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




The Sky for April 2009

By Faylene Roth


Sunrise and Sunset Times for
April 2008

DAYLIGHT
We gain an additional one hour and 9 minutes of sunlight this month. The period from sunrise to sunset is more than 13 hours for most of the month. Twilight adds another one and one-half hours to each end of the day. Civil twilight provides about 30 minutes of adequate light before sunrise and after sunset. Nautical twilight stretches the fading light for another 30 minutes both morning and evening. The skies reflect some light during astronomical twilight which spans another 30 minutes. Sunrise and sunset times are calculated for a flat horizon. Actual times may vary up to one-half hour or more depending upon the surrounding landscape.

MOON HAPPENINGS
April begins with a first quarter moon high in the western sky in Gemini. On April 6 a waxing gibbous moon appears below Saturn. A nearly full moon sets on the morning of April 9 around the time that the sun rises. Full moon occurs at 8:57am. A slightly waning moon rises again soon after 8:30pm. Virgo’s bright star Spica will be above it. A third quarter moon is high in the morning sky on April 17. On the morning of April 19 a waning crescent moon rises in the southeastern sky with Jupiter trailing within two degrees to the east. On April 22 an emerging crescent moon rises with Venus and Mars just before sunrise. New moon occurs on April 24 at 9:23pm.

METEOR ACTIVITY
Look for increased meteor activity April 16-25 during the Lyrid Meteor Shower. The radiant for this event lies in the constellation Lyra. Best viewing is from midnight to 4:00am when Lyra is high in the northeastern sky. It rises
just before Cygnus the Swan (aka Northern Cross). Expect 10-15 meteors per hour during peak time on the morning of April 22.

The April fireballs promise random meteor activity over the last two weeks of April. These fireballs can emanate from any region of the sky. They are extremely bright and usually exhibit long, lingering trails of light. These large meteors are the ones most likely to reach earth as meteorites. Best viewing is after midnight and before the moon rises.

OCCULTATION OF VENUS
An occultation is similar to an eclipse, but the term is used when a planet or star is eclipsed. On the morning of April 22 a faint crescent moon will rise with Venus then pass in front of it. The occultation will only be seen on the west coast. From Moab the moon and Venus will form a close conjunction with Mars a little to the east.

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

VISIBLE PLANETS
Jupiter – The bright planet high in the morning sky is Jupiter. Look for it in the southeastern sky as it rises about one hour before sunrise. It shines at magnitude -2 throughout the month.

Mars – Look for Mars in the southeastern sky this month. It rises about one hour before sunrise, following much brighter Venus into the morning twilight. If you can find the faint crescent moon on the morning of April 23, then look for Mars a little below Venus. Mars shines at magnitude +1.2 this month.

Mercury – The last half of April promises a glimpse of Mercury when it will be setting more than an hour after the sun. On the evening of April 26 it appears just below a faint crescent moon soon after sunset. Look for Mercury in the western sky after April 15. It will be shining at magnitude -1, brighter than Saturn. By month’s end, its apparent brightness fades to +0.7, about equal to Saturn.

Saturn – Look for Saturn high in the night sky below the hind flank of Leo. It shines at magnitude +0.8, a little brighter than Leo’s major star Regulus, which shines at +1.7

Venus – Watch Venus claim the mantle of morning star. It rises within minutes of sunrise for the first few days of April but quickly distances itself from the sun. It rises about one hour after Jupiter for most of the month. Venus outshines everything in the sky at magnitude -4.2, increasing slightly in brightness as the month progresses.

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,

MAJOR CONSTELLATIONS this MONTH

Overhead
Cancer
Canis Minor
Gemini
Leo

Northward
Cassiopeia
Perseus
Ursa Major
Ursa Minor


Eastward
Bootes
Corvus
Crater
Virgo

Southward
Canis Major
Hydra

Westward
Auriga
Orion
Taurus

Bright winter constellations give way to a faint spring sky of 2nd, 3rd, and 4th magnitude stars. Leo dominates the overhead sky with Regulus at its front flank and Saturn below its hind flank.

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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