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The Sky This Week, 2011 June 7 - 14

The Honey Moon approaches, and let the summer begin!

Supernova SN 2011dh in Messier 51, discovered 2011 May 31
Imaged with the USNO Flagstaff Station's 1.3-meter reflector, 2011 June 7 UT
U.S. Naval Observatory image courtesy of Dr. Marc Murison

The Moon brightens the evening sky as she waxes toward her Full phase, which occurs on the 15th at 2:14 pm Eastern Daylight Time. June’s Full Moon is variously known as the Rose Moon, Flower Moon, Strawberry Moon, or Honey Moon. Each of these names derive from the characteristic appearance of June’s Full Moon, which occurs as Luna reaches her southernmost declination of the year. Since her altitude is quite low for temperate Northern Hemisphere observers her light passes through more of the Earth’s atmosphere which preferentially scatters blue light. Luna’s face therefore takes on a warm cast, not because she appears to be more red, but rather because she appears less blue! This year the Honey Moon happens to produce a total lunar eclipse, which means that for much of the Eastern Hemisphere she will appear to be a very deep coppery-red at some point on the night of the 15th – 16th. Unfortunately those of us living in the USA will be shut out from seeing any part of this eclipse. We won’t experience another total lunar eclipse here in the Washington, DC area until April 15th, 2014. Luna begins the week as a waxing crescent about seven degrees south of the bright star Regulus. From the 9th through the 11th the Moon passes south of golden Saturn and the blue-tinged star Spica. On the night of the 14th look for the ruddy star Antares about five degrees to the right of the Moon’s nearly-full disc.

By the end of the week we enter the two-week "season" of phenomena associated with the summer solstice, which falls on June 21st. Due to the complex interplay between modern timekeeping and the elliptical nature of Earth’s orbit we’ll experience the year’s earliest sunrise on the 14th. Here in Washington this occurs at 5:42 am EDT. Old Sol will then gradually begin to rise a tad later thereafter, but the time of sunset is still moving slightly later each night. We won’t experience the latest sunset until the 28th, when the Sun will go down at 8:38 pm. Sandwiched in between is the solstice itself, and it is on this day that we experience the longest duration of daylight for the year with the Sun above the horizon for 14 hours and 55 minutes. Summer is almost "officially" upon us!

Apart from the Moon, just about the only other bright things to find in the urban sky right now are a handful of bright stars and the warm glow of Saturn. The ringed planet reaches the second stationary point in this year’s apparition on the 14th, halting his westward motion against the background stars before gradually resuming his eastward trek around the sky. Many people have remarked about the planet’s apparent faint "companion" that’s been visible to the unaided eye on very clear nights lately. This purported companion is actually a third-magnitude star known as Porrima, one of the most interesting binary stars in the heavens. Although they appear separated by only 1.4 of a degree on the plane of the sky, Porrima is located at a distance of some 39 light-years from the Sun. Saturn, on the other hand, is only about 77 light-minutes away! Take advantage of the late evening twilight hours to scan Saturn in a telescope. Often some of the best planetary viewing conditions occur on sultry summer nights when the air seems heavy and still.

If you’re up to watch the earliest sunrise, look toward the east for the bright glimmers of Jupiter and Venus. Jupiter should be very easy to spot in the gathering twilight some 15 degrees above the horizon, but Venus will be much trickier. At half an hour before sunrise she is only five degrees up from the horizon, and on hazy mornings her brilliant glow may not pierce the dense air lingering just off the ground. However, if the horizon is clear she should be quite easy to spot. Between the two bright planets is the much fainter ruddy glow of Mars, which you might be able to track down in binoculars. The red planet will slowly wend his way into the evening sky by the end of the year. His next opposition won’t occur until March of 2012.

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