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SKY HAPPENINGS

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

The Sky for March 2012
By Faylene Roth



DAYLENGTH

March 19 marks the Vernal Equinox when the sun is above the horizon for 12 hours. Three days earlier, though, light overtakes the darkness of winter. The 12-hour day on March 16 is due to refraction (light rays curve as they pass through the earth’s atmosphere) which makes the sun visible while it is still below the horizon. We gain 75 additional minutes of sunlight this month. Daylight saving time (beginning March 11—advance clocks forward one hour) transfers one hour of morning light to the afternoon. By month’s end, earlier sunrises have restored one-half hour of the lost morning light.

EQUINOX
Spring comes early this year to canyonlands. Many calendars mark March 20 as the first day of spring because astronomers use Universal Time (UT), which is six hours ahead of MDT, seven hours ahead of MST. So, in Utah, the vernal equinox occurs March 19 at 11:14pm MDT. Equinoxes mark the point when and where the sun’s position on the ecliptic intersects the celestial equator. The March star map shows a point of intersection in Virgo, but it displays the night sky and reveals the sun’s position at the autumnal equinox. The point of intersection at the spring equinox occurs in Pisces, a position which can be viewed in the night sky in September.

ZODIACAL LIGHT
At the equinoxes the sun rises due east and sets due west, which means that at sunrise and sunset the rays of the sun shoot straight up into the sky in a line perpendicular to the horizon. For sky gazers this produces an unusual light show—the zodiacal light—for several weeks before and after the equinoxes. The light show appears about two hours before sunrise (before twilight brightens the morning sky), or about two hours after sunset (once twilight has faded from the horizon). Before the spring equinox, face the western horizon near where the sun set. Look for a faint, stationary, cone-shaped beam of light piercing the dark sky in a nearly perpendicular line (slightly angled to the left) passing near Venus and Jupiter. After the equinox face east, towards the point where the sun will rise, and look for a beam angled slightly to the right. The zodiacal light extends as much as 50-60 degrees above the horizon and illuminates a cloud of dust in the inner solar system well beyond our atmosphere.

DATE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
SUNRISE
6:50am
6:48am
6:47am
6:45am
6:44am
6:42am
6:41am
6:39am
6:38am
6:36am
7:35am
7:33am
7:32am
7:30am
7:29am
7:27am
7:25am
7:24am
7:22am
7:21am
7:19am
7:18am
7:16am
7:15am
7:13am
7:11am
7:10am
7:08am
7:07am
7:05am
7:04am
SUNSET
6:12pm
6:13pm
6:14pm
6:15pm
6:16pm
6:17pm
6:18pm
6:19pm
6:20pm
6:21pm
7:22pm
7:23pm
7:24pm
7:25pm
7:26pm
7:27pm
7:28pm
7:29pm
7:30pm
7:31pm
7:32pm
7:33pm
7:34pm
7:35pm
7:36pm
7:36pm
7:37pm
7:38pm
7:39pm
7:40pm
7:41pm



MOON HAPPENINGS
March 8
– Full Moon occurs at 3:39am and rises at 7:08pm.
March 14 – Last Quarter Moon rises several hours after midnight.
March 22 – New Moon occurs at 8:37am.
March 30 – First Quarter Moon sets several hours after midnight.
(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)


COMET EVENTS
No major meteor events occur this month, but another astronomical event is on view in the circumpolar skies of the northern hemisphere. Comet Garrard promises to be a naked-eye event as it approaches its nearest point to the sun on March 5. Look for a greenish blur at the limit of visibility (magnitude +6) near the end stars of Ursa Minor’s dipper. The comet, visible throughout the night, moves NNW until March 11, then turns SW and moves back through the Little Dipper during the rest of March. Use binoculars to view the tail.

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 -
Look high in the western sky for Jupiter’s brilliant yellow disk which sets around 10:00pm (in Aries). On the night of March 14/15 it approaches to within three degrees of Venus. (Magnitude -2.1)

Mars -
On March 1 Mars rises within one minute of sunset. On March 3 it is at opposition (opposite side of Earth from the sun), which presents its face like a full moon. On March 5 its orbit brings it to its closest point to Earth for the next two years. Its deep red orb is easily recognized below Leo, and it remains visible throughout most of the night.. (Magnitude -1.2)

Mercury -
Look for Mercury about 30 degrees below Venus (in Pisces) during the first week of March. On March 5 it reaches its greatest elongation, reaching about 18 degrees above the horizon at sunset. Mercury is headed for inferior conjunction (pass between Earth and sun) and will disapear into the sun’s glare by midmonth. (Magnitude +1.2)

Saturn -
Watch Saturn rise in the eastern sky about 10:00pm. It will be in the western sky by dawn. Saturn’s bright yellow orb appears to the left of Virgo’s bright star Spica. (Magnitude +0.4)
Venus - Follow Venus from Pisces into Aries this month. It moves into conjunction (close proximity) with Jupiter on the night of March 14/15. (Magnitude -4.3)

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

Cancer
Canis Minor
Gemini

Northward

Cassiopeia
Cepheus
Perseus
Ursa Major
Ursa Minor

Eastward

Bootes
Corona Borealis
Leo
Virgo

Southward

Canis Major
Corvus
Hydra

Westward

Aries
Auriga
Orion
Taurus

From east to west, Mars, Moon, Sirius, Jupiter, Venus, Mercury—the six brightest objects visible from the northern hemisphere—can be seen March 1-5. All shine at negative magnitudes. Mercury quickly slips below the western horizon.


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.

Sky Chart for March 2012

 
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