Thunder Moon

Another lunar contribution from Gordon, whose contributions are currently keeping this blog alive…

The next full Moon is on Friday morning, July 15, 2010, at 2:39 am EDT.  The Moon will appear full for about 3 days around this time, from Wednesday evening through Saturday morning.

This full Moon has many names:

• For Hindus this is the Guru Full Moon (Guru Purnima) and is celebrated as a time for clearing the mind and honoring the guru or spiritual master.
• Europeans called July’s full Moon the Hay Moon or the Mead Moon.
• The Algonquin tribes in what is now the Eastern US called July’s full Moon the Buck Moon, as July is normally the month when the new antlers of buck deer push out of their foreheads in coatings of velvety fur.  They also called this the Thunder Moon because of July’s frequent thunderstorms.

Since this is the Thunder Moon, a quick note on lightning safety.  Most of the lighting that strikes the ground arcs from the negatively charged bottom of the storm to the ground underneath the storm.  Much more rare is positive lightning, which arcs from the top of a thunderstorm to strike the ground up to eight miles away from the storm.  Positive lightning sometimes strikes areas where the sky is mostly clear (hence the term “bolt out of the blue”).

Because it arcs across a greater distance it tends to be 5 to 10 times more powerful that regular ground strikes.  Though positive lightning is rare (less than
5% of all lightning strikes), the lack of warning combined with its greater power tends to make it more dangerous.  A good rule to follow is if you can hear the thunder, you can be struck by the lightning.  As a bicycle commuter I am well aware that the inch or so of rubber tire between my metal bicycle and the ground will make little difference to a bolt that can arc across miles of air from the top of a thunderstorm to the ground.

Be safe!

As to other sky events between now and the full Moon in August:

• Mercury joins Saturn in the evening sky after sunset.  Try looking to the west-northwest near the horizon about 45 minutes after sunset (about 9:15 pm EDT for the Washington, DC area).  Mercury reaches its greatest elongation (largest angle away from the Sun as seen from the Earth) on Wednesday, July 20, 2011.
• If you are in a dark location with a clear sky on July 31, or August 1, 2011, try looking for the Capricornid Meteor shower.  Although this shower only produces 10 to 15 meteors per hour (i.e., on average one every 5 or 6 minutes), some of them can be bright fireballs.  The best time to look is after midnight.
• If you have a good telescope, on Thursday, August 11, 2011, Neptune will be at opposition, fully lit and at its closest to the Earth for this year.

The full Moon after next will be on Saturday, August 13, 2011.

As usual, celebratory attire (e.g., Aloha shirts, bow ties, etc.) is encouraged in honor of the full Moon, watch out for lightning, and consider setting aside a little time to clear the mind.