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NIGHT SKY HAPPENINGS

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

The Sky for February 2017
By Faylene Roth

 

Sunrise-Sunset
for February

(The time of sunrise and sunset assumes a flat horizon. Actual time may vary depending upon the landscape.)

DATE

SUNRISE

SUNSET

1

7:23am

5:41pm

2

7:23am

5:42pm

3

7:22am

5:43pm

4

7:21am

5:44pm

5

7:20am

5:45pm

6

7:19am

5:46pm

7

7:18am

5:48pm

8

7:17am

5:49pm

9

7:15am

5:50pm

10

7:14am

5:51pm

11

7:13am

5:52pm

12

7:12am

5:53pm

13

7:11am

5:54pm

14

7:10am

5:55pm

15

7:09am

5:57pm

16

7:07am

5:58pm

17

7:06am

5:59pm

18

7:05am

6:00pm

19

7:03am

6:01pm

20

7:02am

6:02pm

21

7:01am

6:03pm

22

7:00am

6:04pm

23

6:58am

6:05pm

24

6:57am

6:06pm

25

6:55am

6:07pm

26

6:54am

6:08pm

27

6:53am

6:09pm

28

6:51am

6:11pm

The Winter Circle (aka Winter Hexagon) dominates the overhead night sky. On February 7 a waxing gibbous moon sits right in the middle of the seven stars forming the asterism (identifiable group of visible stars that are not a constellation): Capella (Auriga), Aldebaran (Taurus), Rigel (Orion), Sirius (Canis Major), Procyon (Canis Major), Pollux and Castor (Gemini twins). The location of Cancer—one of the faintest constellations—can easily be found on February 9 when the moon sits at its center. Y-shaped Cancer sits on a line about halfway between Pollux (lower Gemini twin) and Regulus (Leo). During February Jupiter can be located after midnight by extending (doubling) this line to Spica (Virgo). Test the darkness of the night sky by looking for the Beehive Cluster in Cancer after midmonth when skies are dark until after midnight. The Beehive (aka Praesepe), an open cluster of about 1,000 young stars (600 million years compared to our sun’s 4.6 billion), is located about 3 ̊ NW of the center star of the Y. Binoculars will reveal individual stars.

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.

VISIBLE PLANETS
Evening (Before Midnight)
Mars – Look for a small bright red orb in the vicinity of Pisces and about 7 ̊ above and left of Venus. Mars sets about one-half hour after Venus. Turquoise Uranus can be located with binoculars or small telescope west of Mars until the last few days of the month when it begins to pass westward of the red planet. (Magnitude +1.3)

Venus – On the first and last days of February Venus, Mars, and a crescent moon will form a triangle above the western horizon during evening twilight. (Magnitude -4.5)

Morning (At Twilight)
Jupiter
– The bright orb overhead by morning twilight is Jupiter. It sits within 3 ̊ above Spica (Virgo). On February 15 a waxing crescent moon forms a triangle with Jupiter and Spica. (Magnitude -2.1)

Saturn – Once Jupiter appears high overhead it is time to watch the southeastern horizon for Saturn’s rising in Ophiucus. By midmonth Saturn rises around 3:30am and is moving into Sagittarius. On February 20 a waning crescent moon hangs about 3.3 ̊ above the planet. (Magnitude +1.4)

MOON HAPPENINGS
February 3 – Waxing first quarter moon lights the evening sky then sets soon after midnight.
February 10 – Full moon (5:33pm) rises at 5:50pm.
February 18 – Dark evening skies return with the waning last quarter moon rising after midnight.
February 26 – New moon (7:58am) yields dark skies for several nights.

(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.)

Twilight is often the best time to look for Venus and Mercury because they frequently rise or set within one-half to one hour of sunrise or sunset. Twilight transitions between night and day in three stages at each end of the day. Morning twilight begins with astronomical twilight as the eastern horizon brightens —about 1-1/2 hours (nearly 2 during summer months) before sunrise when the sun is 18 ̊ below the horizon. Nautical twilight takes over for another 30-40 minutes—as the sun passes 12 ̊ below the horizon and the overhead sky turns blue and color returns to the surrounding landscape. The final stage—civil twilight—begins when the sun ascends to 6 ̊ below the horizon and provides adequate light for most outdoor activities for the half hour before the sun crests the horizon. The opposite progression occurs after sunset. Civil twilight covers the period after sunset during which daytime light quality persists for about one-half hour. Color then fades from the landscape during the 30-40 minute period of nautical twilight during which the overhead sky darkens while the western sky retains color. Astronomical twilight then transitions to night skies that are now darkened along the horizon.

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.

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