Archive for July 31, 2015

07/31/2015 – Ephemeris – Looking ahead at August in the skies

July 31, 2015 Comments off

Ephemeris for Friday, July 31st.  The Sun rises at 6:27.  It’ll be up for 14 hours and 42 minutes, setting at 9:10.   The Moon, at full today, will rise at 9:08 this evening.

Let’s look ahead at the month of August which starts tomorrow.  Daylight hours will decrease from 14 hours and 40 minutes tomorrow to 13 hours 18 minutes on the 31st.  The altitude of the sun at local noon, that is degrees of angle above the horizon will decrease from 63 degrees tomorrow to just over 53 degrees on the 31st.  Straits area listeners can subtract one more degree from those angles.  Local noon, when the sun is due south, is about 1:43 p.m.  The Perseid meteor shower will reach its peak at about 2 a.m. on the morning of the 13th, and should be spectacular with a nearly new Moon.  On the nights between now and then when the moon has set these meteor numbers will be building to the peak.  Saturn will be our only easily visible evening planet.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Star Chart

Star Chart for August 2015. Created using my LookingUp program.  Click on image to enlarge.The Moon is not plotted.

The planets and stars are plotted for the 15th at 10 p.m. EDT.  That is chart time.  Note, Traverse City is located 1 hour 45 minutes behind our time meridian.  To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.

Evening Astronomical twilight ends at 11:12 p.m. EDT on August 1st, decreasing to 10:06 p.m. EDT on the 31st.

Morning astronomical twilight starts at 4:24 a.m. EDT on August 1st, and increasing to 5:18 a.m. EDT on the 31st.

Add a half hour to the chart time every week before the 15th and subtract and hour for every week after the 15th.

For a list of constellation names to go with the abbreviations click here.

The green pointer from the Big Dipper is:

  • Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
  • Drill a hole in the bowl of the Big Dipper and the water will drip on the back of Leo the Lion.
  • Follow the arc of the Big Dipper’s handle to Arcturus
    • Continue with a spike to Spica
  • The Summer Triangle is shown in red
  • PerR in yellow is the Perseid radiant

Calendar of Planetary Events

Credit:  Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC)

To generate your own calendar go to

Times are Eastern Daylight Time on a 24 hour clock.  Some additions made to aid clarity.

Conjunctions like the Mercury-Regulus: 0.9° N means Regulus will appear 0.9° north of Mercury.

Aug 01 Sa Venus: 21.5° East of the Sun
02 Su 06:11 Moon Perigee: 362,100 km
03 Mo 22:53 Moon Descending Node
06 Th 22:03 Last Quarter
07 Fr 13:25 Mercury-Regulus: 0.9° N
08 Sa 19:22 Moon-Aldebaran: 0.7° S
10 Mo 07:11 Moon North Dec.: 18.3° N
13 Th 02:17 Perseid Shower: ZHR* = 90
14 Fr 10:54 New Moon
15 Sa 15:19 Venus Inferior Conjunction with the Sun
16 Su 10:34 Moon-Mercury: 2.2° N
17 Mo 19:05 Moon Ascending Node
17 Mo 22:33 Moon Apogee: 405,900 km
19 We 23:35 Mars-Beehive: 0.5° S
22 Sa 13:21 Moon-Saturn: 2.8° S
22 Sa 15:31 First Quarter
24 Mo 23:44 Moon South Dec.: 18.2° S
26 We 17:04 Jupiter Conjunction with the Sun
29 Sa 14:35 Full Moon
30 Su 11:24 Moon Perigee: 358,300 km
31 Mo 06:16 Moon Descending Node
31 Mo 22:12 Neptune Opposition from the Sun
Sep 01 Tu Venus: 25° West of the Sun

*ZHR – Zenithal Hourly Rate:  Approximate number of meteors per hour when the shower radiant is at the zenith.  For more information on this and other meteor showers in 2015 see the International Meteor Organization website calendar section: