The Internet is buzzing with rumors that this month’s extreme SuperMoon might have caused last week’s earthquake and tsunami in Japan and the Pacific Ocean. But folks at the Farmer’s Alamanac note that, ”Most astronomers dismiss this line of thinking, though, arguing that the 2,000-mile difference is minimal in the grand scheme of things – less than 1 percent of the Moon’s total distance from the Earth – and unlikely to cause much disruption on Earth, beyond the usual proxigean spring tide.”
They note that proxigean spring tides are usually stronger when the Moon is new. “So the conventional wisdom is that the upcoming event will result only in slightly higher than normal spring tides.”
This month’s full moon, which rises on the eve of the first day of Spring, is historically known as the Full Worm Moon.
“As the temperature begins to warm and the ground begins to thaw, earthworm casts appear, heralding the return of the robins,” the Farmer’s Almanac notes. “The more northern tribes knew this Moon as the Full Crow Moon, when the cawing of crows signaled the end of winter; or the Full Crust Moon, because the snow cover becomes crusted from thawing by day and freezing at night. The Full Sap Moon, marking the time of tapping maple trees, is another variation. To the settlers, it was also known as the Lenten Moon, and was considered to be the last full Moon of winter.”
Whatever you call it, the moon that rises this Saturday will be the largest full moon in nearly 20 years, and could appear 14 percent larger and 30 percent brighter than usual.
This is because of the shape of the Moon’s orbit, which is oval in shape: as the moon orbits the Earth each month, it reaches a point furthest from the Earth, called apogee, and a point closest to the Earth, called perigee. An extreme SuperMoon occurs when the Moon is close to 100 percent perigee.
Or, as the Almanac notes, “When the Moon is full, it sits exactly on the opposite side of the Earth from the Sun. When it’s new, it sits between the Earth and the Sun. In both cases, the gravitational pull from the Moon and the Sun combine to create larger than normal tides, called “spring tides.” And when the Moon is also at perigee, the effect is magnified into what is called a “proxigean spring tide.”
This week’s extreme SuperMoon is the fourth since 2005, and the largest and brightest since 1992. The Moon will be 221,567 miles away, just a tiny bit closer than its average closest distance of about 223,500 (the Moon’s average distance from the Earth is 235,000, and its average furthest distance is 248,000 miles).
“Even though this particular full Moon is larger than normal and at its closest point to the Earth, it is unlikely to cause much disruption on Earth, beyond the usual proxigean spring tide. These tides are usually stronger when the Moon is new than when it’s full, so the conventional wisdom is that the upcoming event will result only in slightly higher than normal spring tides.”
Now, whether we’ll be able to see in between all the rain is another matter entirely.