The July Sky
Paul Curtin
Jupiter remains an outstanding evening object.
Take the time to observe its moons and cloud structures, as
it will be out of view for the rest of the summer.
Mars returns to the amateur’s realm
this month. Those with large telescopes can begin to search
for surface details. Although Mars will not reach opposition
until November, it is fascinating to watch as week by week
its apparent diameter increases and more features become distinguishable.
Bone has an excellent time-table for this year's opposition.
We will discuss Mars in the next few installments.
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, and 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 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 southeast
halfway to Albireo (beta cygni) at the base of the Northern
Cross.
South of Lyra and Hercules (see "EOS,"
June 2005) 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 range of deep sky objects. Though
not as crowded as the star clouds to the east, this region
richly rewards those who 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 west at dusk but moves
behind the sun in the latter half of July.
Venus is also an early evening object. Look
for it north of Mercury on July 8.
Mars, in Pisces, brightens considerably this
month. It will be a fine morning object throughout the summer.
Jupiter is in Virgo, dominating the western
sky after sunset.
Saturn cannot be seen this month.
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.
Gupta, R. (ed.), Observers Handbook 2005,
Toronto: University of Toronto Press, 2004.
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. 
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