The month of August is named after Augustus Caesar and has 31 days like July. Beginning this month we are now exactly halfway into summer and there should be plenty of warm, clear nights that will be getting a little longer to give everyone more time to enjoy and learn about all the wonders that are always taking place above us.

There are some interesting conjunctions this month and this will be a great year to observe the Perseid Meteor Shower because it will peak just before the new moon. One continuing highlight for the whole next year will be constant interesting and exciting data coming in from the New Horizons spacecraft that just had a close encounter with Pluto on July 14.

We are learning many incredible things about this complex and unfamiliar miniature solar system guarding the outpost of our familiar solar system. Complex hydrocarbons have been discovered on Pluto, which is continually leaking nitrogen and methane gas onto its moon Charon, fully half the size of Pluto and located only 12,000 miles from it while locked in a six-day orbit around a common center of gravity like a pair of figure skaters clasping hands.

It is amazing that Pluto has no craters. It is constantly resurfacing itself and exhibits living geology that will help us to better understand how Earth formed. Even Charon has colorful polar regions and giant craters and canyons deeper than our own Grand Canyon. Three of Pluto’s five moons are locked in close rotation to keep them from colliding. Pluto has a similar orange-brown color as Mars, and we arrived at this icy dwarf exactly 50 years to the day of the close encounter of Mariner 4 with Mars in 1965.

From our perspective here on Earth, Venus and Jupiter are getting closer again, but they will both sink below the western horizon well before they will get as close again as they were on the last day of June. Brilliant Venus will be getting very thin and large as it passes through inferior conjunction on Aug. 15. After that it will re-emerge into our morning sky and quickly rise. Look for its thin crescent through binoculars or a telescope early this month before it gets too low to the western horizon.

Eleven years ago and again three years ago, we were privileged to see a very special case of what can happen to Venus at this moment of its inferior conjunction. That is called a transit of Venus and can only happen when the Earth-Venus-Sun plane is perfectly aligned. This happens in an unusual pattern of a pair of transits eight years apart, followed by a long wait of more than 1051/2 years, then another pair of transits eight years apart, and then an even longer gap of 1211/2years. The entire cycle repeats every 243 years. We will have to wait until December 2117 for the next Venus transit at inferior conjunction.

I was fortunate to have been able to see both of these rare transits, especially because I almost missed both of them due to the weather. The June 8, 2004 transit was partially obscured due to heavy early morning fog at our Starfield Observatory in Kennebunk. We enjoyed only tantalizing glimpses of this great event until the fog finally lifted completely just at the critical and most exciting moment as Venus finally emerged from its six-hour-plus journey across the face of the sun. Through a good telescope and solar filter we then witnessed a completely unexpected sight. I saw the subtlety glowing silvery semicircular arc of the dense and poisonous atmosphere of Venus starkly outlined against the blackness of deep space for two full minutes as the planet was rising above the sun. The next transit on June 5, 2012 was not as dramatic but we were very lucky to see it at all since the skies cleared up literally seconds before the great event began after a solid week of rain with no clearing in the forecast.

Jupiter is setting a little earlier each evening. By the sixth of August, the king of the planets will be setting just 45 minutes after sunset and Mercury will be less than 1 degree to the upper right of Jupiter. Also look for Regulus, the brightest star in Leo, close to the pair. You may need binoculars because of the bright twilight.

Now the stage is set for Saturn, the lone bright planet that is visible this month outside of twilight. The ringed planet will end its westward or retrograde motion toward Libra on the second of this month and resume its normal eastward motion back toward the head of Scorpius. Its rings remain open at 24 degrees and it will reach eastern quadrature when it will be 90 degrees east of the sun on the 21st. That is when the shadow of the globe on the rings it at its greatest, which gives the planet an even more three-dimensional view through a telescope.

Mars has returned to the morning sky and now rises about an hour before the sun at the beginning of the month, and it will rise two hours before the sun by the end of the month. Watch as Venus tries to catch up with the red planet toward the end of August. It will not appear to catch Mars until Nov. 3.

This will be a great year for the Perseids not only because the moon will be just before new, but also because Earth should be passing through the debris trail that Comet Swift-Tuttle shed back in 1862, 130 years before its last return in 1992. You should see at least one meteor per minute at its peak.


Aug. 3: On this day in 2004 the Messenger was launched to Mercury.

Aug. 4: On this day in 2007 the Phoenix Mars lander was launched.

Aug. 6: Last quarter moon is at 10:03 p.m. The Curiosity Rover landed on Mars on this day in 2012.

Aug. 8: Mars is just below Castor and Pollux in Gemini is a nearly straight line looking east-northeast 45 minutes before sunrise.

Aug. 12: On this day in 1877 Asaph Hall discovered Deimos, at eight miles across, the smaller of the two moons of Mars. He would discover Phobos just six days later. It is 14 miles across, about the length of Manhattan. The Perseid meteor shower peaks today into tomorrow. This shower usually lasts for several weeks, but it will be at its peak for a couple of days.

Aug. 14: New moon is at 10:53 a.m.

Aug. 16: Look for Mercury in binoculars about 6 degrees to the right of a thin waxing crescent moon.

Aug. 22: First quarter moon is at 3:31 p.m. The moon will be near Saturn tonight one hour after sunset in the south-southwestern sky. On this day in 1963 the X-15 set a world-record altitude record for a winged craft of 354,000 feet, which is 67 miles high, or about where most of the meteors burn up and where the northern lights are the most intense. On this day in 1976, the unmanned Soviet Luna 24 mission returned soil samples from the moon that were 0.1 percent water by mass.

Aug. 25: The Spitzer Space Telescope was launched on this day in 2003. This was the last of a family of four great space telescopes to study the universe in four wavelengths of light. The Hubble Space Telescope was the first. Then the Compton Gamma Ray Observatory was launched in April 1991 and then Chandra in July 1999, looking at the universe in X-rays, and then Spitzer for infrared. The Gamma Ray Observatory was allowed to re-enter our atmosphere back in June 2000.

Aug. 28: On this day in 1789 William Herschel discovered Enceladus, a moon of Saturn. This turned out to be a very dramatic moon that is sending out huge ice plumes into space which reform into a giant icy ring well beyond the visible rings of Saturn.

Aug. 29: Full moon is at 2:35 p.m. This is also called the Green Corn, Grain or Sturgeon Moon.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.

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