The July Sky

Paul Curtin

In the north, look for Draco, whose head is composed of a quadrilateral sometimes called the "Lozenge." From the Lozenge, follow the string of stars northeast and then due west towards Ursa Major. Although it boasts many double stars, Draco is rather lacking in deep sky objects. One notable exception is the planetary nebula NGC 6543, due north of the Lozenge. See Kepple for finder charts.

East of Corona Borealis is Hercules with its characteristic asterism known as the Keystone. M13, a bright globular cluster, can be found one quarter of the way between the western stars of the Keystone. M92 is another globular located almost halfway between the Keystone and the Lozenge in Draco.

Northern summer is announced by the ascent of the blazing white Vega (alpha Lyrae). The small parallelogram just south and east of Vega is the small part of Lyra. Note the fainter star northeast of Vega: this is epsilon Lyrae. Small telescopes show epsilon to be a double star, greater magnification reveals that each member of this pair is itself double. Sweep slowly between the southernmost stars of the parallelogram for the ghostly smoke ring of M57, the Ring Nebula. Harder to find (lacking as it does such distinct guide stars as those flanking M57) is M56, a very compact globular cluster near the southern border of Cygnus. To find it, follow the line formed by the southern stars of the parallelogram halfway to Albireo (beta cygni) at the base of the Northern Cross.

South of Lyra and Hercules is the large kite shaped constellation Ophiuchus, a region rich in open and globular clusters. In many respects Ophiuchus is similar to Auriga in the winter sky: an attractive open frame containing a great ranger of deep sky objects. Though not as crowded as the star clouds to the east, this region richly rewards those sweep slowly at low power.

Due south of Ophiuchus we find the distinctive shape of Scorpius, a constellation rich in deep sky objects. Antares (alpha Scorpii) is a red star that outshines all others in this part of the sky. Nestled close to Antares are two globular clusters, M4 and NGC 6144, with M80 further to the northwest. The Milky Way due east of Antares merits close scrutiny. Embedded in this region are a number of globular clusters, the most prominent being M19, M62 and NGC 6441. There are also numerous star clusters such as M6 and M7 not far from the ‘stinger’ of the Scorpion. In binoculars or rich field telescopes the star fields of Scorpius are truly stunning.

Southern observers can investigate the Milky Way in Norma. To the east, in Ara, the globular cluster NGC 6397 is a very fine object. Western Pavo and Octans have little of interest for small and mid-sized telescopes.

The Planets in July

Mercury is low in the east at dawn. This is a good month to glimpse the elusive planet.

Venus is an evening object but may be difficult to find this month.

Mars, is in Leo. Look for it in the early evening sky near Saturn.

Jupiter, low in the southern sky, can be observed all night.

Saturn is an early evening object in Leo.

Bibliography

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

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

Kelly, P. (ed.), Observers Handbook 2007, Toronto: University of Toronto Press, 2006.

Hynes, S.J., Planetary Nebulae, Richmond, Virginia: Willman-Bell, 1991.

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.

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