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Sky Happenings April 2008
Moab UT (at City Hall)
38O34’ N Latitude 109O33’ W Longitude
4048 ft - 1234 m
The Sky for April 2008
By Faylene Roth
Sunrise and Sunset Times for
April 2008

DAYLENGTH
The period of daylight lengthens by one hour eight minutes during April. Sunrise and sunset times are calculated for a flat horizon. Actual times vary by one-half hour or more depending upon the terrain. Astronomical twilight begins with a faint glow above the horizon, about one and one-half hours before sunrise. Nautical twilight, about one hour before sunrise, is marked by the appearance of shapes and color in the landscape. Civil twilight begins approximately one-half hour before sunrise when details in the landscape become clearly visible. The reverse progression applies to dusk.

MOON HAPPENINGS

April begins with a waning crescent moon in the southeastern sky at dawn. New Moon occurs on April 5. A waxing crescent reappears in the northwestern evening sky on April 7. On the evening of April 8 the moon occults (passes in front of) the Pleiades. On the night of April 11, a waxing crescent moves to within 0.5 degrees of Mars. On the evening of April 14 look directly overhead to see the gibbous moon in line with Saturn and Regulus in Leo. A nearly full moon passes below Virgo April 17-19. The Full Moon of April 20 can be seen twice. Look southwest as the moon becomes full in the early dawn skies of April 20. A nearly full moon rises again the same day in the eastern sky as twilight fades.


ALPENGLOW

As the sun sets, turn eastward to watch the pink to red glow that reflects from the LaSal peaks and the red rock rims of Grand County. As the sun moves below the horizon, its light rays miss the earth’s surface and illuminate clouds, mountain peaks, and dust particles that rise above the sun’s horizon. Short blue and green wavelengths of light are easily scattered and absorbed. Longer wavelengths of red and orange light penetrate deeper through the atmosphere and tint the peaks, rims, and clouds that face the setting sun. The red rocks of Moab intensify the effect of alpenglow.

METEOR SHOWERS

Look eastward after midnight for increased meteor activity April 16-26. The Lyrid Meteor Shower peaks April 21/22. The Lyrids generally produce 10 or more meteors per hour in the region between Hercules and Lyra, but the full moon of April 20 will diminish visibility for this year’s show.

STARGAZING

Several people with telescopes have expressed an interest in forming a local astronomy group to share interests and to offer public viewing nights during the year. Anyone interested in discussing this proposal can call me at 210-1151.

VISIBLE PLANETS

Jupiter - bright morning star, at -2.4 magnitude; rises earlier each day before dawn in the southeastern sky following Sagittarius; rises middle of the night by the end of the month.

Mars - high overhead in the early evening sky moving southeastward through Gemini; watch at the end of the month as Mars passes Pollux, the lower twin star of Gemini; both shine orange in color at an equal magnitude of +1.2.

Saturn - overhead in the constellation Leo each night; at 0 magnitude outshines 1st magnitude star Regulus, to the west in Leo.

Venus - difficult to see throughout April as it rises in the civil twilight before sunrise and sets ahead of the sun each evening.

STARGAZING
Several people with telescopes have expressed an interest in forming a local astronomy group to share interests and to offer public viewing nights during the year. Anyone interested in discussing this proposal can call me at 210-1151.

MAJOR CONSTELLATIONS OF FEBRUARY

Overhead
Cancer
Gemini
Leo

Northward
Cassiopeia
Cepheus
Ursa Major
Ursa Minor

Eastward
Bootes
Corona Borealis
Hercules
Virgo

Southward
Corvus
Crater
Hydra

Westward
Auriga
Canis Major
Canis Minor
Orion
Perseus
Taurus

Look eastward in the evening sky for kite-shaped Bootes and C-shaped Corona Borealis. Arcturus, a 0-magnitude star, sits at the southeastern point of Bootes. The open arms of Corona Borealis point north.

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 night sky from astronomical twilight to midnight. As the night and the month progress, the constellations will shift toward the northwest.

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