Bob Moler's Ephemeris Blog

Ephemeris for Wednesday, September 26th. The Sun will rise at 7:34. It’ll be up for 11 hours and 57 minutes, setting at 7:32. The Moon, 2 days past full, will rise at 8:43 this evening.

Let’s look at the bright planets today. Four of them are visible in the evening sky. The brilliant Venus will be visible in the western twilight briefly from about 7:50 p.m. until it sets at 8:14 p.m. Jupiter will be in the southwest as it gets dark. It is only outshone by Venus, and the Moon. The big planet will set at 9:24 p.m. Saturn will start the evening low in the southern sky and will stay relatively low, above the Teapot of Sagittarius. It will be due south at sunset and will set at 11:54 p.m. Mars will be low in the south-southeast as the skies darken tonight. and is now 53.5 million miles (86.2 million km) away. Mars will be due south at 9:48 p.m., and it will set at 2:14 a.m. It’s diameter is 16.4 seconds of arc, quite small in telescopes.

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

Addendum

Here are the apparent diameters of the above planets:
    Venus 43.7″ (seconds of arc)
    Jupiter 32.8″
    Saturn 16,6″, rings 38.6″
    Mars 16,4″

Jupiter’s moon Ganymede will begin to transit the planet at 8:50 p.m. EDT (00:50 UT September 27).

Ephemeris for Friday, August 31st. The Sun will rise at 7:04. It’ll be up for 13 hours and 17 minutes, setting at 8:21. The Moon, 2 days before last quarter, will rise at 11:09 this evening.

Let’s look at the skies for the month of September. The Sun will moving at its greatest speed in its retreat to the south. Daylight hours in the Interlochen/Traverse City area and will drop from 13 hours and 14 minutes tomorrow to 11 hours 45 minutes on the 30th. The altitude of the Sun above the southern horizon at local noon will be 54 degrees tomorrow, and will descend to 42 degrees on the 30th. The season of summer is getting short, so enjoy it while you can. Summer ends and autumn begins at 9:54 p.m. on September 22nd. Venus is retreating toward the Sun now, though still moving eastward against the stars. Jupiter, Saturn and Mars are all moving eastward with respect to the stars, but are moving westward in the sky by our clocks.

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

Addendum

September Evening Star Chart

Star Chart for September 2018 (10 p.m. EDT September 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 6 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.

September Morning Star Chart

Star Chart for September 2018 mornings based on 6 a.m. September 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.
• Follow the arc of the handle of the Big Dipper to the star Arcturus
• The Summer Triangle is in red.

Twilight

Twilight calendar was generated using Cartes du Ciel (Sky Charts).

NASA Calendar of Planetary Events

Date        Time    Event
Sep 01  Sa          Venus: 45° E
    01  Sa 12:45 am Venus-Spica: 1.2° S
    02  Su  9:34 pm Moon-Aldebaran: 1.2° S
    02  Su 10:37 pm Last Quarter
    05  We  2:56 am Moon North Dec.: 20.8° N
    06  Th  6:42 am Moon Ascending Node
    06  Th 10:13 pm Moon-Beehive: 1.4° N
    07  Fr  1:19 pm Neptune Opposition
    07  Fr  9:21 pm Moon Perigee: 361400 km
    09  Su  2:01 pm New Moon
    13  Th 10:21 pm Moon-Jupiter: 4.6° S
    16  Su  7:15 pm First Quarter
    17  Mo 12:46 pm Moon-Saturn: 2.3° S
    18  Tu  5:35 am Moon South Dec.: 20.9° S
    19  We  8:54 pm Moon Apogee: 404900 km
    20  Th  5:30 am Moon Descending Node
    20  Th  9:47 pm Mercury Superior Conj.
    22  Sa  9:54 pm Autumnal Equinox
    24  Mo 10:53 pm Full Moon (Harvest Moon)
    30  Su  3:06 am Moon-Aldebaran: 1.4° S
Oct 01  Mo          Venus: 32.9°

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
     September, 2018    Local time zone: EDT
     +-----------------------------------------------------------------------+
     | DATE |  SUN     SUN  DAYLIGHT|   TWILIGHT*    |MOON  RISE OR    ILLUM |
     |      |  RISE    SET    HOURS |  END    START  |PHASE SET** TIME FRACTN|
     +=======================================================================+
     |Sat  1| 07:05a  08:19p  13:14 | 09:25p  05:58a |      Rise 11:43p   62%|
     +------+-----------------------+----------------+-----------------------+
     |Sun  2| 07:06a  08:17p  13:11 | 09:23p  06:00a |L Qtr Rise 12:22a   51%|
     |Mon  3| 07:07a  08:15p  13:08 | 09:21p  06:01a |      Rise 01:08a   40%|
     |Tue  4| 07:08a  08:13p  13:05 | 09:19p  06:02a |      Rise 02:03a   29%|
     |Wed  5| 07:09a  08:12p  13:02 | 09:17p  06:04a |      Rise 03:08a   19%|
     |Thu  6| 07:11a  08:10p  12:59 | 09:15p  06:05a |      Rise 04:19a   11%|
     |Fri  7| 07:12a  08:08p  12:56 | 09:13p  06:06a |      Rise 05:35a    4%|
     |Sat  8| 07:13a  08:06p  12:53 | 09:11p  06:08a |      Rise 06:51a    1%|
     +------+-----------------------+----------------+-----------------------+
     |Sun  9| 07:14a  08:04p  12:50 | 09:09p  06:09a |New   Set  08:26p    0%|
     |Mon 10| 07:15a  08:02p  12:47 | 09:07p  06:10a |      Set  08:57p    2%|
     |Tue 11| 07:16a  08:00p  12:43 | 09:05p  06:12a |      Set  09:27p    7%|
     |Wed 12| 07:18a  07:59p  12:40 | 09:03p  06:13a |      Set  09:56p   14%|
     |Thu 13| 07:19a  07:57p  12:37 | 09:01p  06:14a |      Set  10:27p   22%|
     |Fri 14| 07:20a  07:55p  12:34 | 08:59p  06:16a |      Set  11:00p   31%|
     |Sat 15| 07:21a  07:53p  12:31 | 08:57p  06:17a |      Set  11:37p   41%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 16| 07:22a  07:51p  12:28 | 08:55p  06:18a |F Qtr Set  12:17a   50%|
     |Mon 17| 07:24a  07:49p  12:25 | 08:53p  06:20a |      Set  01:03a   60%|
     |Tue 18| 07:25a  07:47p  12:22 | 08:51p  06:21a |      Set  01:53a   69%|
     |Wed 19| 07:26a  07:45p  12:19 | 08:49p  06:22a |      Set  02:47a   77%|
     |Thu 20| 07:27a  07:43p  12:16 | 08:47p  06:23a |      Set  03:44a   85%|
     |Fri 21| 07:28a  07:42p  12:13 | 08:45p  06:25a |      Set  04:44a   91%|
     |Sat 22| 07:29a  07:40p  12:10 | 08:43p  06:26a |      Set  05:45a   96%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 23| 07:31a  07:38p  12:07 | 08:41p  06:27a |      Set  06:47a   99%|
     |Mon 24| 07:32a  07:36p  12:04 | 08:39p  06:29a |Full  Rise 07:51p  100%|
     |Tue 25| 07:33a  07:34p  12:00 | 08:37p  06:30a |      Rise 08:17p   99%|
     |Wed 26| 07:34a  07:32p  11:57 | 08:35p  06:31a |      Rise 08:43p   96%|
     |Thu 27| 07:35a  07:30p  11:54 | 08:33p  06:32a |      Rise 09:12p   91%|
     |Fri 28| 07:37a  07:28p  11:51 | 08:31p  06:34a |      Rise 09:44p   84%|
     |Sat 29| 07:38a  07:26p  11:48 | 08:29p  06:35a |      Rise 10:21p   76%|
     +------+-----------------------+----------------+-----------------------+
     |Sun 30| 07:39a  07:25p  11:45 | 08:28p  06:36a |      Rise 11:04p   66%|
     +-----------------------------------------------------------------------+
     * Nautical Twilight
     ** Moonrise or moonset, whichever occurs between sunset and sunrise

Ephemeris for Friday, July 28th. The Sun rises at 6:24. It’ll be up for 14 hours and 47 minutes, setting at 9:12. The Moon, 2 days before first quarter, will set at 12:18 tomorrow morning.

Tomorrow afternoon and evening will be what we call a Sun & Star Party at the Sleeping Bear Dunes National Lakeshore. This event will be at the Dune Climb. From 4 to 6 p.m., the Sun will be featured using two types of telescopes, one showing the sun’s photosphere in what we call white light, and another showing the chromosphere above it in the light of hydrogen giving a completely different view. At 6 p.m. Professor Jerry Dobek of Northwestern Michigan College and the college’s Rogers Observatory will be at the Visitors Center in Empire talking about dark skies and how to promote sensible lighting. Starting at 9 p.m. will be a star party, actually really a planet party, viewing the Jupiter early, plus Saturn, and the Moon.

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

Ephemeris for Monday, June 19th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:30, and it will rise tomorrow at 5:57. The Moon, 2 days past last quarter, will rise at 3:33 tomorrow morning.

The greatest Greek hero of all, Hercules, gets a dim group of stars on the border between the spring and summer stars. At 11 p.m. Hercules is high in the eastern sky. It is located above and right of the bright star, Vega, also in the east. Hercules’ central feature is a keystone shaped box of stars, called the Keystone, which represents the old boy’s shorts. From each top corner extend lines of stars that are his legs, from the bottom stars, the rest of his torso and arms extend. So in one final indignity he’s upside down in our sky. Just below and right of the topmost star of the keystone is what looks like a fuzzy star in binoculars or small telescope. It is the Great Hercules Globular Star Cluster, also known as M13, home to a million stars.

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

Addendum

Hercules animation showing neighboring stars, constellation outlines, deep sky objects, and constellation art for Hercules. Created using Stellarium. Click on image to enlarge.

M13, the Great Globular Star Cluster in Hercules. Credit: Scott Anttila