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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 2015
By Faylene Roth

 

Sunrise-Sunset
for May

(The time of sunrise and sunset assumes a flat horizon. Actual time may vary depending upon the landscape.)

DATE

SUNRISE

SUNSET

1

6:21am

8:10pm

2

6:20am

8:11pm

3

6:19am

8:12pm

4

6:18am

8:13pm

5

6:17am

8:14pm

6

6:16am

8:15pm

7

6:14am

8:16pm

8

6:13am

8:17pm

9

6:12am

8:17pm

10

6:11am

8:18pm

11

6:10am

8:19pm

12

6:09am

8:20pm

13

6:08am

8:21pm

14

6:08am

8:22pm

15

6:07am

8:23pm

16

6:06am

8:24pm

17

6:05am

8:25pm

18

6:04am

8:26pm

19

6:03am

8:26pm

20

6:03am

8:27pm

21

6:02am

8:28pm

22

6:01am

8:29pm

23

6:01am

8:30pm

24

6:00am

8:31pm

25

5:59am

8:31pm

26

5:59am

8:32pm

27

5:58am

8:33pm

28

5:58am

8:34pm

29

5:57am

8:34pm

30

5:57am

8:35pm

31

5:56am

8:36pm

The Milky Way is absent from the night sky until well beyond midnight for most of the month. The dominant stars in the overhead sky—Arcturus (Boötes), Spica (Virgo), and Regulus (Leo)—form an acute isosceles triangle with Jupiter (Cancer) outshining them on their western flank and evermore brilliant Venus near the western horizon. On the eastern horizon, Vega (Lyra) rises in the northeastern sky and Saturn (Libra) in the southeastern sky.

Twilight extends the period of daylight in three stages at each end of the day. Morning twilight begins with astronomical twilight—about 1-1/2 hours (nearly 2 during summer months) before sunrise—as the eastern horizon brightens. Nautical twilight continues—as the overhead sky turns blue and color returns to the surrounding landscape—for another 30-40 minutes. The final stage—civil twilight—provides adequate light for most outdoor activities for the half hour before the sun crests the horizon. The opposite progression occurs after sunset.

DAYLENGTH
As the northern hemisphere approaches its direct face-off with the sun on June 21, sunlight strikes the Earth more directly at higher latitudes. The light filters farther around the horizons which lengthens the period of daylight as well as the length of the twilight period. The period of daylight continues to increase this month—another 53 minutes—but at a slower rate. Longer periods of twilight will be noticeable by month’s end.

MOON HAPPENINGS
May 3 – Full moon (9:42pm) rises at 7:58pm.
May 11 – Dark evening skies until after midnight when the waning last quarter moon rises.
May 17 –Dark sky period for several days before and after the new moon (10:13pm).
May 25 – Waxing first quarter moon brightens evening skies until after midnight.

NORTH GALACTIC POLE
Follow the arc of the handle of the Big Dipper on a moonless night southward to Arcturus (Boötes). Look upward for the constellation Coma Berenices which is defined by three faint stars that form two lines perpendicular to one another. Gaze into this space and you are looking out through the top of our Milky Way Galaxy. Few stars are visible in this region because it is a mere 3,000 light years to the top edge of the galaxy. Beyond, though, imagine the thousands of other galaxies seen only with the world’s largest telescopes.
.
VISIBLE PLANETS
Jupiter – Find Jupiter high in the western sky near the center of the faint constellation Cancer. It sets within a few hours after midnight. Find the faint Beehive Cluster (M44) about 2-3 ̊ across the center of Cancer and the head of the constellation Hydra about 10 ̊ southwest of Jupiter. (Magnitude -2.0)
Mercury – Look for Mercury in the early evening sky during the first half of the month. It reaches its greatest eastward elongation on May 7. That puts it high enough on the western horizon to see during nautical twilight. Find it about 25 ̊ below Venus. (Magnitude 0)
Saturn – Saturn rises each evening during nautical twilight and is visible throughout the night. It appears at the head of Scorpius but passes into the constellation of Libra at midmonth. On May 23 Saturn reaches opposition (far side of Earth from the sun), which is its closest position to Earth for the year. It will be fully illuminated like a full moon. Saturn’s rings are currently tilted at a good angle for viewing, so take the opportunity to view it through a telescope if possible. (Magnitude +0.9)
Venus – Venus lingers above the western horizon until nearly midnight. Look for it about 35 ̊ below Jupiter on the line of the ecliptic in the constellation Gemini. Venus brightens as it moves closer to Earth, even though its face is not fully illuminated. The inner planets pass through phases like the moon, but on a yearly cycle. Currently, Venus looks similar to a quarter moon when viewed through a telescope. (Magnitude -4.2)

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; 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.

MAJOR CONSTELLATIONS this MONTH


Overhead
Ursa Minor
Ursa Major
Boötes
Corona Borealis
Leo
Virgo
Corvus
Crater
Hydra (tail)

Eastward
Cygnus
Lyra
Hercules
Ophiucus
Libra

Westward
Auriga
Gemini
Cancer
Canis Minor
Hydra (head)


MAJOR METEOR EVENTS
Shower
Peak
(May)
Range
(May)
Constellation Radiant
Rate
(/hr)
Details
Conditions
(After Midnight)
Eta Aquarids
5/6
1-28
Aquarius
10-30
After midnight-fireballs possible
Moonlit skies through May 15
Fireballs
9-11
9-11
Aquarius
?
In southeastern skies
Visible in bright moonlight
Best time to view any meteor event is between midnight and morning twilight when the radiant is overhead. Trace the path of any meteor backwards through the sky to reach its radiant--the region of the sky from which meteors appear to originate.

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

Note: Hold your hand at arm’s length to measure apparent distances in the sky. The width of the little finger approximates 1.5̊. Middle, ring, and little finger touching represent about 5̊. The width of a fist is about 10̊. The fist with the thumb extended at a right angle equals 15̊. The hand stretched from thumb to little finger approximates 20̊-25̊. The diameter of both the full moon and the sun spans only 0.5̊. Adjust for the size of your hand.

 
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