Supermoon: lunar close pass brings hard-to-spot spectacle

http://www.guardian.co.uk/science/2012/may/05/supermoon-lunar-close-pass

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The biggest and brightest moon of the year will be seen on Saturday night as it passes closer to the Earth than usual.

Saturday's event is a "supermoon", the closest and therefore the biggest and brightest full moon of the year. The moon will come within about 221,802 miles (357,000km) of Earth, which is about 15,300 miles closer than average.

It will make the moon appear 14% larger than it is when farthest away, said Geoff Chester of the US Naval Observatory. The difference in appearance is so small that "you'd be very hard-pressed to detect that with the unaided eye", he said.

The moon's distance from Earth varies because it follows an elliptical orbit rather than a circular one.

Like any full moon, the supermoon will look bigger when it's on or near the horizon rather than higher in the sky, but that is an optical illusion and not anything to do with the close fly-by.

The supermoon will bring higher tides because of its closeness and its alignment with the sun and Earth, but the effect is predicted to be modest.