SKY HAPPENINGS

The Sky for November 2015
By Faylene Roth

The autumn night sky transitions from the brilliance of the summer sky to the brilliance of the winter sky. Three seasonal signs appear across the evening sky: Summer Triangle (three brightest stars of Lyra, Cygnus, and Aquila) in the west; autumn’s Great Square of Pegasus overhead; and the Pleiades star cluster (leading edge of winter’s constellations) in the east.

Twilight extends the period of daylight in three stages at each end of the day. Morning twilight begins with astronomical twilight—about 1-1/2 hours (nearly 2 during summer months) before sunrise—as the eastern horizon brightens. Nautical twilight continues—as the overhead sky turns blue and color returns to the surrounding landscape—for another 30-40 minutes. The final stage—civil twilight—provides adequate light for most outdoor activities for the half hour before the sun crests the horizon. The opposite progression occurs after sunset.

DAYLENGTH
The fall change in daylight saving time is generous. It offers an extra hour for sleep or, if you prefer, an extra hour to catch up on things left undone. This year daylight time ends on Sunday, November 1, when 2:00am MDT falls back to 1:00am MST. The additional hour of evening twilight soon fades as the sun retreats lower below the equator in advance of the approaching winter solstice. By month’s end the period of daylight reduces by 54 minutes.

MOON HAPPENINGS
November 3 – Dark evening skies. A waning last quarter moon rises after midnight.
November 11 – Dark sky period for several days before and after the new moon (10:47am).
November 19 – Bright evening skies. A waxing first quarter moon sets after midnight.
November 25 – Full moon rises at 5:19pm, becomes full at 3:44pm.
(The moon rises later each day—as little as 30 minutes to as much as one hour. Time of moonrise and moonset may also be delayed in mountainous terrain.)
VISIBLE PLANETS
Jupiter – Early risers will observe that Jupiter is the first of three planets to rise in the wee hours before morning twilight. On the morning of November 6 the moon rises about two degrees below Jupiter. Jupiter rises 3-4 minutes earlier each morning which keeps it synchronized with the surrounding stars in Leo. (Magnitude -1.9)
Mars -- Look for the small red orb of Mars—awash in the glare of Venus—as both crest the eastern horizon about one-half hour after Jupiter rises. Mars will overtake Venus on the morning of November 3. The red planet then rises one minute earlier each morning which lets it lag behind Jupiter and move towards Virgo. (Magnitude +1.4)
Venus – Our two nearest neighbor planets spend the first few days of the month within 1 ̊ of one another as they rise around 3:00am. Venus and Mars switch positions in the sky as they pass overhead unseen at 5:30pm on November 2. Venus then rises 1-2 minutes later each day moving deeper into Virgo and a little closer to the horizon each morning. (Magnitude -5.0)

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.

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.

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

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