth was in 1948, and the next comparable supermoon will be in 2032.
Also associated with the supermoon is the so-called “king tide.” Tides normally vary with the phase of the moon, being higher or lower on days where the moon is full or there is a new moon. The king tide associated with a supermoon, called a perigean spring tide, is generally a few inches higher than a normal spring tide.
Is the supermoon a big deal? Opinions vary widely.
The supermoon is about 15% larger and about 16% brighter than the average full moon, which may or may not be noticeable to the average observer. Hayden Planetarium director Neil deGrasse Tyson commented, “if you have a 16 inch pizza, would you call that a super pizza compared with a 15 inch pizza?”
Likewise, the king tide is typically only a few inches higher than a normal spring tide. Typically, tides can vary by a few inches above or below the expected heights due to storms and wind direction. In those low-lying areas where the king tides cause flooding, the real culprit may be rising sea-levels more than the tides.
If you are on the East Coast of the United States, and you want to see the supermoon tonight, you may be out of luck when you step outside. Much of the East Coast sky is expected to be obscured by cloud cover this evening. If you really want to see the supermoon, however, you can catch it on-line here.
Source SPACE.com: All about our solar system, outer space and exploration
WATCH OUT FOR REPORTS FROM VENICE AND FLORIDA
https://weather.com/news/news/supermoon-high-tides-coastal-flooding
One is glad to see this professional explanation and the correct tidal term used for this rare event.
Here in South Florida there is near hysteria from the media over flooding on streets in Miami Beach and other coastal towns. Reporters wade through seawater talking and dragging cameras and microphones.
Of course if these cities had built proper seawalls in relation to the tides all this could have been avoided generations ago.
As with the hurricanes the amount of misinformation and incorrect terms given out on both Spanish and English (American version!!) language stations is amazing.
Good Watch.
New Bedford MA Port Authority. Closing Hurricane Barrier at high tide times for a few days!!. Really!!
WAL
Amazed by the discrepancy between the numbers. Yours: 15% larger and 16% brighter. Space.com: 14% larger and 30% brighter. A swift look out my window favours yours.
There are various numbers floating around. The source I used is based on the differential between the average full moon size and the supermoon, whereas others compare the smallest full moon, the mini-moon, with the supermoon.