Why this supermoon is the stand-out
WTOP's Megan Cloherty reports
WASHINGTON - It is a busy time in the sky as a supermoon Sunday will compete with the ongoing Perseid meteor shower for top billing with sky watchers.
This Sunday the full moon will be 30 percent brighter and 14 percent larger than normal full moons and it will be the closest the moon will be to the Earth for the entire year of 2014. This is the second in a series of three consecutive supermoons, the last one occurred on July 12 and the next one will be on Sept. 9. Last year also had three consecutive supermoons.
The moon is full at 2:09 p.m. EDT and reaches perigee, or its closest point to the Earth for the current lunar cycle, just 26 minutes earlier. At its closest approach the moon will be 221,765 miles away, just shy of the closest it can ever be to Earth - 221,457 miles. Being at perigee is the key to a full moon being a "supermoon" - a non-astronomical term that has now become part of our culture. Simply put a supermoon is really a full moon at perigee.
It will be difficult to visually judge the larger apparent size of this Sunday's supermoon but I think moon lovers like me can detect the greater brightness. Just go outside after the sun sets and face the southeast to see the moon rise. This is when the full moon is at its best. Mariners and beachgoers will also have higher and lower than normal tides due to the moon being closer to Earth.
Supermoon Sunday and the following nights, when the almost full moon is in the sky all night, will dampen this year's Perseid meteor shower. Each year during August the cometary debris from Comet Swift-Tuttle intersects the Earth and produces a wonderful display of falling or shooting stars - meteors. These bits of comet dust, about the size of a grain of sand, hit our atmosphere at 140,000 miles per hour!
With a dark sky site and no moon present, sky watchers can count on seeing up to 100 meteors an hour. This year the bright and almost full moon will reduce the number to a predicted 30 to 40 per hour. These will be bright meteors and the Perseids produce a lot of fireballs - meteors that are brighter than Venus. NASA's meteor monitoring stations have reported a number of bright Perseid fireballs in the past few days.
The Perseids will peak on the night of Aug. 12 to 13 but it is worthwhile to get out any clear night after 11 p.m. local time and especially the hours before dawn to look for them. The best place to watch the Perseids is somewhere free of city lights that offers a clear view of the whole sky. Being comfortable is key to watching the shower.
I will give my next "Let's Talk About Space at Shenandoah National Park" presentation on the Chesapeake Bay Impact Crater at 9 p.m., Aug. 12 at Big Meadows Lodge, Shenandoah National Park. Afterwards, if it is clear, we will meet at Big Meadows to watch the Perseids.
If it is cloudy where you live on the night of Aug, 12, you can still enjoy the Perseids by tuning in to NASA's live Internet chat and live stream (weather permitting).
You can also listen in via space radar to hear the Perseids, a favorite activity of mine, anytime up until the shower ends sometime after Aug. 13. This includes day time hours as well.
Here's to clear skies and hope to see you at Big Meadows!
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