A rare celestial sight

Published Aug 11, 2014

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Durban - Earth’s closest celestial neighbour, the moon, on Sunday night came by on its closest visit this year, much to the delight of astronomy enthusiasts – and hopeless romantics.

When it’s so close, and therefore appearing so large, it’s referred to as the “supermoon”, explained Brad Inggs, chief executive of Durban-based space technology company, Orbital Horizon.

The company made local headlines in 2011, when it partnered with American company, Xcor Aerospace, and began offering trips into space in a new suborbital spaceship – at a cost of nearly R1-million a person.

At the time he said the company wanted to use the capital to fund interplanetary research and look into new lunar projects.

Inggs said the distance between Earth and the moon varied, but the average distance was about 382 900km.

“When the moon is at ‘perigee’, that means it is at its closest range to the Earth (‘apogee’ is at its furthest). Supermoon comes when perigee happens at the same time as the full moon phase.”

He added that at the closest approach, the moon would be about 356 896km away, appearing roughly 16 percent larger and 30 percent brighter.

“Some of us have driven this distance in our cars.”

The moon was 358 260km away on July 12 and will be even closer – 358 389km away – on September 9.

Inggs said it was unique when the moon reached perigee minutes before it actually reached its full phase. Similar timing like last night, he added, would not happen again until 2034.

It would have been a “perfect” opportunity to plan a romantic evening, he said.

When asked if the event would have any effect on any earthly process, Inggs said: “The moon does control our ocean tides. If anything, effects we will see just include a few inches in tidal rise.”

He added jokingly: “Perhaps (it may result in) some odd human behaviour like howling at the moon or romantic acts.”

University of KwaZulu-Natal physics professor, Jonathan Sievers, said that the term supermoon actually came from an astrologer and so was not particularly important to astronomers.

“We will see it from Durban, but you would never notice it unless you had taken detailed pictures of other full moons to compare it to,” he said.

“The moon’s orbit stays fixed relative to the Earth, so we get supermoons every time the Earth’s orbit around the sun lines up with the moon’s closest approach. This happens every year around this time, so effectively all full moons during July and August are supermoons.”

He added that one interesting fact was that when the moon was exactly full, it appeared significantly brighter than even one day before or after.

“This has nothing to do with the supermoon, but instead comes from how dust at the surface of the moon reflects light.”

Online astronomy magazine, Sky and Telescope, dismissed the event, saying there were five supermoons predicted for the year: January 1, January 30, July 12, August 10 (Sunday) and one to come on September 9, rendering it insignificant.

Daily News

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