A supermoon will occur on June 23, when our natural satellite will appear bigger and brighter than normal. In addition, the full Moon will be forming a direct line with the Earth and Sun, increasing the effects of tides.
These events occur every 14 months and are usually accompanied by predictions of natural disasters and tales of strange human behavior. Some people have associated supermoons with earthquakes, tidal waves, floods and more. Even the term "supermoon" was coined not by astronomers, but astrologers.
The actual increased gravitational effects on the Earth from the Moon are not powerful enough to cause such behavior in people or the planet, however, according to most researchers. The increased tides during a supermoon, for instance, are just a couple inches higher than normal. Not everyone agrees, including James O. Berkland, a Glen Ellen, California geologist, who is the subject of the book The Man Who Predicts Earthquakes, by Cal Orey.
"So, we know Earth's gravity triggers moonquakes. I don't think any scientist disputes that. When I learned that, I went to my former [U.S. Geological Survey] colleagues in Menlo Park [California] and pointed out this really exists, so what's so difficult about turning it around?" Berkland asked.
Supermoons occur because of the elliptical shape of the Moon's orbit. Instead of being a perfect circle, the Moon comes 30,000 miles closer to the Earth at its closest point, called a perigee, than it is at it's greatest distance, or apogee. On June 23, our satellite will be 221,824 miles away from our home planet, within 375 miles of the nearest it ever comes. The closest approach to the Earth will be at 7:12 a.m. EDT on the morning of June 23, and will be exactly 100 percent illuminated 20 minutes later.
The Moon will appear slightly larger (about 14 percent larger than when it is at apogee) and brighter than normal on the night of June 22. That effect may be hard to see, however, without a normal Moon with which to compare it.
Although astronomers tend to dislike the term supermoon due to its astrological conotations, the terms "perigee full moon" or "proxigean moon" have never caught on with the general public.
The egg-shaped orbit of the Moon around the Earth changes its orientation, completion one revolution around our planet ever 8.85 years.
The next time the Moon will be as close to the Earth as it will be on June 23 will be in August 2014. In 2022, a similar full supermoon will occur in early summer.
