(8/2021) For August the third quarter moon is on August 1st. The New moon is on August 8th, and the waxing crescent passes four degrees north of Venus in western twilight on August 10th. The moon will set well before midnight for ideal viewing conditions for the Perseid Meteor Shower, peaking on the morning of August 12th. Look for perhaps a meteor a minute coming out of the NE after midnight until dawn. The almost full moon passes four degrees south of Saturn on August 20th, and the Thunder Full Moon is four degrees south of Jupiter on August 22nd. The last quarter moon is on August 30th.
While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere skies, about July 31st visit the www.skymaps.com website and download the map for August 2020; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. There is also a video exploring the August 2020 sky from the Hubble Space Telescope website at: www.hubblesite.org. Sky & Telescope has highlights at www.skyandtelescope.com/observing/astronomy-podcasts/ for observing the sky each week of the month.
Mercury is too close to sun for viewing this month, but Venus dominates the western twilight for the rest of this year. Mars was close to Venus in the middle of July, but now is completely lost in the sun’s glare for the next two months. Jupiter and Saturn both reach opposition in the SE this month, with Saturn closest to us on August 2nd, and Jupiter at its best on August 19, with the Full Moon beside it in Aquarius. The Great Red Spot is easy to spot with small telescope, as are the four larger moons. Much more distant, fainter Saturn is to the upper right of Jupiter in Capricornus, just east of brighter Jupiter. Enjoy the rings, now 22 degrees open and tilted toward earth and sun. Look closer and you may see its huge moon Titan, the most earth-like surface geology elsewhere in the solar system!
The Big Dipper rides high in the NW at sunset, but falls lower each evening. Good scouts know to take its leading pointers north to Polaris, the famed Pole Star. For us, it sits 30 degrees (our latitude) high in the north, while the rotating earth beneath makes all the other celestial bodies spin around it from east to west.
Taking the arc in the Dipper’s handle, we "arc" SE to bright orange Arcturus, the brightest star of Spring. Cooler than our yellow Sun, and much poorer in heavy elements, some believe its strange motion reveals it to be an invading star from another smaller galaxy, now colliding with the Milky Way in Sagittarius in the summer sky. Moving almost perpendicular to the plane of our Milky Way, Arcturus was the first star in the sky where its proper motion across the historic sky was noted, by Edmund Halley.
Spike south to Spica, the hot blue star in Virgo. From Spica curve to Corvus the Crow, a four sided grouping. It is above Corvus, in the arms of Virgo, where our large scopes will show members of the Virgo Supercluster, a swarm of over a thousand galaxies about 50 million light years away from us.
Hercules is overhead, with the nice globular cluster M-13 marked on your sky map and visible in binocs. It is faintly visible with the naked eye under dark sky conditions, and among the best binoc objects on the map back page when you download the SkyMap pdf file.
The brightest star of the northern hemisphere, Vega dominates the NE sky. Binoculars reveal the small star just to the NE of Vega, epsilon Lyrae, as a nice double. Larger telescopes at 150X reveal each of this pair is another close double, hence its nickname, the "double double"…a fine sight under steady sky conditions.
Below Vega are the two bright stars of the Summer Triangle; Deneb (to the north) and Altair. Deneb is at the top of the Northern Cross, known as Cygnus the Swan to the Romans. It is one of the most luminous stars in our Galaxy, about 50,000 times brighter than our Sun. It sits atop the Cross, and lies in a region where new stars and born and old stars die literally in front of our eyes! I was lucky enough to discover one such stellar death, Nova Cygni 1975, on August 27, 1975. It peaked at magnitude +1.8, the sixth brightest star of the summer sky, in two days, but faded below naked eye visibility in just two weeks, alas.
A far grander supernova some 15,000 years ago happened SE of the eastern wing of the Swan, epsilon Cygni. The Veil Nebula is faintly visible in big binocs and wide field scopes under very dark skies, but a colorful photographic target. Look to the west at brilliant Venus, and imaging transposing it overhead to the wing of Cygnus; how our ancestors must have been awed by the sudden and perplexing change in the changeless stars! Far more material was blasted out into space than in my nova, and the shock wave from this supernova, now spanning three degrees (six moon diameters), continues expanding at a million miles per hour! What a lovely funeral wreath, with ashes to enrich the Galaxy with life-giving elements. The bright star to the right is 52 Cygni, just visible to naked eye SE of epsilon Cygni.
To the south is the southernmost member of the Triangle, Altair, the brightest star of Aquila the Eagle. If you scan the Milky Way with binocs or a small spotting scope between Altair and Deneb, you will find many nice open star clusters and also a lot of dark nebulae, the dust clouds from which new stars will be born in the future.
To the southeast, Antares is bright in the heart of Scorpius. It appears reddish (its Greek name means rival of Ares or Mars to the Latins) because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturn’s orbit! Just above the tail of the Scorpion are two fine naked eye star clusters, M-7 (discovered by Ptolemy and included in his catalog about 200 AD) and M-6, making one of the best binocular views in the sky. Your binoculars are ideally suited to reveal many fine open star clusters and nebulae in this region of our Galaxy. Get a dark sky site, and use the objects listed on the back of the August 2021 SkyMap printout to guide you to the best deep sky wonders for binoculars and small telescopes.
East of the Scorpion’s tail is the teapot shape of Sagittarius, which marks the heart of our Milky Way galaxy. Looking like a cloud of steam coming out of the teapot’s spout is the fine Lagoon Nebula, M-8, easily visible with the naked eye. Above it is the Trifid Nebula, M-20, another fine and very colorful stellar nursery. Just east of these young star birthplaces is the fine globular cluster M-22, faintly visible to the naked eye and spectacularly resolved in scopes of 8" or larger aperture. Look just east of the top star in the teapot of Sagittarius with binoculars.
