LUNAR CALENDAR FOR AUGUST 2013
Photo by: ME – Information on this month’s Perseids Meteor Shower as well as links and a video below.
AUGUST 1st (Thu) – Entering the month the Moon is 23.6 days old in its 29.53 day Synodic Cycle and 25% illuminated in its waning crescent phase.
AUGUST 2nd – 11th (Fri to following Sun) – As of the 2nd we are on the verge of the New Moon (Lunation 1121), this week presents nights that are the absolute BEST nights to get out and observe Deep Sky Objects (DSOs) because you won’t have to look through the spotlight that is the Moon. Night skies without the Moon are significantly more productive for viewing and photography ANY night sky object (besides the Moon itself of course). For the lucky ones, this week offers the amazing spectacle of the extreme Crescent Moon, both waning in the east & waxing in the west.
AUGUST 2nd (Fri) – The Moon is at its Greatest Northern Declination of +20.1 degrees.
AUGUST 3rd (Sat) – APOGEE MOON occurs at 0854 UTC (0453 EDT) where the Moon is at its furthest point from Earth in its current orbit and will be subtending at 29’ arc minutes from a distance of 405,833km (252,174mi).
AUGUST 6th (Tue) – New Moon (LUNATION 1121) occurs at 2152 UTC (1752 EDT).
AUGUST 6th (Tue) – LATITUDINAL LIBRATION (see definition below) is at MAXIMUM (+6.6 degrees).
AUGUST 11th (Sun) – 13th (Tue) The PERSEIDS METEOR SHOWER reaches peak phase the night of Aug 11 through sunrise of Aug 12. The night of the 13th should be pretty good as well. One of the more prominent showers of the year, the Perseids are also a northern hemisphere favorite because of the warm summer nights. The radiant point of the Perseids is the constellation Perseus in the north and this year you can expect anywhere from 50-75 per hour. The Moon will be around 20% illuminated for peak nights as it begins growing into its first quarter phase and will be setting just after midnight. The parent body for this shower is Comet 109P/Swift-Tuttle. DON’T FORGET – You can still see many of the Delta Aquarids which peaked in late July. Streaks from the south will be primarily Delta Aquarids while streaks from the north will be primarily Perseids.
One last point to make on meteor showers; Do you know why meteor shower viewing is best just before sunrise? If you view the solar system from the top, planets orbit the Sun in a counter clockwise motion, we also rotate in a counter clockwise motion. That means just before sunrise the Earth is pointed in the direction of travel of the Earth itself and meteors are mere “bugs hitting the windshield” of Spaceship Earth. For information on the major Meteor Showers of 2013 check my write up: https://danspace77.com/2013-meteor-showers/
AUGUST 12th (Mon) – LONGITUDINAL LIBRATION (see definition below) is at MINIMUM (-6.0 degrees).
AUGUST 13th (Tue) – LUNAR-X also known as the PURBACH or WERNER CROSS is scheduled to reach a fully formed “X” at 1844 UTC (1444 EDT) which means the Americas, Europe and Africa will still be in daylight conditions. Asia and the islands will have a great view though (Weather permitting). The Lunar-X is the big, more prominent brother to the Curtiss Cross. This “X” is created by the effect of shadows along rims and ridges of craters LaCaille, Blanchinus and Purbach. The “X” formations occur along the Terminator (where “day” meets “night” along the Moon).
AUGUST 13th (Tues) – The Moon is at Ascending Node.
AUGUST 14th (Wed) – FIRST QUARTER MOON is the Moon watchers paradise. Occurring at 1056 UTC (0656 EDT), First Quarter Moons and the waxing crescent phase leading up to it offer some of the most visually stunning views the Moon has to offer. Most of us will take the beautiful curves, valleys and shadows of a 1st Quarter Moon over a Full Moon ANY day.
AUGUST 16th (Fri) – The Moon is at its Greatest Southern Declination of -19.5 degrees.
AUGUST 19th (Mon) – PERIGEE MOON occurs at 0126 UTC (2126 EDT on the 18th) and is when the Moon is at its closest point to Earth in its orbit. It will be subtending at 33’arc minutes from a distance of 362,265 km (225,101 mi).
AUGUST 19th (Mon) – LATITUDINAL LIBRATION (see definition below) is at MINIMUM of (-6.5 degrees).
AUGUST 21st (Weds) – The Full Moon will occur at 0145 UTC (2145 EDT on the 2oth). THE FULL STURGEON MOON = The fishing tribes are given credit for the naming of this Moon, since Sturgeon, a large fish of the Great Lakes as well as other major bodies of water were most readily caught during this month. Other names this month are Full Red Moon, Green Corn Moon and the Grain Moon.
AUGUST 24th (Sat) – LONGITUDINAL LIBRATION (see definition below) is at a MAXIMUM of (+6.9 degrees).
AUGUST 26th (Mon) – The Moon is at Descending Node.
AUGUST 28th (Wed) – Last Quarter Moon occurs this month at 0935 UTC (0535 EDT).
AUGUST 29th (Thu) – The CURTISS CROSS, an effect of shadows along craters Gambart and Parry which create an “X” shaped illumination will occur at 2152 UTC (1752 EDT). This month it will be hidden from the U.S. and points west due to daylight while Europe and points east should have no trouble viewing it.
AUGUST 29th (Thu) – The Moon is once again at its Greatest Northern Declination of +19.5 degrees.
AUGUST 30th (Fri) – APOGEE MOON occurs once again this month at 2346 UTC (1946 EDT) where the Moon is at its furthest point from Earth in its current orbit and will be subtending at 29’ arc minutes from a distance of 404,883km (251,582mi).
AUGUST 31st (Sat) – Leaving the month the Moon is 25 days old in its 29.53 day Lunar Cycle and 23% illuminated in its waning crescent phase.
***Definition of LIBRATION (basically) – Is an oscillation of an orbiting body relative to another. OK, so…We know the Earth/Moon system is tidally locked so we always see the same side of the moon. Due to libration, we ACTUALLY see about 60% of the Moon instead of what you may intuitively think of as a 50% measurement. That’s because the Moon oscillates slightly as it rotates and orbits Earth. So, on occasion and with a keen eye we can see a little further “around the corner” north, south, east and west on the moon by a couple degrees.
***SUBTENDING Explained – Definition: The angle formed by an object at a given external point. The moon subtends an angle of approximately 0.54° (32 arc minutes) to an observer on the Earth. Of course, the moon’s orbit is not constant or exactly circular, so this varies a little, but not by very much.
If you hold up your thumb at arm’s length, you can easily cover the full moon. This means your thumb subtends a larger angle to your eye at arm’s length than the moon does at 380,000 kilometers.
In general, the closer you are to a particular object the larger that subtending angle.
Moon phase and libration for 2013: