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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 2016
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

8:21pm

8

6:27am

8:20pm

9

6:28am

8:19pm

10

6:28am

8:18pm

11

6:29am

8:17pm

12

6:30am

8:15pm

13

6:31am

8:14pm

14

6:32am

8:13pm

15

6:33am

8:12pm

16

6:34am

8:10pm

17

6:35am

8:09pm

18

6:36am

8:08pm

19

6:36am

8:06pm

20

6:37am

8:05pm

21

6:38am

8:03pm

22

6:39am

8:02pm

23

6:40am

8:01pm

24

6:41am

7:59pm

25

6:42am

7:58pm

26

6:43am

7:56pm

27

6:44am

7:55pm

28

6:44am

7:53pm

29

6:45am

7:52pm

30

6:46am

7:50pm

31

6:47am

7:49pm

The Milky Way splits the sky from north to south on August evenings. It’s easy to spot—stretching from Cassiopeia through Cygnus, Aquila, and Sagittarius. When you look towards Cygnus and the Summer Triangle—formed by the three stars Deneb in Cygnus, Vega in Lyra, and Altair in Aquila—you are looking across one of the dark voids within the spiral galaxy and into the Sagittarius Arm of the Milky Way. At this time of year the flattened disk we see of the Milky Way is nearly perpendicular to the Earth’s equator as well as the celestial equator. If you have a clear view of both eastern and western horizons, you can find the celestial poles of the galaxy. The north celestial pole is found in Coma Berenices low on the northwestern horizon. The south celestial pole lies within the square of Pegasus low on the eastern horizon.

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 – Jupiter lingers in the western sky for almost an hour after Venus sets. Their distance diminishes as Jupiter rises earlier and Venus rises later each day. By August 27, the two planets appear about 0.5 ̊ apart, after which Jupiter sets earlier than Venus and fades into the glare of the setting sun. (Magnitude -1.6)
Mars – Mars claims the overhead sky at the head of Scorpius. The red planet moves noticeably eastward each night—approaching Saturn later in the month when they line up vertically above red star Antares. (Magnitude -0.4)
Mercury – Look for Mercury before August 19 when it is higher in the western sky than Venus—about 15 ̊ above Venus on August 1st. The distance decreases over the next few weeks. On August 16 Mercury appears about 8 ̊ above the horizon. Within a few days it is setting ahead of Venus.
Saturn – The ringed planet trails Mars by about 15 ̊ at the beginning of August. Saturn ends its retrograde western movement on August 13 and resumes its eastern progression through the night sky. By August 24 Saturn, Mars, and Antares have converged into a nearly vertical line at the neck of Scorpius in the southwestern sky. They set in tandem around midnight until month’s end. (Magnitude +0.1)
Venus – Brilliant Venus cannot be missed on the western horizon as civil twilight gives way to nautical twilight. Venus maintains its claim as the “evening star” throughout the month as both Mercury and Jupiter do-si-do around and below it and disappear into the sun’s glare. (Magnitude -3.8)



MOON HAPPENINGS
August 2 – New moon (2:44pm) yields dark skies for several nights.
August 10 – Waxing first quarter moon lights the evening sky then sets soon after midnight.
August 18 – Full moon (3:26am) rises at 8:25pm.
(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
Waxing moon sets at 1:23am
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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