The October Sky

Paul Curtin

This October column features the return of the red planet. Observers in the north have an excellent opportunity to catch Mars at opposition. Though Mars will not be as close as in 2003, the viewing possibilities will be far superior due to decreased atmospheric interference. Mars will dominate the night sky until the end of the year.

Observers in Europe, Africa, the Middle East and some of Asia will be able to observe an annular solar eclipse on 3 October. A partial lunar eclipse will be visible in parts of western North America, Central America, Asia and Australia on 17 October. See Gupta for details.

Although October generally turns our view from our own galaxy to objects beyond, our northernmost constellation, with its star fields, clusters and gaseous nebulae, seems to be a holdout from the northern
summer. Cepheus is a house-shaped figure northeast of Cygnus. Its southern section is a fine area for wide-field scanning. Look for the numerous open clusters embedded in this section of the Milky Way. See Jones or Kepple and Sanner for finder charts and descriptions. South of Cepheus, hanging from the Milky Way, is Lacerta. Northern Lacerta is also of interest in terms of star fields and open clusters but the southern portion is quite barren.

The Great Square of Pegasus is the first prominent object east of the Milky Way. Pegasus contains few deep sky objects other than a few rather faint galaxies. The one exception to this is the distinctive globular cluster M15, found by following a line from theta to epsilon Pegasi (i.e. the southwestern leg of the horse) westwards. Of greater interest is Aquarius, which boasts a range of deep-sky objects.
Beginning in the southwest corner, northeast of theta Capricorni in the center of Capricornus, is the bright planetary NGC 7009, the Saturn Nebula. Look for the globular cluster M72 and the open cluster M73 to the southwest. M2 is a bright globular due north of beta Aquarii. Scattered throughout central and eastern Aquarius are a number of faint galaxies that can be a challenge to locate In the far southern reaches of Aquarius we find NGC 7293, the Helix Nebula. This is a large planetary with low surface brightness but worth seeking out. Far northern observers may lose out due to atmospheric disturbance.

To the south we find Piscis Austrinus and Grus. The dazzling Fomalhaut (alpha Piscis Austrini) stands out in this region otherwise noteworthy only for a sprinkling of faint galaxies. Closer to the pole the Small Magellanic Cloud, a member of our Local Group of galaxies, and 47 Tucanae, an exceptionally bright globular cluster, are objects that warrant careful and repeated observation.

The Planets in October

Mercury is a fine evening object for southern observers. Observers in the north must wait until December to view this elusive planet.

Venus is an evening object this month. It comes close to Antares on the evening of 16 October.

Mars reaches its maximum apparent disk diameter at the end of the month. Look for a blazing red object hovering on the Aries/Taurus border.

Jupiter is very hard to find in the early evening sky.

Saturn, in Cancer, is a morning object.

Bibliography

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

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

Jones, K. G. (ed.), Webb Society Deep-Sky Observers Handbook, Volume. 3, Hillside, NJ: Enslow Publishers, 1980.

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.