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The Night Sky of August
Dr. Wayne Wooten
Professor of Astronomy
For August the first quarter moon is on August
7th. The waxing gibbous moon passes two
degrees north of Jupiter on August 9th. On the
morning of the 12th, the moon will occult
(cover) Saturn, but only for observers west of
us. When they set about 3 AM locally, the moon
will still be to the lower right of Saturn. If
you are still up then, you will see the peak
of the Perseid meteor shower, coming out of
Perseus, almost overhead then. After moonset,
you may get about a meteor a minute before
dawn comes. The full moon, the Green Corn
Moon, will be on August 15th. The last quarter
moon will be on August 23rd, and the moon will
be new 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 2019; 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 2018 sky from the Hubble
Space Telescope website at: http://hubblesite.org.
Sky & Telescope has highlights at http://www.skyandtelescope.com
for observing the sky each week of the month.
Mercury, Venus, and Mars are all too close to
the sun for good viewing in August. Jupiter is
still well placed for viewing in the southwest
in Ophiuchus at sunset, just north of Antares
in Scorpius. The Great Red Spot is easy to
spot with small telescope, as are the four
larger moons. Much more distant, fainter
Saturn is in eastern Sagittarius, in the south
at sunset. Enjoy the rings, now 24 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 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. To the south is 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 2019 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. In the same binocular field
just north of the Lagoon is M-20, the Trifid
Nebula. Just east of the pair 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.
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