Supermoon biggest of the year

This week's Supermoon was the largest of the year.

This week's Supermoon was the largest of the year.

THIS WEEK'S Supermoon was the largest of the year and it sent Ararat and Stawell sky watchers reaching for their cameras.

The moon has appeared 14 percent clearer and 30 percent closer this month due to the phenomenon.

A supermoon occurs when the moon is at perigee - the point in its orbit that brings it closest to earth - and in its fullest phase.

The perigee between the earth and the moon can vary by as much as the diameter of the Earth during any given month.

In fact, its elliptical orbit sees its distance vary from 363,104 kilometres at perigee to 405,696 kilometres at apogee.

The sun's gravity is actually responsible for pulling the earth and moon into a closer alignment, causing the orbital variation.

For residents the moon appeared brighter and larger in the horizon of the night sky, but that is no more than an optical illusion.

An explanation for its apparent size is that the moon appears much bigger on the horizon because we have trees and buildings to compare it to.

When it is located much higher in the sky, we have nothing to compare it to but the sky itself.

Unusually, this week's supermoon was the fourth for the year, with the last to come on September 9.

A supermoon generally occurs once a year and is viewable in both the Northern and Southern hemispheres.

Supermoons are expected to become smaller in the distant future because the moon itself is slowly propelling itself out of earth's orbit, moving 3.8 centimetres further from earth each year.

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