SKY GUIDE: This chart represents the sky as it appears over Maine during August. The stars are shown as they appear at 10:30 p.m. early in the month, at 9:30 p.m. at midmonth and at 8:30 p.m. at month’s end. Saturn and Jupiter are shown in their midmonth positions. To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom. Sky Chart prepared by George Ayers.
The month of August is named for Augustus Caesar. We have reached the middle of summer and there are as many interesting highlights in our skies, as always, with one additional and rare bonus – the brightest comet in 23 years.
So get out under the warm skies and enjoy the great beauty always residing far above us, along with this rare primordial visitor from deep space, not to return again for nearly 7,000 years.
Our four brightest planets will be nicely lined up in the morning sky all month by 3 a.m. each morning. Then there will be the usual close conjunctions with the moon, along with the less usual opposition of our largest asteroid, Ceres. The famous Perseid Meteor Shower will happen on the night of the 11th. This is usually the second best shower each year, a close second to the Geminids in December. But the real bonus will be the remaining views of Comet NEOWISE. It will remain visible all month, but will fade from visibility without binoculars by around the middle of August.
Jupiter and Saturn now both rise before sunset, since both are just past opposition, but still nearly at their best for the whole year. They will reach their highest point in our summer sky before midnight.
Mars now rises before midnight and Venus will rise at 2:45 a.m. all month long, becoming the last planet to fill in the quartet of our fellow traveling planets. Notice that Mars is getting visibly brighter and larger each evening as the earth is rapidly catching up with our neighbor in its orbit. The red planet will not begin its retrograde motion until early next month, leading to its close opposition in October.
Our largest and first-discovered asteroid, Ceres, will reach opposition on the 28th in the constellation of Aquarius at 7.7 magnitude, so you would need binoculars. It is 600 miles in diameter, about the size of Texas, and makes up a quarter of all the mass of the millions of asteroids inhabiting the belt between Mars and Jupiter.
The Perseid meteor shower will last for much of this month, but it will peak on Tuesday night the 11th into Wednesday morning. Caused by Comet Swift-Tuttle, this shower lasts for around 20 days, since the material from this comet is spread out over nearly 30 million miles of space. It was last here in 1992. You can expect up to 60 meteors per hour, but the last quarter moon will rise just after midnight to wash out about one third of the meteors after that time, which is when showers usually reach their peak toward morning as the earth is spinning into the source of the meteors after midnight. Look northeast toward Perseus as soon as it gets dark. The radiant of this shower is just below the double cluster in Perseus. Sand grain-sized pieces of this huge comet (it is 16 miles in diameter, one of the largest of all comets) will disintegrate in our upper atmosphere at 36 miles per second, or twice as fast as we are always orbiting the sun.
The “star” of that memorable night was undoubtedly Comet NEOWISE. Discovered by a low-earth orbiting satellite on March 27, it has already brightened more than 1 million times to second magnitude as of the middle of July when I first saw it. It should still be visible without binoculars as it traverses below the Big Dipper into Coma Berenices and Bootes above Virgo for part of this month, even though it is fading fast. Contrary to popular belief, it is only moving about one degree per day westward right now. You can see it as soon as it gets dark until about 11 p.m., when it sinks too low into the western horizon. It will pass right by a globular star cluster named M53 in Coma Berenices on Aug. 7, which will make a great photo op.
NEOWISE stands for Near Earth Orbiting wide field infrared survey explorer. Most comets are discovered by automated ground-based telescopes doing sky surveys and specifically looking for potentially hazardous asteroids that could hit us in the near future. PanSTARRS, LINEAR, SWAN and NEAT are four more of these that have discovered dozens of new comets and asteroids.
The nucleus of NEOWISE is only 3 miles across, but its long tail stretches about 1 million miles, always facing away from the sun. Its coma is about the size of Earth. NEOWISE has two distinct tails, a straight ion tail and a slightly curved dust tail. NEOWISE is the brightest comet to grace our skies since Hale-Bopp in 1997 and only the fifth bright naked-eye comet in the last 50 years, so make sure you try to catch and photograph it before it disappears, not to be seen again for nearly 7,000 years.
AUGUST HIGHLIGHTS
Aug. 1: Maria Mitchell was born in 1818. She was an important American astronomer, naturalist, and educator who also discovered a comet in 1847. The nearly full moon will be close to Jupiter tonight and near Saturn the next night, soon after sunset.
Aug. 3: Full moon is at noon. This is also known as the Grain, Green Corn or Sturgeon moon. The Messenger Spacecraft was launched to Mercury in 2004.
Aug. 4: The Phoenix mission to Mars was launched in 2007.
Aug. 6: The Curiosity Rover landed on Mars in 2012. It is still working well and making lots of new discoveries and taking many great pictures.
Aug. 9: The moon and Mars will be just one degree apart 1 hour before sunrise.
Aug. 11: Last quarter moon is at 12:46 p.m. The Perseid Meteor Shower peaks tonight.
Aug. 15: The moon passes close to Venus in Gemini in the morning sky an hour before sunrise.
Aug. 17: In 2006, Voyager 1 reached 100 A.U. from the sun, which is twice as far out as Pluto orbits on average. Seven years later, it crossed over the heliopause at 123 A.U., where the influence of our sun ends in space.
Aug. 18: New moon is at 10:43 p.m.
Aug. 25: The Spitzer Space Telescope was launched in 2003. That’s the infrared telescope related to the Hubble Space Telescope. The Spitzer just stopped working at the end of January. Last quarter moon is at 1:59 p.m.
Aug. 28: The moon passes near Jupiter for the second time this month.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.
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