For August the full moon, the Thunder Moon, is on August 1st. It passes two degrees south of Saturn on August 3rd. The last quarter moon is three degrees north of Jupiter and Uranus on August 8th, with all three rising about midnight. The slender waning crescent moon will offer little problem for observing the Perseid meteor showers on the weekend of August 12th. Expect a meteor a minute under dark skies, with most arriving after midnight, and the radiant in Perseus climbing higher in the dawn hours. The new moon is on August 16th, and passes the planets Mercury and Mars in twilight on August 18th, a great photo op. the moon is first quarter on August 24th, and a "Blue Moon" (the second full, moon of a calendar month) on August 30th, when it lies two degrees south of Saturn.
Mercury is at its best evening appearance on August 9th, at greatest eastern elongation 27 degrees east of the Sun in the evening twilight. Venus lies between us and the Sun at inferior conjunction on August 13th, but will become visible just before sunrise in the dawn sky by the first week of September. Mars too is lost in the sun’s glare this month. Jupiter is close to Uranus in morning sky in Aries, but will be rising in the NE by 10 PM at month’s end. Saturn is at opposition, rising in SE in Aquarius at sunset on August 27th; compared to last year, the rings this year are closing, and appear much thinner in the telescope.
With climate change, more sunlight is being trapped, and the earth for the first time in history had an average global temperature of 69 degrees F for three days in July, the hottest on record. Our star itself is not getting hotter, but it is getting a lot more active, with a peak in sunspots for the whole 21st century reached last week, two years ahead of the predicted solar maximum.
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 2023; 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 2023 sky from the Hubble Space Telescope website at: www.hubblesite.org/explore_astronomy/tonights_sky/. Sky & Telescope has highlights at www.skyandtelescope.com/observing/astronomy-podcasts/ for observing the sky each week of the month.
In the photo note huge Active Region 3633 at upper left; it had just rotated onto the earth facing side of the Sun the day before, but had been tracked from Mars by the camera aboard the Curiosity Rover the previous week, since Mars was 90 degrees east of the Sun and could see half of the Sun still hidden from earth! A true cosmic perspective! The larger spots to the right of it are themselves bigger than Earth!
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. 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; at the other end is Albireo, a fine orange and blue double star well resolved at 20X by almost any smaller scope.
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 2023 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.
