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SKY HAPPENINGS

 

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

The Sky for January 2013
By Faylene Roth



DAYLENGTH

Look forward to an additional 43 minutes of sunlight during January as the earth swings away from its solstice position. By month’s end the period of daylight will exceed 10 hours per day. Later sunsets account for most of the increase in daylength until after the middle of the month when the sun starts to rise earlier each day. Civil twilight contributes adequate light for most outdoor activities for about 30 minutes before sunrise and after sunset. Usable light fades rapidly at dusk because the sun disappears quickly over the bulge of the earth’s equator. Skies darken overhead during nautical twilight followed by astronomical twilight during which the horizon darkens. Each period of twilight spans about 30 minutes of time. The reverse progression applies to dawn.

PERIHELION

Expect cold temperatures here on January 1st even though the earth reaches the closest point in its orbit to the sun today at 10:00pm. The northern hemisphere tilts away from the sun during the winter months which steepens the angle through which sunlight passes through the atmosphere before striking its surface. Thus, both light and heat from the sun disperse over a wider surface area than during other seasons. The southern hemisphere—bathed in summer light and heat—now tilts toward the sun.

Sunrise-Sunset
For January 2013

Day
Sunrise
Sunset
1
7:36am
5:08pm
2
7:36am
5:09pm
3
7:36am
5:10pm
4
7:36am
5:11pm
5
7:36am
5:12pm
6
7:36am
5:13pm
7
7:36am
5:14pm
8
7:36am
5:14pm
9
7:36am
5:15pm
10
7:36am
5:16pm
11
7:35am
5:17pm
12
7:35am
5:18pm
13
7:35am
5:19pm
14
7:35am
5:21pm
15
7:34am
5:22pm
16
7:34am
5:23pm
17
7:34am
5:24pm
18
7:33am
5:25pm
19
7:33am
5:26pm
20
7:32am
5:27pm
21
7:32am
5:28pm
22
7:31am
5:29pm
23
7:30am
5:30pm
24
7:30am
5:32pm
25
7:29am
5:33pm
26
7:28am
5:34pm
27
7:28am
5:35pm
28
7:27am
5:36pm
29
7:26am
5:37pm
30
7:25am
5:38pm
31
7:24am
5:40pm

MOON HAPPENINGS
Jan 4 – Last Quarter Moon rises soon after midnight.
Jan 11 – New Moon occurs at 12:44pm.
Jan 18 – First Quarter Moon sets after midnight.
Jan 26 – Full Moon occurs at 9:38pm. Watch it rise at 5:32pm.
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)

METEOR EVENTS
Watch for faint blue meteors from the Quadrantid Meteor shower between January 1-5. The radiant for this shower appears in Bootes near 0 magnitude star Arcturus which shines with a faint red-orange light. Best opportunity for viewing will be around midnight on January 3-4 before the last quarter moon rises.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. 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 fist with the thumb extended at a right angle equals 15 degrees. The hand stretched from thumb to little finger approximates 20-25 degrees. The diameter of both the full moon and the sun spans only 0.5 degree. Adjust for the size of your hand.

VISIBLE PLANETS
Jupiter – Mighty planet Jupiter—second in brightness only to Venus—relinquishes its embellishment to the morning sky this month and becomes an evening-only attribute by month’s end. Its brightness begins to wane as it moves beyond its closest approach to Earth for the current year. Look for it well above the eastern horizon as twilight fades. On January 21 the moon and Jupiter appear within one degree of one another with the Pleiades star cluster above and red-orange Aldebaran (the eye of Taurus the bull) below. (Magnitude -2.6))

Mars – The red planet sets by the time astronomical twilight ends which means it will be difficult to view from most locations within Canyonlands. If, however, you have a high vantage point soon after sunset on January 13, look for its reddish tint low on the horizon below a thin waxing crescent moon. Mars appears in the constellation Capricornus. (Magnitude +1.2)

Saturn – Golden Saturn hangs high in the eastern sky as morning twilight brightens the eastern sky. It appears in the faint constellation Libra and is flanked by blue-white Spica (Virgo) above and red-orange Antares (Scorpius) below. On January 6 find it 3.7 degrees north of a waning crescent moon. (Magnitude +0.6)

Venus – It is hard to miss Venus because of its incredible brightness, but in January it rises in the southeastern sky within one hour of the sun which minimizes its visibility. Our sister planet rises with the constellation Sagittarius—obscured by the later stages of twilight. On January 10 look for a sliver of a waning crescent moon 2.8 degrees north of Venus. (Magnitude -3.9)

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.

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.

MAJOR CONSTELLATIONS this MONTH

Overhead

Andromeda
Aries
Orion
Taurus
Triangulum

Northward
Auriga
Cassiopeia
Cepheus
Perseus
Ursa Major
Ursa Minor

Eastward
Cancer
Canis Minor
Gemini
Leo

Southward

Southward
Canis Major
Cetus

Westward

Aquarius
Cygnus
Pegasus
Pisces

The Andromeda Galaxy is visible with the unaided eye under dark skies. First find the constellation Andromeda (located between Cassiopeia and Pegasus) which forms the upper bent line of three stars that extends from the northeast corner of the Great Square of Pegasus. Locate the second star from the corner of the square, then follow the two stars perpendicular to it. The spiral galaxy—two million miles away—appears as a faint blur adjacent to the uppermost star.


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.

 
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