Saturday, June 22, 2013

Look for tonight's Supermoon


Beginning tonight night and heading into tomorrow morning, the full moon becomes a “supermoon,” being closer than any other full moon of the year. When it is at its nearest one hour after sunrise on Sunday, the moon appears 7% wider and 15% larger than the average full moon. Its distance shrinks to 222,000 miles, some 18,000 miles less than that of the average full moon. 

Reports are circulating on its unusual brightness in the sky and its unusual closeness to our planet. Curious skywatchers should take the hyperbole with more than a grain of moon dust. 

While the June 22/23 full moon will be the closest of the year, it will not necessarily be the brightest. Saturday’s full moon lies in the same low region of the sky where the December sun shines. Therefore, it won’t reach a high sky position, but it will trace a shallow arc beginning in the southeast thirty minutes before sunset, rising low in the south, then ending in the southwest fifteen minutes after sunrise. 

Summer haze may substantially diminish the brightness of tonight’s supermoon, causing it to be dimmer than the year’s smallest full moon which occurs on December 17. That cold moon, while being 21% smaller, climbs much higher in the December night reaching the same height as June’s noonday sun. It’s light cuts through much less atmospheric muck, appearing glaringly bright, possibly brighter than this weekend’s supermoon.

Moonrise in the Roanoke area today is about 8 p.m. Any judgement about its brightness shouldn’t be made until after 10 p.m. when it has risen appreciably above the south-southeastern horizon. If it is cloudy, the next supermoon can be seen next year on August 10.

Such is our view from Earth...

No comments: