15 October 2004

Eye on the Sky October/November 2004

Paul Curtin

Upcoming events of note:

- A partial solar eclipse will occur on October 14. It will be visible in northeast Asia. Hawaii, and Alaska.

- A total lunar eclipse, observable from the Americas, West Africa, and Western Europe, will occur the night of October 27/28.

- The Orionid meteor showers peak on October 21 but moonlight may interfere with viewing.

- The Northern Taurid meteor shower peaks on November 12. The moon will not be an issue for these.

- The Leonids peak on November 17. The moon may drown out the fainter members of this famous meteor shower.

The Autumn Sky: The return of the Local Group

The skies of October and November are strikingly poor in bright stars. Southern observers can claim two outstanding exceptions, Fomalhaut and Achernar, but otherwise the night sky presents us with faint and mostly indistinct patterns. In lieu of brightness we are rewarded with subtle asterisms and fascinating deep sky objects. Members of our Local Group are the most prominent objects for both hemispheres.

In the north we begin with Cassiopeia, a large W shaped constellation. Cassiopeia has a large number of star clusters and double stars. Using binoculars, follow the western leg of the W North until you see M52, an open cluster that is impressive in any telescope. Scan along the line between the eastern leg of the W to locate M103, another open cluster. Southeast of the last star on this leg is a field containing a number of open clusters and gaseous nebulae, the brightest of which is Stock 2, a large open cluster.

Continue south and you find the famous Double Cluster in Perseus, NGC 869 and NGC 884. Binoculars are actually best for these as both objects can be seen in one field. Between these objects and the northernmost star in Perseus is Trumpler 2, a much fainter star cluster best seen in large telescopes.

Moving to the west we see the large square that makes up the body of Pegasus. In the southeast we find the globular cluster M15 which is of interest because of its numerous star strings. This is a great object to draw. Successive attempts will demonstrate how the eye becomes more discerning with regular practice.

The V shaped string of stars beginning at the north east star of the great square eastward is Andromeda. Following a line formed by Beta and Mu Andromedae north leads to M31, following it south brings us to M33. These are two great members of the Local Group. M31 is the Andromeda Galaxy and M33 is its cousin in Triangulum. Both are spirals although our line of sight is oblique for M31, nearly perpendicular for M33. Compare these and attempt to draw the spiral arms.

Aries lies due south of Triangulum, it has few objects of interest although one can sweep its fields for double stars. More rewarding is Pisces, just west of Aries. Find the rough circle below Pegasus and follow the line of stars east to Alpha Piscium where another line runs north. Most of the deep sky objects in this region are very faint but a survey of the stars will reveal many doubles of interesting color combination.

South of Pisces is Cetus, composed of two kite-shaped asterisms connected by a straight string of stars. It is the middle star that brings fame to Cetus. This is Omicron Ceti, known as Mira, the Wonderful. Mira fluctuates between magnitude 2 to 10 in roughly 331 days. A care program of magnitude (and spectrum) monitoring can be a rewarding project for those interested in stellar astronomy.

Underneath Cetus is Aquarius. This constellation contains some globular clusters in the west and is sprinkled with faint galaxies. Near the west most star, Epsilon, lie M72, a globular cluster, and NGC 7009, the Saturn Nebula. NGC 7009 is a rather bright planetary nebula but one must be patient in order to glimpse the faint projections on either side. In a faint region in south- central Aquarius we find NGC 7293, the Helix Nebula. This is a large planetary nebula for which Keppler and Sanner suggest using very low powers and a nebula filter.

We move now into the realm of southern skies. The bright star dominating the darkness under Aquarius is Fomalhaut in Piscis Austrinus. Further south are Phoenix and Grus. Phoenix is of little interest although the bright star at the end of Eridanus, Achernar, lights up the southern polar region in November. Grus bears a slight resemblance to Cygnus but lacks the star clouds and nebulae of the northern avian. Tucana boasts two great deep sky objects 47 Tucanae, a very dense, bright globular cluster, and the Small Magellanic Cloud. Both objects merit close study. The thrill of glimpsing nebulae associated with our sister galaxy cannot be overstated.

The planets in November and October

Early risers should look for the morning conjunction of Venus and Jupiter on November 4. Even short exposure photographs of such events can be impressive.

Mercury belongs mostly to southern viewers for now. It puts on a good show in the evening towards the end of October but is even higher after sunset in November. Northerners will have to wait for more favorable views.

Venus is still a very bright morning object throughout October but falls into morning twilight in late November.

Mars is not easy to find in October but moves into Libra at the end of November.

Jupiter rises just before dawn in October, moving into the dark morning sky in November.

Saturn is in Gemini and can be observed after midnight. It begins retrograde motion November 8.

Uranus is in Aquarius and can be observed throughout the night well into November.

Neptune is in central Capricornus and is well placed for observing in October.


Bibliography

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

Gupta, R. (ed.) Observers Handbook 2004. Toronto: University of Toronto Press, 2003.

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

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