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10/29/2021 – Ephemeris – Venus is at its greatest separation east from the Sun today

October 29, 2021 Comments off

This is Ephemeris for Friday, October 29th. Today the Sun will be up for 10 hours and 18 minutes, setting at 6:35, and it will rise tomorrow at 8:18. The Moon, 1 day past last quarter, will rise at 1:39 tomorrow morning.

Tonight, Venus will be at its greatest separation east of the Sun of 47 angular degrees. Having an orbit inside the Earth’s orbit, Venus never strays more than a 47-degree angle from the Sun. It has been moving away from around behind the Sun to its present position since March 26th. That’s 217 days. And now it will take only 72 days to head back to pass between the Earth and the Sun in inferior conjunction and leave the evening sky on January 9th. For this next 70 or so days, Venus will look great in telescopes. It will get larger as it approaches us and become a dazzling crescent in telescopes. Toward the latter half of December, the tiny crescent can even be made out in binoculars. It is the very best time to view Venus in a telescope.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Venus greatest elongation 7 pm 10/29/2021

Venus at greatest elongation, seen at 7 pm tonight, October 29, 2021. Note how shallow the orbit is compared with Mercury’s orbit was on Monday’s (10/25/2021) post of Mercury’s greatest western elongation as seen in the morning. Created using Stellarium.

07/31/2018 – Ephemeris – Previewing August skies

July 31, 2018 Comments off

Ephemeris for Tuesday, July 31st. The Sun rises at 6:27. It’ll be up for 14 hours and 41 minutes, setting at 9:09. The Moon, half way from full to last quarter, will rise at 11:17 this evening.

Let’s look ahead at the month of August in the skies. Daylight hours will decrease from 14 hours and 39 minutes tomorrow to 13 hours 17 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 all night on the 12th. It will be a dark night with the one day old moon setting at 10 p.m. The radiant point, where the meteors will seem to come from, will be rising higher in the northeastern sky all night. On the 17th Venus will reach ts greatest separation from the Sun in the evening sky.

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

Addendum

August Evening Star Chart

August evening star chart

Star Chart for August 2018 (10 p.m. EDT August 15, 2018). Created using my LookingUp program. Click on image to enlarge.

The planets and stars are plotted for the 15th at 10 p.m. EDT in the evening and 4:30 a.m. for the morning chart. These are the chart times. Note that Traverse City is located approximately 45 minutes behind our time meridian. (An hour 45 minutes behind our daylight saving time meridian during EDT). To duplicate the star positions on a planisphere you may have to set it to 1 hour 45 minutes earlier than the current time.

Note the chart times of 10 p.m. and 4:30 a.m. are for the 15th. For each week before the 15th add ½ hour (28 minutes if you’re picky). For each week after the 15th subtract ½ hour. The planet positions are updated each Wednesday on this blog. For planet positions on dates other than the 15th, check the Wednesday planet posts on this blog.

August Morning Star Chart

August Morning Star Chart

Star Chart for August 2018 mornings based on 4:30 a.m. August 15th. Created using my LookingUp program. Click on image to enlarge.

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

  • Pointer stars at the front of the bowl of the Big Dipper point to Polaris the North Star.
  • Leaky Big Dipper drips on Leo.
  • Follow the arc of the handle of the Big Dipper to the star Arcturus and
  • Continue with a spike to Spica.
  • The Summer Triangle is in red.
  • PerR – Perseid meteor shower radiant

Twilight

Morning Twilight Evening Twilight Dark Night Moon
Date Astronomical Nautical Nautical Astronomical Start End Illum.
2018-07-31 4h28m 5h17m 22h28m 23h17m 23h17m 23h17m 0.89
2018-08-01 4h30m 5h18m 22h27m 23h15m 23h15m 23h43m 0.82
2018-08-02 4h32m 5h20m 22h25m 23h13m 23h13m 0.74
2018-08-03 4h34m 5h21m 22h24m 23h11m 23h11m 0h09m 0.64
2018-08-04 4h36m 5h23m 22h22m 23h09m 23h09m 0h37m 0.53
2018-08-05 4h38m 5h24m 22h20m 23h07m 23h07m 1h08m 0.42
2018-08-06 4h40m 5h26m 22h18m 23h05m 23h05m 1h44m 0.31
2018-08-07 4h42m 5h27m 22h17m 23h03m 23h03m 2h26m 0.20
2018-08-08 4h43m 5h29m 22h15m 23h00m 23h00m 3h18m 0.11
2018-08-09 4h45m 5h30m 22h13m 22h58m 22h58m 4h19m 0.05
2018-08-10 4h47m 5h32m 22h11m 22h56m 22h56m 4h47m 0.01
2018-08-11 4h49m 5h33m 22h10m 22h54m 22h54m 4h49m 0.00
2018-08-12 4h51m 5h35m 22h08m 22h52m 22h52m 4h51m 0.03
2018-08-13 4h53m 5h36m 22h06m 22h49m 22h49m 4h53m 0.08
2018-08-14 4h55m 5h38m 22h04m 22h47m 23h01m 4h55m 0.16
2018-08-15 4h56m 5h39m 22h02m 22h45m 23h29m 4h56m 0.26
2018-08-16 4h58m 5h41m 22h00m 22h43m 23h59m 4h58m 0.36
2018-08-17 5h00m 5h42m 21h58m 22h41m 5h00m 0.47
2018-08-18 5h02m 5h44m 21h56m 22h38m 0h30m 5h02m 0.57
2018-08-19 5h04m 5h45m 21h54m 22h36m 1h03m 5h04m 0.67
2018-08-20 5h05m 5h47m 21h53m 22h34m 1h40m 5h05m 0.76
2018-08-21 5h07m 5h48m 21h51m 22h32m 2h22m 5h07m 0.84
2018-08-22 5h09m 5h50m 21h49m 22h29m 3h09m 5h09m 0.90
2018-08-23 5h11m 5h51m 21h47m 22h27m 4h00m 5h11m 0.90
2018-08-24 5h12m 5h53m 21h45m 22h25m 4h56m 5h12m 0.95
2018-08-25 5h14m 5h54m 21h43m 22h23m 0.99
2018-08-26 5h16m 5h55m 21h41m 22h20m 1.00
2018-08-27 5h17m 5h57m 21h39m 22h18m 0.99
2018-08-28 5h19m 5h58m 21h37m 22h16m 0.97
2018-08-29 5h21m 6h00m 21h35m 22h14m 0.92
2018-08-30 5h22m 6h01m 21h33m 22h11m 22h11m 22h40m 0.86
2018-08-31 5h24m 6h02m 21h31m 22h09m 22h09m 23h09m 0.78

Twilight calendar was generated in Cartes du Ciel.

NASA Calendar of Planetary Events

Date        Time    Event
Aug 01  We          Venus: 45.1° E
    04  Sa  2:18 pm Last Quarter
    06  Mo  2:35 pm Moon-Aldebaran: 1.1° S
    08  We  6:33 pm Moon North Dec.: 20.8° N
    08  We  9:59 pm Mercury Inferior Conj.
    10  Fr  9:40 am Moon Ascending Node
    10  Fr  2:05 pm Moon Perigee: 358100 km
    11  Sa  5:47 am Partial Solar Eclipse (NE Canada to Asia)
    11  Sa  5:58 am New Moon
    12  Su  8:44 pm Perseid Meteor Shower: ZHR = 90
    14  Tu  9:35 am Moon-Venus: 6.4° S
    17  Fr  6:38 am Moon-Jupiter: 4.8° S
    17  Fr 11:59 am Venus Greatest Elongation: 45.9° E
    18  Sa  3:49 am First Quarter
    20  Mo 10:07 pm Mercury-Beehive: 5.9° S
    21  Tu  5:55 am Moon-Saturn: 2.4° S
    21  Tu 10:58 pm Moon South Dec.: 20.8° S
    23  Th  7:23 am Moon Apogee: 405700 km
    24  Fr 12:51 am Moon Descending Node
    26  Su  7:56 am Full Moon
    26  Su  3:59 pm Mercury Greatest Elongation: 18.3° W
Sep 01  Sa          Venus: 45° E

Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA’s GSFC),
http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html

If you go to the above site you can print out a list like the above for the entire year
or calendar pages for your time zone.

Sun and Moon Rising and Setting Events

     LU              Ephemeris of Sky Events for Interlochen/TC
     August, 2018    Local time zone: EDT
     +-----------------------------------------------------------------------+
     | DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
     |      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
     +=======================================================================+
     |Wed  1| 06:29a  09:08p  14:39 | 10:23p  05:13a |      Rise 11:43p   77%|
     |Thu  2| 06:30a  09:07p  14:37 | 10:22p  05:14a |      Rise 12:09a   68%|
     |Fri  3| 06:31a  09:05p  14:34 | 10:20p  05:16a |      Rise 12:37a   58%|
     |Sat  4| 06:32a  09:04p  14:32 | 10:18p  05:17a |L Qtr Rise 01:08a   47%|
     +------+-----------------------+----------------+-----------------------+
     |Sun  5| 06:33a  09:03p  14:29 | 10:17p  05:19a |      Rise 01:44a   37%|
     |Mon  6| 06:34a  09:01p  14:27 | 10:15p  05:20a |      Rise 02:27a   26%|
     |Tue  7| 06:35a  09:00p  14:24 | 10:13p  05:22a |      Rise 03:18a   17%|
     |Wed  8| 06:37a  08:59p  14:22 | 10:11p  05:23a |      Rise 04:20a    9%|
     |Thu  9| 06:38a  08:57p  14:19 | 10:10p  05:25a |      Rise 05:30a    3%|
     |Fri 10| 06:39a  08:56p  14:16 | 10:08p  05:26a |      Rise 06:45a    0%|
     |Sat 11| 06:40a  08:54p  14:14 | 10:06p  05:28a |New   Set  09:21p    1%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 12| 06:41a  08:53p  14:11 | 10:04p  05:29a |      Set  09:58p    4%|
     |Mon 13| 06:42a  08:51p  14:08 | 10:02p  05:31a |      Set  10:30p   10%|
     |Tue 14| 06:44a  08:50p  14:06 | 10:00p  05:32a |      Set  11:00p   17%|
     |Wed 15| 06:45a  08:48p  14:03 | 09:59p  05:34a |      Set  11:29p   27%|
     |Thu 16| 06:46a  08:46p  14:00 | 09:57p  05:35a |      Set  11:59p   36%|
     |Fri 17| 06:47a  08:45p  13:57 | 09:55p  05:37a |      Set  12:29a   47%|
     |Sat 18| 06:48a  08:43p  13:54 | 09:53p  05:38a |F Qtr Set  01:03a   57%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 19| 06:49a  08:42p  13:52 | 09:51p  05:40a |      Set  01:40a   66%|
     |Mon 20| 06:51a  08:40p  13:49 | 09:49p  05:41a |      Set  02:22a   75%|
     |Tue 21| 06:52a  08:38p  13:46 | 09:47p  05:43a |      Set  03:09a   83%|
     |Wed 22| 06:53a  08:37p  13:43 | 09:45p  05:44a |      Set  04:00a   89%|
     |Thu 23| 06:54a  08:35p  13:40 | 09:43p  05:46a |      Set  04:56a   94%|
     |Fri 24| 06:55a  08:33p  13:37 | 09:41p  05:47a |      Set  05:54a   98%|
     |Sat 25| 06:56a  08:31p  13:34 | 09:39p  05:48a |      Set  06:54a  100%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 26| 06:58a  08:30p  13:31 | 09:37p  05:50a |Full  Rise 08:54p  100%|
     |Mon 27| 06:59a  08:28p  13:29 | 09:35p  05:51a |      Rise 09:21p   98%|
     |Tue 28| 07:00a  08:26p  13:26 | 09:33p  05:53a |      Rise 09:47p   94%|
     |Wed 29| 07:01a  08:24p  13:23 | 09:31p  05:54a |      Rise 10:13p   88%|
     |Thu 30| 07:02a  08:23p  13:20 | 09:29p  05:56a |      Rise 10:40p   81%|
     |Fri 31| 07:04a  08:21p  13:17 | 09:27p  05:57a |      Rise 11:09p   72%|
     +-----------------------------------------------------------------------+
     * Nautical Twilight
     ** Moon rise or moon set, whichever occurs between sunrise and sunset

Ephemeris of Sky Events is created with my DOS version LookingUp program.

06/04/2015 – Ephemeris – Venus’ greatest eastern elongation from the Sun is Saturday

June 4, 2015 Comments off

Ephemeris for Thursday, June 4th. Today the Sun will be up for 15 hours and 24 minutes, setting at 9:23. The Moon, 2 days past full, will rise at 11:06 this evening and tomorrow the Sun will rise at 5:58.

On Saturday Venus will reach its greatest eastern elongation or separation from the Sun of 45.4 degrees angle. It’s phase should be that of exactly half illuminated by the sun. The problem is that the date it is exactly half illuminated can vary from 1 to 4 days from the greatest elongation. Of course this is something that has to be seen in a telescope. Try to catch Venus in bright twilight so its bright glare is minimized. I find that a moon filter fitted to the eyepiece gets rid of the glare nicely. After that time Venus will to begin to move toward the Earth, then curve around in its orbit to pass between the Earth and the Sun. As it does so it will increase its apparent size and its phase will become a crescent.

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

Addendum

Venus at greatest eastern elongation

Venus at elongation with a plot of its orbit as seen from Earth at 10:30 p.m. June 6, 2015. Note that the orbit appears at a line. It is this time of year that the Earth passes through the plane of Venus’ orbit. Back in 2012 this occurred when Venus was at inferior conjunction on June 5th. It passed in front of the Sun in the rare transit of Venus. Created using Stellarium.

Greatest elongation diagram

Diagram showing the geometry of a greatest elongation. Note that the sight line is perpendicular to the Venus-Sun line. So the phase should be exactly at dichotomy (half illuminated). Additional lines added to an uncredited diagram.

06/01/2015 – Ephemeris – Starting orbit 41 looking at June skies

June 1, 2015 Comments off

Ephemeris for Monday, June 1st.  Today the Sun will be up for 15 hours and 20 minutes, setting at 9:21.   The Moon, 1 day before full, will set at 6:17 tomorrow morning and tomorrow the Sun will rise at 6:00.

We’ll start Ephemeris’ 41st orbit of the Sun by looking at the skies of June.  There’ will be a lot of sun in June and very little night.  The daylight hours will increase a bit from 15 hours and 20 minutes today to 15 hours and 34 minutes on the 21st, retreating back to 15 hours 31 minutes at month’s end.  At this time of the year the sunset times for Ludington, Interlochen, Petoskey and Mackinaw City are very nearly the same.  However the sunrise times are at their most divergent.  With Ludington’s sunrise being 14 minutes later than Mackinaw City’s.  The altitude of the sun above the southern horizon at local noon will hover around 68 to 69 degrees.  Local noon, when the sun is actually due south will occur at about 1:43 p.m.  Here’s what we’ve been waiting for:  Summer will start on the 21st at 12:38 p.m.

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

Addendum

June Star Chart

Star Chart for June 2015. Created using my LookingUp program.

The Moon is not plotted.

The planets and stars are plotted for the 15th at 11 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 set it to 1 hour 45 minutes earlier than the current time.

Evening Astronomical twilight ends at 11:43 p.m. EDT on June 1st, increasing to midnight EDT on the 30th.

Morning astronomical twilight starts at 4:38 a.m. EDT on June 1st, and decreasing to 3:31 a.m. EDT on the 30th.

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

Calendar of Planetary Events

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

To generate your own calendar go to http://eclipse.gsfc.nasa.gov/SKYCAL/SKYCAL.html

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

Conjunctions like the Moon-Saturn: 2.1° S means Saturn will appear 2.3° south of the Moon.

Jun 01 Mo Venus: 45.3° E
01 Mo 16:02 Moon-Saturn: 2° S
02 Tu 12:19 Full Moon
03 We 17:10 Moon South Dec.: 18.4° S
06 Sa 14:59 Venus Elongation: 45.4° E
09 Tu 11:42 Last Quarter
10 We 00:39 Moon Perigee: 369700 km
10 We 19:29 Moon Descending Node
13 Sa 04:59 Venus-Beehive: 0.6° N
14 Su 10:39 Mars Solar Conjunction
16 Tu 10:05 New Moon
16 Tu 15:47 Moon North Dec.: 18.5° N
20 Sa 07:28 Moon-Venus: 6.3° N
  21 Su 12:38 Summer Solstice
23 Tu 05:39 Mercury-Aldebaran: 1.9° N
23 Tu 13:01 Moon Apogee: 404100 km
24 We 07:03 First Quarter
24 We 12:59 Mercury Elongation: 22.5° W
24 We 13:23 Moon Ascending Node
28 Su 21:27 Moon-Saturn: 2.1° S
30 Tu 22:14 Venus-Jupiter: 0.3° N
Jul 01 We 02:48 Moon South Dec.: 18.4° S
01 We Venus: 42.4° E