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SKY HAPPENINGS

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

The Sky for May 2012
By Faylene Roth



DAYLENGTH

May provides 51 minutes of additional daylight for daytime activities. Later in the month the lingering twilight of summer becomes noticeable. As the earth moves towards the far end of its elliptical orbit, it’s northern hemisphere tilts towards the face of the sun. The light rays of the rising and setting sun bend around the horizon due to refraction. With a smaller circumference presented to the sun, the light reaches farther beyond the horizon. The result is that the length of twilight is extended from one and one-half hours to nearly two hours each morning and evening. Twilight occurs in three stages. After sunset, civil twilight provides adequate light for most detailed work for about 30 minutes. Nautical twilight marks the next 30-40 minute period when color and detail disappear in the surrounding landscape and overhead skies darken. The final period of twilight—astronomical twilight—continues an additional 30-40 minutes during which light fades from the horizon. The reverse progression takes place before sunrise.

METEOR EVENTS
The Eta Aquarids—May 1-12—compete with a full moon this year. The radiant for this meteor shower emanates from Aquarius which begins to rise after midnight. Best viewing is May 4-7 after 4:00am when the meteors are active in the southeastern sky and the moon is low in the western sky. Expect about 10 meteors per hour. Other meteor activity may be visible in the early morning sky east of Bootes and in the southern sky between Scorpius and Libra.

ANNULAR SOLAR ECLIPSE
Solar eclipses occur during a new moon when the earth, moon, and sun pass one another on the same plane. This allows the moon to cross the face of the sun as seen from earth. An annular solar eclipse happens when the distance between sun and moon is too great for the moon to block the entire disk of the sun. Viewers in the center of the eclipse path (which includes southwestern Utah) see a thin ring of light encircling the darkened center of the sun. Viewers from Moab will see a partial annular eclipse. From here the sun will look like a huge crescent moon. The eclipse begins at 6:22pm and ends at sunset (8:28pm). Maximum eclipse occurs at 7:32pm.

Salt Lake City’s Clark Planetarium provides maps of the eclipse path through Utah and safe viewing methods (including construction of a pinhole projector) on their website at: http://clarkplanetarium.org. They warn that viewing an annular solar eclipse without proper eye protection can permanently damage your vision. Only—AND I STRESS ONLY—Grade 14 welder goggles designed specifically for arc welding or specially-designed eclipse shades are safe. Viewing aids to AVOID are: polarized sunglasses, doubled-up sunglasses, smoked glass, and exposed camera film. See their website for further details.

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
6:20am
6:19am
6:18am
6:17am
6:16am
6:15am
6:14am
6:13am
6:12am
6:11am
6:10am
6:09am
6:08am
6:07am
6:06am
6:05am
6:04am
6:04am
6:03am
6:02am
6:01am
6:01am
6:00am
5:59am
5:59am
5:58am
5:58am
5:57am
5:57am
5:56am
5:56am
SUNSET
8:11pm
8:12pm
8:13pm
8:13pm
8:14pm
8:15pm
8:16pm
8:17pm
8:18pm
8:19pm
8:20pm
8:21pm
8:22pm
8:23pm
8:24pm
8:24pm
8:25pm
8:26pm
8:27pm
8:28pm
8:29pm
8:30pm
8:30pm
8:31pm
8:32pm
8:33pm
8:34pm
8:34pm
8:35pm
8:36pm
8:36pm


MOON HAPPENINGS
May 5
- Full Moon occurs at 9:35pm and rises at 8:11pm.
May 12 - Last Quarter Moon rises several hours after midnight.
May 20 - New Moon occurs at 5:47pm.
May 28 - First Quarter Moon sets soon after midnight.

(The time of moonrise and moonset assumes a flat horizon. Actual time may vary.)

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
Mars -
Find Mars in the western sky in Leo. Differentiate it from 1st magnitude Regulus (Leo) by its reddish tint. (Magnitude +1.0)

Saturn - Look for Saturn high in the southeastern sky in Virgo. It shines with a yellow light compared to bluish-white Spica (Virgo). (Magnitude +0.3)

Venus - Watch Venus’s descent towards the western horizon each evening. It disappears from view by month’s end as it begins its pass between Earth and sun. With binoculars, it appears as a thin crescent. (Magnitude -4.5)


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

Bootes
Leo

Northward

Cassiopeia
Cepheus
Draco
Ursa Major
Ursa Minor

Eastward

Corona Borealis
Hercules
Lyra

Southward

Corvus
Hydra
Virgo

Westward

Auriga
Canis Minor
Gemini

Identify these planets and bright stars: locate the Big Dipper (Ursa Major) overhead. Trace an arc SE through its handle to Arcturus (Bootes). Continue the arc to Saturn situated above Spica (both in Virgo). Trace a wide arc NW from Spica to Mars then Regulus (both in Leo) and west to the little dog star, Procyon (below Pollux and Castor, the Gemini twins). Swing upward to Venus and curve back to Capella (Auriga). By month’s end, Venus and Capella drop below the western horizon and Vega (Lyra) and Deneb (Cygnus) rise in the east.


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.

May 2012 Sky Chart


 
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