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Sky Happenings May 2007
Moab UT (at City Hall)
38O34’ N Latitude 109O33’ W Longitude
4048 ft - 1234 m

The Sky for May 2007

By Faylene Roth


Meteor Showers
A weak display at best, The Eta Aquarids Meteor Shower is compromised this year by the waning full moon of May 2. The meteors radiate from the constellation Aquarius which rises in the northeastern sky, to the south of Cassiopeia, after midnight. Peak viewing time is May 6-12.

Blue Moon
Blue moons are rare no matter how you define them. The phrase has been used for hundred of years to refer to rare, absurd, or unlikely occurrences. It is true that the moon can look blue, if the sky is fulled with volcanic dust or smoke particles from huge forest fires. As you may have guessed, it does not happen often. The Maine Farmers Almanac laid the groundwork for the current definition of blue moon back in the 1930’s and 1940’s. A typical year has 12 full moons, three full moons for each of the four seasons. Occasionally, there would be 13 full moons in a year because the moon’s orbit of 29-1/2 days is shorter than most calendar months (February excepted). Each month’s full moon had a name and was sometimes used to determine religious observances. The Almanac cast the fourth full moon of that particular season as the oddball, and one of its astronomers called it the Blue Moon. That left the moon name nearest the solstice or equinox intact. The formula for calculating these Blue Moons was later discovered but misinterepreted by a reporter for Sky and Telescope Magazine and then later picked up by the radio program Star Date. As a result, we now consider a blue moon to be the second full moon within a calendar month. By either definition, a blue moon is rare. They usually occur every two to three years, although some years have had two blue moons by the current definition. Blue Moons can occur in both January and March of the same year, leaving February without a full moon of its own.


A full moon rises on Wednesday, May 2, at 8:57 pm and again on Thursday, May 31, at 8:53 pm. In Canyon Country these times may be delayed by one-half hour or more, depending upon your viewing site. The moon sets about one hour later each night during the first week of May. By then it is rising after midnight and setting before sunset until May 16. the new moon occurs on May 16, after which it reappears in the western sky at sunset. On May 17 look toward the western horizon for the elusive planet Mercury near a slender crescent moon soon after sunset. On May 19 the planet Venus will be close to the waxing crescent. The waxing moon appears higher in the sky each night. By the second full moon on May 31, it will rise about 20 minutes after sunset.


Jupiter - rises before midnight at the beginning of the month and around 9:00 pm by the end of the month
Mars - rises in the early morning hours and sets well before sunset
- visible during the last half of May soon after twilight in the western sky; on May 17 look for it near the crescent moon;
Saturn - high in the western sky each evening, just west of the mane of Leo the Lion
Venus - rises higher in the western sky each evening, moving towards Gemini; on May 19 it passes very near the crescent moon.

Sunrise/Sunset chart
Sunrise is calculated as though the horizon is at the same elevation as Moab. Dawn, or twilight, occurs in three stages. Civil twilight occurs approximately one-half hour before official sunrise; you can easily function without artificial light. Nautical twilight, about one hour before sunrise, may require artificial light to assist your movements. Astronomical twilight occurs about one and one-half hours before sunrise. A faint glow will appear above the horizon. The same progression applies to dusk. The surrounding cliffs can prolongtwilight by up to one-half hour or more.

Major Constellations of April

Ursa Major
Ursa Minor
Cygnus (Northern Cross)
Corona Borealis

By the end of May, Vesta, one of only two asteriods visible with the unaided eye, will appear as a bright star just south of the constellation Ophiuchus. It will be as bright as the star Antares just below Ophiuchus in the constellation Scorpius.

Hold the star chart high above your head and
match the compass directions to the
direction you are facing.
Sky Chart - Moab
As the night and the
month progress, the
constellations will shift toward
the west. Gemini will move beyond
the western horizon by the end of the month.

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