• The Next Full Moon is the Buck Moon or the Thunder Moon

    A little late again, which is (as always is the case) on me and not on Gordon Johnston, who sends out his once-a-moon updates on stellar and lunar happenings. I’ve missed one or two of the posts, and haven’t written in a while but that will change soon. We’re past proposal season (for me) and so I’ll have a more sane workload going forward.

    Enjoy this full moon, folks – it’s going to be a nice one. 🙂


    The next full Moon is on Sunday morning, June 23, 2013. The Moon will be “opposite” the Sun (in Earth-based longitude) at 7:32 am EDT and will appear full for about 3 days centered on this time, from Friday evening through Monday morning, making this a full Moon weekend. The Moon will reach the point in its orbit closest to the Earth (called perigee) about 1/2 hour before the peak of the full Moon, making this the closest and therefore the brightest full Moon of 2013 (sometimes called a “Super Moon”).

    As the first full Moon of summer, the Algonquin tribes in what is now the Eastern US called this full Moon the Buck Moon, as early Summer is normally 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 early summer’s frequent thunderstorms. Note that some calendars give these names to the full Moon in July, regardless of whether it is the first or second Moon of Summer, but I think the Algonquin tribes would have gone by the seasons rather than the European calendar.

    A new tribe has also given this full Moon a name. This new tribe is geographically scattered but mostly living in the mid-Atlantic region of the United States. This tribe’s language is primarily English, but with a liberal smattering of acronyms and Hawaiian phrases (cheerfully contributed by the former Deputy Manager of the Project). Comprised of people from all backgrounds, this tribe devoted its efforts to the study of the Moon. This tribe calls June’s full Moon the LRO Moon, in honor of the Lunar Reconnaissance Orbiter spacecraft they placed in orbit around the Moon on June 23, 2009. Four years later, LRO continues to orbit and observe the Moon, resulting in major surprises, changing our understanding of the Moon, and leading to new science results published in over 160 peer reviewed papers.
    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 can sometimes strike areas where the sky is 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 usual, suitably celebratory celestial attire (e.g., Aloha shirts, bow ties, etc.) is encouraged in honor of the full Moon. Also, watch out for lightning!

    As to other sky events between now and the full Moon after next, on July 22, 2013:

    Right around the summer solstice is a particularly good time for satellite watching, as the weather is warm so it is comfortable to be outside and many of the satellites are high enough to remain in sunlight as they pass over all night long. Websites like http://www.heavens-above.com/ can provide you with predictions of when satellites will be visible in your area, all you need do is find your city in the database or enter your latitude and longitude.

    Friday, June 21, 2013, at 1:04 am EDT, is the summer solstice, the official start of Summer, so June 21st is the day with the longest daylight period of the year. For the Washington, DC area, sunrise will be at 5:43 am EDT and sunset will be at 8:37 pm EDT. For DC, rounded to the nearest minute, sunset will be at 8:37 pm EDT from Friday, June 21 to Thursday, July 4, 2013, making these the latest sunsets of the year.

    On Friday, June 21, 2013, the bright star appearing to the lower right of the nearly-full Moon (as seen from the northern hemisphere) will be Antares.

    In the early morning (1:54 am) on Sunday, June 30, 2013, the Moon will reach its last quarter, appearing half full.

    In the morning on Friday, July 5, 2013, the Earth will be at aphelion, the farthest away from the Sun we get for the year. Aphelion is at about 1.017 astronomical units, 152,100,000 km, or 94,540,000 miles from Sun. Since the Sun is about 1.7% farther from the Earth than the average Earth-Sun distance and the intensity of light varies as the square of the distance, sunlight a Aphelion is about 3.3% less intense than on average. One of the reasons the seasons in the northern hemisphere are less extreme than in the southern hemisphere is that sunlight is less intense during northern summers and more intense during northern winters.

    Also in the morning on July 5, 2013, around 4:40 am when the sky is just starting to lighten with sunrise, look close to the horizon to the east-northeast to see the waning crescent Moon appear near the bright star Aldebaran.

    The afternoon of Monday, July 8, 2013, will be the new Moon.

    Just after sunset on Thursday, July 11, 2013, very near the western horizon, you may be able to see the thin crescent Moon with the bright star Regulus appearing about 8 degrees to the upper right.

    On Monday, July 15, 2013, the waxing half Moon will appear quite near the bright star Spica. For the Washington, DC area, as the sky darkens with twilight (around 9:42 pm EDT), they will appear about 2 degrees apart. By the time the Moon sets just after midnight, they will have drifted closer to appear about 1/2 degree apart. If you live farther to the west in North America (say on the west coast), they will appear even closer.

    On Tuesday, July 16, 2013, the Moon will appear about 8 degrees from the planet Saturn.

    In the mornings around Monday, July 22, 2013 (around 5 am EDT for the Washington, DC area), low on the horizon in the east-northeast, Mars and Jupiter will appear quite near each other.

    The full Moon after next is on Monday, July 22, 2013.