The August Sky

Paul Curtin

The northern summer features the Summer Triangle, composed of Vega in the west (see July Eye on the Sky), Deneb in the northeast, and Altair in the southeast. Deneb is the brightest star in Cygnus, a striking constellation embedded in the summer Milky Way. The most prominent pattern in Cygnus is often called the Northern Cross. This is a great region for scanning with binoculars or rich field telescopes. In dark skies one can see the dark lane that runs south from Deneb. See Kepple and Sanner for finder charts.

South of Cygnus is tiny Sagitta, which does indeed look like an arrow flying eastwards. Look for the globular cluster M71 along the shaft of the arrow. Northwest of Sagitta we find Brocchi’s Cluster, known to some as the "Coat hanger." This compact object, though catalogued as Collinder 399, is not in fact a true cluster but rather a line of sight phenomenon. Nonetheless it is a charming sight to the naked eye or in binoculars.

Following the Milky Way south we find Aquila, the Eagle. Its brightest star, Altair, is flanked to the south by beta aquilae and to the north by gamma aquilae. Scan the entire length of this constellation with binoculars to observe the dark rift that runs through it. With the exception of a sprinkling of planetary nebulae, the dark rift is the sole deep sky object of interest in this region. The lack of open and globular clusters is unusual for a constellation set fast in the Milky Way.

Further south is Sgittarius, the treasure trove of the northern summer sky. Sagittarius abounds in deep-sky objects of all types. Its western sector has some of the best known emission/reflection nebulae, such as M17 (the Omega Nebula), M20 (the Trifid Nebula), M8 (the Lagoon Nebula) and a slew of bright star clusters such as M18, M21, M23, M24, and M25. In the east, Sagittarius contains a wealth of globular clusters. The center of our galaxy lies in this region, thus the bright star fields and dark lanes of Sagittarius are without rival.

South of Sagittarius one finds a paler, inverted version of the Northern Crown. Not surprisingly, this is known as Corona Australis, which, though small and faint, is host to some interesting star clouds and dark lanes.

Far southern observers get their last good glimpse of the winter Milky Way as Ara moves to the west. Look for NGC 6397, a very bright globular cluster embedded in the star clouds of northeastern Ara. In Telescopium and Pavo one begins to pick up faint galaxies of interest to those with large aperture telescopes.

The Planets in August

Mercury is a morning object after mid month.

Venus sets soon after the sun but, given a clear western horizon it should still be easy to locate.

Mars, moves into Aries this month. Remember to begin observing Mars as soon as you can if you wish to be in top form for this years opposition.

Jupiter sets early now and will be too low in the sky for useful observation.

Saturn is an early morning object, slowly moving out of dawn twilight.

Bibliography

Archinal, B. A., Hynes, S. J., Star Clusters, Richmond, Virginia: Willman-Bell, 2003.

Bone, Neil, Mars Observers Guide, Buffalo: Firefly Books, 2003.

Burnham, Robert Jr., Burnham's Celestial Handbook, New York: Dover, 1978.

Dobbins, T., Parker, D., Capen, C., Introduction to Observing and photographing the Solar System, Richmond, Virginia: Willman-Bell, 1988.

Gupta, R. (ed.), Observers Handbook 2005, Toronto: University of Toronto Press, 2004.

Kepple, G. R., Sanner, G. W., The Night Sky Observers Guide, Richmond, Virginia: Willman-Bell, 1999.

Tirion, W., Rappaport, B., Remaklus, W., Uranometria Deep Sky Atlas, Richmond, Virginia: Willman-Bell, 2000.

Price, F., The Planet Observer's Handbook, Cambridge: Cambridge University Press, 1994.

Webb, T. W., Celestial Objects for Common Telescopes, New York: Dover, 1962.