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Sky Happenings October 2008
Moab UT (at City Hall)
38O34’ N Latitude 109O33’ W Longitude
4048 ft - 1234 m




The Sky for October 2008
By Faylene Roth


Sunrise and Sunset Times for
October 2008

LOCAL STAR COUNT
WabiSabi invites you to enjoy the night sky and participate in an international star count to raise awareness of light pollution. Join me at Ken’s Lake at 7:00pm on Saturday, November 1, to learn to identify the constellations in the night sky and to conduct a local star survey for the Great Worldwide Star Count. If skies are cloudy or weather inclement, we will reschedule the event for Sunday, November 2, at the same time. Bring the star chart from this page and a flashlight covered with a red shield or a small brown paper bag. Dress warmly and bring a blanket or chair if desired. Meet at the parking lot beside the lake. This is a free event for all ages. Call 259-9114 or 259-4743 to RSVP or for more information.

The period of daylight continues to decrease rapidly this month. We lose 72 minutes by month’s end. Civil twilight provides adequate light for most activities for one-half hour after sunset. Nautical twilight continues for another 30 minutes with colors and shapes still apparent. Astronomical twilight continues for another half hour. It is marked by the lack of color and visible detail. The reverse progression applies to dawn. Sunrise and sunset are calculated for a flat horizon. Actual times may vary depending upon the terrain.

MOON HAPPENINGS
On the evening of October 2 look for Venus next to a waxing crescent moon, low in the southwestern sky. On October 6 the first quarter moon appears a little higher in the sky just below Jupiter. Full Moon occurs on October 14. On October 16 and 17 a waning gibbous moon rises with the Pleiades star cluster about an hour after sunset. Look for Saturn and and a thin waning crescent moon in the early dawn on the morning of October 24. The bright star Regulus (constellation Leo) will be above the moon. New Moon occurs on October 28. On the evening of October 31, a waxing crescent moon again appears with Venus in the southwestern sky.

GREAT WORLDWIDE STAR COUNT
Join this international effort, as a citizen scientist, to count the number of stars that can be seen from different localities around the world. Participants in the Northern Hemisphere will estimate the number of stars visible around the constellation Cygnus, the Swan. Observations can be made anytime from October 20 through November 3. Locate Cygnus on this month’s star chart then look for it overhead between 8:30pm and 9:00pm. The GWWSC website provides easy-to-use magnitude charts for estimating the number of stars you see. Determine latitude and longitude for your observation site with a GPS unit, the Geocoder link on the GWWSC website, or a topo map. The star count is sponsored by the University Corporation for Atmospheric Research in Boulder, Colorado, to raise awareness of the effect of light pollution on the night sky. Go to their website at http://www.starcount.org/ for directions and a reporting form.

METEOR EVENTS
The Orionid Meteor Shower peaks on the night of October 21. Meteor activity increases as the radiant point of the meteor activity rises. Look to the east after midnight in the vicinity of Orion for 10-15 meteors per hour. Midnight is the best time for viewing this meteor shower, because a third quarter moon rises soon after. The activity from this shower extends from October 20-25.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. Adjust for the size of your hand. The width of the little finger approximates 1.5 degrees. Middle, ring, and little finger touching represent about 5 degrees. The width of a fist is about 10 degrees. The hand stretched from thumb to little finger equals 20 degrees. The diameter of both the full moon and the sun spans only 0.5 degree.

VISIBLE PLANETS
Jupiter - Follow the Milky Way across the sky from north to south to find Jupiter in the upper left region of Sagittarius. Shining at magnitude -2.1, it is the most prominent planet in the evening sky. Jupiter appears a little lower in the western sky each night. By the end of the month, it is nearly as low in the sky as Venus.
Mars - Shining at magnitude +1.6, Mars is the faintest of the visible planets right now. It sets about 45 minutes after sunset during the first few weeks of October then disappears into the glare of the sun for the rest of the month.
Mercury - By mid-month, Mercury is rising about one and one-half hours before the sun. Look Eastward just as twilight breaks. Mercury is difficult to see because the light of the rising sun overpowers it. The best opportunity for viewing is the morning of October 22 when it reaches its greatest elongation (distance from the sun). Mercury will appear below Saturn, but will be brighter with a magnitude of -0.5.
Saturn - Find Saturn in the early morning twilight in the eastern sky, shining at magnitude +0.7. In early October it rises about two hours before sunrise. Saturn will appear higher in the sky each morning before sunrise. By month’s end, it is rising four hours before the sun.
Venus - Look low in the southwestern sky in the evening twilight for Venus. At magnitude -3.7 it is still the brightest of the planets. As the month progresses, it appears a little higher in the sky each evening and moves southward. It is unlikely you will see it unless you find a high viewpoint with a clear view of the southwestern horizon.

Note: Apparent magnitude values range from -4 to +5 for most planets and visible stars. The lower the value the brighter the object. A decrease of 1.0 magnitude is 2.5 times brighter.

Primary Sources: USGS, U.S. Naval Observatory, http://www.fourmilab.ch/yoursky/

MAJOR CONSTELLATIONS this MONTH

Overhead
Aquila
Cygnus
Lyra

Northward
Cassiopeia
Cepheus
Draco
Ursa Major
Ursa Minor

Eastward
Andromeda
Aries
Pegasus
Perseus
Pisces
Triangulum

Southward
Aquarius
Capricornus
Cetus
Sagittarius

Westward
Bootes
Corona Borealis
Hercules
Ophiucus


As twilight fades, Scorpius rests on the southwestern horizon with the Summer Triangle overhead and the Great Square of Pegasus to its east. Perseus, Andromeda, and Pisces line the eastern horizon.

Hold the star chart high above your head and match the compass directions to the direction you are facing.
Adjust the star chart by orienting Ursa Major (Big Dipper) to match its position in the sky.

The star chart approximates the night sky from astronomical twilight to midnight. As the night and the month progress, the constellations will shift toward the northwest.

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