Supermoon: Moon to be closest to Earth

On the May 6, 2012, the moon will be closest to the earth than it will be on any other night in 2012 and will appear significantly larger. This phenomenon, called Supermoon, this year 2012 it coincides with ‘Buddha Purnima’. On May 6 at 9.05 pm, the distance between the earth and the moon will be 3,56,955 km, the nearest in 2012, and the angular size of the moon will be 0.5515 degrees.

It is very exciting to note that the moon will set at western horizon a few minutes before sunrise and then it will rise again on the same evening about an hour after the sunset.

On November 28, 2012 the moon will be the farthest from the earth this year and the distance between the two will be 4,06,349 km. Thus, the full moon of May 6, 2012 will be about 11% larger than the full moon of November 28, 2012.

What is Supermoon?

It is the coincidence of a Full Moon (or a new moon) with the closest approach the Moon makes to the Earth on its elliptical orbit, or perigee, resulting to the technical name for a ‘Supermoon’ of the Perigee-Syzygy of the Earth-Moon-Sun system.

The name SuperMoon was coined by astrologer Richard Nolle in 1979, defined as:

“…a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth.”

What is ‘Perigee-Syzygy’?

The term supermoon is not widely accepted or used within the astronomy or scientific community, who prefer the term ‘Perigee-Syzygy’.

• Perigee: It is the point at which the Moon is closest in its orbit to the Earth.
• Syzygy: It is a full or new moon, when the Earth, the Moon and the Sun are aligned nearly in a straight line.
• Supermoon = Prigree + Syzygy, although they do not perfectly coincide each time.

Thus a Supermoon can be regarded as a combination of the two, although they do not perfectly coincide each time. Syzygy may occur within a maximum of 12 hours from perigee during a supermoon, and 1 hour from perigee during an extreme Supermoon.

What is the affect of Supermoon on Tides?

The relationship of the Moon with both oceanic and crustal tides has led to claims that the Supermoon phenomenon may be linked with heightened risk of events such as earthquakes and volcanic eruptions. Nevertheless, the confirmation of such a link is broadly held to be doubtful.

The mutual effect of the Sun and Moon on the Earth’s oceans, the tide, is biggest when the Moon is either new or full. At lunar perigee the tidal force is even stronger, resulting in larger high and low tides on average, but even at its most powerful this force is still weak causing tidal differences of inches at most.

As the tidal force follows an inverse-cube law, that force is 18% greater than average. However, since the real amplitude of tides differs all over the world, this a direct effect might not be lead by it.

Month: Current Affairs - May, 2012