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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 2012
By Faylene Roth



DAYLENGTH

Longer periods of daylight are guaranteed over the next few months: a welcome 42 minutes more in January, 64 minutes more in February, a whopping 75 additional minutes in March, 68 minutes more in April, 51 more in May, and a mere ten additional minutes added in June before the shortening begins again. Sunsets have started to lengthen each day in recognition of last month’s solstice, but sunrises have not. Sunrise on the solstice occurred at 7:32am and have come later each day and will continue to do so until January 12. The reason? The earth’s orbital speed increases at perihelion which lengthens the solar day. A solar day is measured from one noon to the next with the sun being directly over the local meridian (longitude). When the earth speeds up, solar noon arrives later than twelve noon, clock time. A later solar noon results in a later sunset which causes a later sunrise the next morning. As the sun’s declination (height) increases, it overcomes the later sunsets. Eventually, the increased speed of the earth wanes (as it approaches the equinox) and delay of solar noon diminishes..

PERIHELION
Since the earth moves in an elliptical orbit, it passes through perihelion (closest point to sun) and aphelion (farthest point from sun) each year. Why? An ellipse has two foci instead of one center point. The sun sits at one of the foci. On January 4 at 6:00pm earth passes through perihelion. The difference in distance is about 3 million miles (5 million km), less than three percent of the total distance from sun to earth. Perihelion is not associated with the solstice or the tilt of the earth. It progresses through a cycle of 21,000 years during which it will pass through every season.
January 2012
DATE
SUNRISE
SUNSET
1
7:36am
5:08pm
2
7:36am
5:08pm
3
7:36am
5:09pm
4
7:36am
5:10pm
5
7:36am
5:11pm
6
7:36am
5:12pm
7
7:36am
5:13pm
8
7:36am
5:14pm
9
7:36am
5:15pm
10
7:36am
5:16pm
11
7:36am
5:17pm
12
7:35am
5:18pm
13
7:35am
5:19pm
14
7:35am
5:20pm
15
7:35am
5:21pm
16
7:34am
5:22pm
17
7:34am
5:23pm
18
7:33am
5:24pm
19
7:33am
5:25pm
20
7:32am
5:26pm
21
7:32am
5:27pm
22
7:31am
5:28pm
23
7:31am
5:30pm
24
7:30am
5:31pm
25
7:30am
5:32pm
26
7:29am
5:33pm
27
7:28am
5:34pm
28
7:27am
5:35pm
29
7:27am
5:36pm
30
7:26am
5:38pm
31
7:25am
5:39pm

CHINESE NEW YEAR
The Chinese Lunar New Year occurs on the second new moon after the Winter Solstice. This year that date is Monday, January 23, 2012.

MOON HAPPENINGS
Jan. 9 –
Full Moon occurs at 12:30am and rises at 6:04pm
Jan. 16 –
Last Quarter Moon rises shortly after midnight.
Jan. 23 –
New Moon occurs at 12:39am.
Jan. 30 –
First Quarter Moon sets soon after midnight.
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)


METEOR EVENTS
January provides good meteor activity but cold weather and moon phases often undermine its potential. Up to 40 meteors per hour can be viewed during the Quadrantids which are active January 1-5 and peak on the night of January 3/4. The radiant for the Quadrantids emanates from Bootes which rises in the northeastern sky after midnight. A waxing moon sets soon after midnight on January 1 then sets later each night after that. Viewing from 3:00am to 5:00am when the moon has set and the constellation is overhead is most promising. Other meteor radiants this month are from Cancer around midmonth (last quarter moon rises around midnight) and Coma Berenices (east of Leo) on January 18 (moon rises after 3:00am).

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.

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 -
The bright yellow orb overhead at dusk is Jupiter. It rises a bit north of due east around noon and sets soon after midnight. Jupiter appears in the constellation Pisces. The two stars above and to its left form the constellation Aries. (Magnitude -2.6)

Mars - Before midnight the small red-orange disk of Mars rises on the eastern horizon. Look below the triangular tail of Leo the Lion. Regulus is the brilliant blue star about 15 degrees to the right of Mars. On January 14 a waning gibbous moon rises southeast of Mars. (Magnitude +0)

Saturn - As Jupiter sets around midnight, the other yellow-hued planet--Saturn--rises on the eastern horizon. It appears about 45 degrees below Mars and less than 10 degrees above and to the right of Virgo’s bright, blue star, Spica. Although Mars shines more brilliantly right now, Saturn presents a larger disk. In the early morning hours of January 16 a third quarter moon forms a tight triangle with Saturn and Spica (about two degrees north of the moon). (Magnitude +0.7)

Venus - The brilliant whiteness of Venus dominates the low western sky at dusk. Venus reaches about 30 degrees above the horizon this month which increases its visibility for area viewers. It moves eastward from Capricornus into Aquarius around midmonth. (Magnitude -4.0)


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.

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

Canis Major
Cetus

Westward

Aquarius
Cygnus
Pegasus
Pisces

The Milky Way remains visible across the northern sky at dusk. To the west the galaxy’s center has retreated to the far side of the sun. To the east the outer reaches of the galaxy swing into view as the night progresses. After midnight it dangles from north to south in the western sky, disappearing over the western horizon before dawn.


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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