Archive for August, 2018

08/31/2018 – Ephemeris – Previewing September skies

August 31, 2018 Comments off

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.


September Evening Star Chart

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

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.


Morning twilight Evening twilight Dark night Moon
Date Astronomical Nautical Nautical Astronomical Start End Illum.
2018-09-01 5h26m 6h04m 21h28m 22h06m 22h06m 23h43m 0.68
2018-09-02 5h27m 6h05m 21h26m 22h04m 22h04m 0.57
2018-09-03 5h29m 6h07m 21h24m 22h02m 22h02m 0h22m 0.46
2018-09-04 5h30m 6h08m 21h22m 22h00m 22h00m 1h08m 0.34
2018-09-05 5h32m 6h09m 21h20m 21h58m 21h58m 2h04m 0.23
2018-09-06 5h33m 6h11m 21h18m 21h55m 21h55m 3h08m 0.14
2018-09-07 5h35m 6h12m 21h16m 21h53m 21h53m 4h19m 0.06
2018-09-08 5h36m 6h13m 21h14m 21h51m 21h51m 5h35m 0.02
2018-09-09 5h38m 6h15m 21h12m 21h49m 21h49m 5h38m 0
2018-09-10 5h39m 6h16m 21h10m 21h47m 21h47m 5h39m 0.01
2018-09-11 5h41m 6h17m 21h08m 21h44m 21h44m 5h41m 0.06
2018-09-12 5h42m 6h19m 21h06m 21h42m 21h57m 5h42m 0.12
2018-09-13 5h44m 6h20m 21h04m 21h40m 22h27m 5h44m 0.21
2018-09-14 5h45m 6h21m 21h02m 21h38m 23h01m 5h45m 0.3
2018-09-15 5h47m 6h22m 21h00m 21h36m 23h37m 5h47m 0.4
2018-09-16 5h48m 6h24m 20h58m 21h34m 5h48m 0.5
2018-09-17 5h49m 6h25m 20h56m 21h32m 0h18m 5h49m 0.6
2018-09-18 5h51m 6h26m 20h54m 21h29m 1h03m 5h51m 0.7
2018-09-19 5h52m 6h28m 20h52m 21h27m 1h53m 5h52m 0.78
2018-09-20 5h54m 6h29m 20h50m 21h25m 2h47m 5h54m 0.86
2018-09-21 5h55m 6h30m 20h48m 21h23m 3h45m 5h55m 0.92
2018-09-22 5h56m 6h31m 20h46m 21h21m 4h44m 5h56m 0.92
2018-09-23 5h58m 6h33m 20h44m 21h19m 5h45m 5h58m 0.96
2018-09-24 5h59m 6h34m 20h42m 21h17m 0.99
2018-09-25 6h00m 6h35m 20h40m 21h15m 1
2018-09-26 6h02m 6h36m 20h38m 21h13m 0.99
2018-09-27 6h03m 6h37m 20h36m 21h11m 21h11m 21h12m 0.95
2018-09-28 6h04m 6h39m 20h35m 21h09m 21h09m 21h44m 0.89
2018-09-29 6h06m 6h40m 20h33m 21h07m 21h07m 22h21m 0.81
2018-09-30 6h07m 6h41m 20h31m 21h05m 21h05m 23h04m 0.72

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),

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
     |      |  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


Categories: Uncategorized

08/30/2018 – Ephemeris – Planet controversy again

August 30, 2018 Comments off

Ephemeris for Thursday, August 30th. The Sun will rise at 7:02. It’ll be up for 13 hours and 20 minutes, setting at 8:23. The Moon, 3 days before last quarter, will rise at 10:40 this evening.

Back when I was a kid we used to know what a planet was, and there were 9 of them. Back then there was no real definition for a planet, other than it orbited the Sun. You knew it when you saw it. In 2006 the International Astronomical Union voted to define planets by three criteria, which left Pluto out, so now there are 8. Planetary scientists, who may not consider themselves astronomers, balk at that definition. Alan Stern of the New Horizons mission to Pluto wants a new definition. Basically a planet is any body that’s round, or formally has reached hydrostatic equilibrium. That includes all 9 old planets, many moons like ours, Kuiper Belt objects, and the asteroid Ceres. About 115 at last count.

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


For more information go to Ethan Siegel’s Starts with a Bang blog:  You Won’t Like The Consequences Of Making Pluto A Planet Again

Categories: Planets

08/29/2018 – Ephemeris –

August 29, 2018 Comments off

Ephemeris for Wednesday, August 29th. The Sun will rise at 7:01. It’ll be up for 13 hours and 23 minutes, setting at 8:24. The Moon, 3 days past full, will rise at 10:13 this evening.

It’s our Wednesday look at the bright planets. Four of them are visible in the evening sky. The brilliant Venus will be visible in the western twilight from about 8:40 p.m. until it sets at 9:44 p.m. Jupiter will be in the southwest as it gets dark. It is only outshone by Venus, the Moon, and currently Mars. Jupiter will set at 11:05 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 9:21 p.m. and will set at 1:47 a.m.. Mars will be low in the southeast as the skies darken tonight. and is now 41.3 million miles (66.6 million km) away. It will set at 3:25 a.m. Mercury will rise in the east-northeast at 5:29 a.m. and be visible until about 6:40 tomorrow morning.

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


Evening planets

The evening planets visible at 9 p.m., almost an hour after sunset. August 29th, 2018. Click on the image to enlarge. Created using Stellarium.

Telescopic evening planets

Venus, Jupiter, Saturn and Mars with the same magnification at 9 p.m. August 29, 2018. Mars is also shown enlarged. The global dust storm is abating, so the albedo features are beginning to be seen. Created using Cartes du Ciel (Sky Charts).

Mercury in the morning

Mercury seen at 6:15 a.m. August 30, 2018, about 45 minutes before sunrise. Bonus Orion appears without the possibility of frostbite. Click on the image to enlarge. Created using Stellarium.

Binocular Moon

The gibbous Moon as it should appear tomorrow morning. Created using Stellarium.

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on August 29, 2018. The night ends on the left with sunrise on the 30th. Click on the image to enlarge. Created using my LookingUp program.

08/28/2018 – Ephemeris – Water on the Moon

August 28, 2018 Comments off

Ephemeris for Tuesday, August 28th. The Sun will rise at 7:00. It’ll be up for 13 hours and 26 minutes, setting at 8:26. The Moon, 2 days past full, will rise at 9:47 this evening.

Ten years ago India launched its lunar orbiting Chandrayaan-1 spacecraft. On it was a NASA instrument the Moon Mineralogy Mapper to study the composition of the Moon’s crust. With it they discovered signatures of water at the Moon’s high latitudes, probably in water-bearing minerals. Water was also confirmed in craters near the Moon’s south pole by the LCROSS probe that was launched with the Lunar Reconnaissance Orbiter in 2009. It crashed near the Moon’s south pole in a crater following a centaur stage which it was observing. Though the expected visual show wasn’t visible from Earth the LCROSS satellite saw and returned its observations before it too crashed. It relayed that the Moon had ice near the south pole.

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


Water Detected at High Latitudes on the Moon

Water Detected at High Latitudes on the Moon by the Moon Mineralogy Mapper The water-bearing minerals are colored blue. Credit ISRO/NASA/JPL-Caltech/Brown Univ./USGS

Map of water at the Moon's poles

The Moon’s south pole area on the left and north pole on the right. The cyan color shows shadowed areas where ice is located. From data gathered by the Moon Mineralogy Mapper, and instruments on the Lunar Reconnaissance Orbiter, and LCROSS. Click on image to enlarge. Credit NASA.

Finding water is a big deal.  It helps Moon colonists live off the land, so to speak.  While the poles on Earth are foreboding places, those of the Moon could give colonists an advantage.  First, that’s where the water is.  The Moon has very little axial tilt so deep craters never see the sunlight, and high peaks see eternal sunlight, a great place to place solar panels for just about continuous energy production.


08/27/2018 – Ephemeris – It wasn’t the Harvest Moon but it has that effect

August 27, 2018 Comments off

Ephemeris for Monday, August 27th. The Sun will rise at 6:59. It’ll be up for 13 hours and 29 minutes, setting at 8:28. The Moon, 1 day past full, will rise at 9:21 this evening.

Last night’s full moon wasn’t the Harvest Moon. That’s next month’s full moon. This full moon is the Sturgeon Full Moon. You’d think it should be the Corn Moon, That’s normally the September’s full moon, which is preempted this year by the Harvest Moon, the closest full moon to the autumnal equinox. What’s taking effect now is what I call the harvest moon effect, in that the nearly full Moon stays in the evening sky for almost a week, it seems, after full; while I’m waiting to spot the wonders of the summer Milky Way at a decent hour. On average the Moon rises about 50 minutes later each night. Now it’s decreasing to be less than 30 minutes. It won’t be until Thursday night that we’ll have a whole half hour of dark skies, and up to an hour by Friday night.

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


Harvest Moon Effect

The motion of the Moon with respect to the eastern horizon from August 27 through August 31, 2018. It shows the difference in the rise times that create the harvest moon effect. Created using Cartes du Ciel (Sky Charts).

08/24/2018 – Ephemeris – The last Friday Night Live of the year is tonight

August 24, 2018 Comments off

Ephemeris for Friday, August 24th. The Sun rises at 6:55. It’ll be up for 13 hours and 37 minutes, setting at 8:33. The Moon, 2 days before full, will set at 5:54 tomorrow morning.

The Grand Traverse Astronomical Society will be at the last Friday Night Live of the year tonight on Front Street in Traverse City. We have a lot of fun at these events, looking at the Sun and possibly Venus from 5:30 p.m. to 9 p.m., talking astronomy and what’s up in the sky, and NASA’s missions to the planets and now the Sun. After 9 p.m. if it’s clear we pull our telescopes off the street and onto the sidewalk to view the planets Jupiter, Saturn and Mars. Last week we had the Moon, but it’s no longer in the southern sky in the evening. Last week we didn’t pack our telescopes up until after 11 p.m. But it all depends on the clouds. Our next sidewalk event will be October 20th, International Observe the Moon Night.

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


Looking at the Moon

A girl looking through a telescope at the nearly first quarter Moon at Friday Night Live, August 17, 2018.

Friday Night Live

Looking down Front Street in Traverse City at the Friday Night Live August 17, 2018.

08/23/2018 – Ephemeris – Mercury’s morning appearance

August 23, 2018 Comments off

Ephemeris for Thursday, August 23rd. The Sun rises at 6:54. It’ll be up for 13 hours and 40 minutes, setting at 8:35. The Moon, 3 days before full, will set at 4:56 tomorrow morning. | The tiny and elusive planet Mercury is making an appearance in the morning sky now. On Sunday afternoon our time Mercury will at its greatest elongation or separation west of the Sun. So Sunday or Monday mornings are the very best time to spot it. Look to the east-northeast at a low horizon to spot it. It should be visible from about 6 a.m. to about 6:40 a.m. before twilight swamps it. There are no stars of comparable brightness near it. It’s seen against the dim stars of Cancer the crab. The bright stars Pollux and Castor of Gemini will appear a ways above it. It should be visible from now through next week. Today is the day of the mini-Moon, its smallest of the month at 252 thousand miles (406 thousand km) away.

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


The motion of Mercury

The motion of Mercury from August 23 to September 1, 2018. For each day the magnitude of Mercury is given. Note that gets brighter over the period. That is the magnitudes get more negative. The is due to Mercury’s increasing phase, getting fuller as it moves around the Sun. Created using Cartes du Ciel (Sky Charts).

Categories: Ephemeris Program, Mercury