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NIGHT SKY HAPPENINGS

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

The Sky for August 2017
By Faylene Roth

 

Sunrise-Sunset
for August

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

DATE

SUNRISE

SUNSET

1

6:20am

8:28pm

2

6:21am

8:27pm

3

6:22am

8:26pm

4

6:23am

8:25pm

5

6:24am

8:24pm

6

6:25am

8:23pm

7

6:26am

8:22pm

8

6:26am

8:21pm

9

6:27am

8:19pm

10

6:28am

8:18pm

11

6:29am

8:17pm

12

6:30am

8:16pm

13

6:31am

8:14pm

14

6:32am

8:13pm

15

6:33am

8:12pm

16

6:34am

8:11pm

17

6:34am

8:09pm

18

6:36am

8:08pm

19

6:36am

8:06pm

20

6:37am

8:05pm

21*

6:38am

8:04pm

22

6:39am

8:02pm

23

6:40am

8:01pm

24

6:41am

8:00pm

25

6:42am

7:58pm

26

6:43am

7:57pm

27

6:43am

7:55pm

28

6:44am

7:54pm

29

6:45am

7:52pm

30

6:46am

7:51pm

31

6:47am

7:49pm

*Max Eclipse 1:37:52am
   83.32% Obscuration

The Big Dipper (Ursa Major) scoops low into the northwestern sky with the Little Dipper (Ursa Minor) tipped upside down above it. Look for the head of Draco the dragon between the Little Dipper and bright Vega (Lyra) high overhead. Follow Draco’s body eastward then trace its long tail westward then northward between the cups of the Little and Big Dippers. Hallmarks of the summer sky—the Summer Triangle and the Milky Way— are high overhead on August nights. Vega, Deneb (Cygnus), and Altair (Aquila) form the Summer Triangle. From north to south, Perseus, Cassiopeia, Cygnus, Aquila, and Sagittarius form the spine of the Milky Way. Seven of the constellations of the Zodiac spread across the southern sky from west to east if you have a broad horizon in both directions: Virgo, Libra, Scorpius, Sagittarius, Capricornus, and Aquarius.

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.

VISIBLE PLANETS
Evening (Before Midnight)
Jupiter – Look for the brightest object (exclusive of the Moon) low on the western horizon in Virgo. Jupiter's silver-white light contrasts with the bluish glimmer of nearby Spica and the warm yellow glow of Saturn. It sets before midnight on August 1 then 3-4 minutes earlier each night. By month's end Jupiter sinks below the horizon as twilight ends. (Magnitude -1.6)

Saturn – The golden glow of Saturn hovers low in the southern sky between Scorpius and Ophiucus. It transits the meridian (due south) about 10:00pm on August 1 and sets a few hours after midnight. By the end of the month Saturn appears low on the western horizon at twilight and sets within an hour of midnight.  (Magnitude +0.3)

Morning (At Twilight)
Venus – Our sister planet—the brightest of them all—pierces the eastern sky soon after 3:30am on August 1—well before morning twilight. It rises 1-2 minutes later each day. It moves across the background stars from Gemini into Cancer during the month. (Magnitude -3.8)

MOON HAPPENINGS
August 7 – Full moon (12:11pm) rises at 8:27pm.
August 15 – Dark evening skies return with the waning last quarter moon rising after midnight.
August 21 – New moon (12:30pm) yields dark skies for several nights.
August 29 – Waxing first quarter moon lights the evening sky then sets soon after midnight.

(The moon rises later each day—as little as 30 minutes to as much as one hour. Time of moonrise and moonset may also be delayed in mountainous terrain.)

Twilight is often the best time to look for Venus and Mercury because they frequently rise or set within one-half to one hour of sunrise or sunset. Twilight transitions between night and day in three stages at each end of the day. Morning twilight begins with astronomical twilight as the eastern horizon brightens —about 1-1/2 hours (nearly 2 during summer months) before sunrise when the sun is 18 ̊ below the horizon. Nautical twilight takes over for another 30-40 minutes—as the sun passes 12 ̊ below the horizon and the overhead sky turns blue and color returns to the surrounding landscape. The final stage—civil twilight—begins when the sun ascends to 6 ̊ below the horizon and provides adequate light for most outdoor activities for the half hour before the sun crests the horizon. The opposite progression occurs after sunset. Civil twilight covers the period after sunset during which daytime light quality persists for about one-half hour. Color then fades from the landscape during the 30-40 minute period of nautical twilight during which the overhead sky darkens while the western sky retains color. Astronomical twilight then transitions to night skies that are now darkened along the horizon.

MAJOR METEOR EVENTS
Shower
Peak
(August)
Range(August)
Constellation
Radiant
Rate
(hr)
Details
Conditions
(After Midnight)
Perseids
12/13
1-26
Perseus
50-80
Swift, bright,
persistent trains
Waning gibbous moon rising at 11:19pm will wash out all but the brightest

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.

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.

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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