SKY HAPPENINGS

The Sky for November 2013
By Faylene Roth

The Summer Triangle (western horizon) bequeaths the overhead skies to the Great Square of Pegasus—centerpiece of autumn’s night sky—accompanied by Andromeda, Aries, Pisces, and Aquarius. The Big Dipper (Ursa Major) seems to touch ground on the northern horizon. Taurus, Orion, and Gemini crest the eastern horizon, hinting at the brilliant winter sky to come.

DAYLENGTH
Evening activities by natural light end on Sunday, November 3, at 2:00am when standard time replaces daylight saving time. Move clocks back one hour. The total period of daylight continues to diminish as the ecliptic (sun’s path across the sky) moves southward. By month’s end we lose 52 minutes of light. The three periods of twilight seem more abrupt this month as sunrises and sunsets scatter less light over the bulge of the earth’s equator. At sunset the sun drops an additional six degrees below the horizon with each 30-minute period of twilight—civil, nautical, astronomical. Skies are completely dark (moonlight excepted) at the end of astronomical twilight, one and one-half hours after sunset. The reverse progression applies to dawn.

MOON HAPPENINGS
November 3 – New Moon occurs at 5:50am.
November 10 –First Quarter Moon sets soon after midnight.
November 17–Full Moon occurs 8:16am and rises at 5:23pm.
November 25 – Last Quarter Moon rises near midnight.
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)

METEOR EVENTS
Light meteor activity continues throughout November but the Taurids Meteor Shower promises the best viewing opportunity of the month on the night of November 4/5. A new moon period provides dark skies. The Taurids radiant—in Taurus—rises around 8:00pm and is overhead around 3:00am when viewing is best. On November 16/17 the Leonids Meteor Shower—a stronger event—must compete with a full moon throughout the night. Leo—the radiant for this shower—rises around 1:00am and is not overhead until after sunrise. The full moon, however, will be low on the western horizon by sunrise so the pre-twilight period from 4:00am to 6:00am should reveal the brightest of the meteors. Expect 10-15 meteors per hour. (While looking for the Leonid meteors, take the opportunity to scan the eastern sky for Comet Ison.) Remember that most meteors have traveled away from their radiant by the time they enter the Earth’s atmosphere, so they may appear in any region of the sky.

COMET ISON
Stay tuned to http://www.universetoday.com/104818/comet-ison-a-viewing-guide-from-now-to-perihelion/ for the latest news on Comet Ison’s swing around the sun. The comet is expected to reach naked-eye visibility sometime during the month. On November 5 it passes from Leo into Virgo. On November 18 it passes within 0.38° of Virgo’s brightest star Spica. (Spica rises in the eastern sky about an hour before astronomical twilight begins to brighten the morning sky. Find Spica by following the arc of the Big Dipper’s handle down towards the east to red-orange Arcturus. Continue the arc to blue-tinged Spica.) On November 22 Ison passes into Libra and reaches perihelion (closest point) with the sun on November 28. Perihelion to the sun marks the make or break point for comet viewers. If the sun’s gravitational pull breaks the comet to pieces, it fizzles into obscurity. If Ison survives the pass intact, then let’s hope that it flares to a brightness that rivals Venus, if not the full moon, as earlier predicted. The Universe Today website posts a calendar and maps to assist in finding the comet.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. The width of the little finger approximates 1.5 ̊. Middle, ring, and little finger touching represent about 5 ̊. The width of a fist is about 10 ̊. The fist with the thumb extended at a right angle equals 15 ̊. The hand stretched from thumb to little finger approximates 20 ̊-25 ̊. The diameter of both the full moon and the sun spans only 0.5 ̊. Adjust for the size of your hand.

Primary Sources: USGS; U.S. Naval Observatory; Your Sky at http://www.fourmilab.ch/yoursky/
To find out when the space shuttle and International Space Station are visible from your location, go to: http://spaceflight.nasa.gov/realdata/sightings/index.html and click on Sighting Opportunities.

VISIBLE PLANETS

Jupiter rises before midnight on November 1, but jumps quickly forward into the evening sky after daylight saving time ends on November 3. By month’s end look for it between 8:00pm and 9:00pm on the eastern horizon in Gemini. (Magnitude -2.3)

Mars brightens slightly this month as it moves across the base of Leo. On November 27 the small red planet moves into Virgo. (Magnitude +1.3)

Venus sets about one hour after astronomical twilight darkens the night sky. On November 6 it appears near a waxing crescent moon. Venus remains in Sagittarius (low on the western horizon) throughout the month and brightens slightly as it moves closer to the sun. (Magnitude -4.6)

Note: Apparent magnitude values range from -4 to +6 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.

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 sky from astronomical twilight to midnight. As the night and month progresses, the constellations shift toward the northwest. The celestial equator is measured in hours (h). The ecliptic is measured in degrees.