This is the companion Web Site of Bob Moler's Ephemeris radio program, which is broadcast Monday Through Friday on Interlochen Public Radio Stations. Interlochen Public Radio serves northwestern lower Michigan. The first Ephemeris program was broadcast June 1, 1975.

Click on the above link for live streaming audio from IPR. Or download the Interlochen Public Radio app from the Apple App Store or Google Play.

Bob Moler's Ephemeris Blog contains scripts and illustrations for the Ephemeris programs. They are generally released at 12:01 a.m. Eastern Time on the program play date.

NASA/JPL Solar System Ambassador


Contact me at the email address at the bottom of this page to discuss star parties and presentations for schools, scout groups, and non-profit organizations.


That being said, opinions expressed on this website are my own and not that of NASA or JPL

Ephemeris Radio Schedule Monday - Friday

Ephemeris air times (ET)

6:19 & 8:19 a.m. - News stations

7 a.m.- Classical stations

The Stations of Interlochen Public Radio


WIAA 88.7 FM* Interlochen

94.7 FM Traverse City

WIAB 88.5 FM Mackinaw City


WICA 91.5, FM Traverse City

WLNM 89.7 FM Manistee

WHBP 90.1 FM Harbor Springs, Petoskey

Observing Weather in Northwestern Lower Michigan

Clear Sky Chart from Attilla Danko
NWS Traverse City Forecast.
Gaylord, MI Weather Radar.
Canadian based Infrared Satellite (GOES-East data) Michigan shows best in the Eastern Canada view
GOES-East - Sector Views: Great Lakes - GeoColor

On this site – articles of interest for this month

Sightseeing Around the Summer Triangle It’s still up in early Autumn

Some Autumn Binocular Sights

September Song

The Great Star Story of Autumn

Autumn Telescopic Wonders

September 2020

Interested in learning more? If you live in northwestern lower Michigan check out the Grand Traverse Astronomical Society.

More information on visible planetary and other events are available on Bob Moler's Ephemeris Blog the day of the event. The blog contains Monday-Friday program transcripts, most with illustrations and additional information.

I dug through the IPR web archives and found these:

Bob Moler looks back at 40 years of 'Ephemeris'

I’m interviewed about all things astronomical prior to the August 21, 2017 eclipse. Photo, text, and audio.


Extra! My report on the Great American Eclipse of August 21, 2017, with added animated GIF of the sky at the totally eclipsed Sun, watching the shadow pass over.

Highlights for September 2020 (ET)

   Date      Time    Event
Sep 1  Tu            Venus: 44.7° W
    2  We  01:22 am  Full Moon
    6  Su  12:42 am  Moon-Mars: 0°
    6  Su  02:31 am  Moon Apogee: 405,600 km
   10  Th  05:26 am  Last Quarter
   10  Th  07:05 pm  Moon Ascending Node
   11  Fr  03:15 pm  Neptune Opposition
   12  Sa  01:25 am  Moon North Dec.: 24.4° N
   12  Sa  08:10 pm  Venus-Beehive: 2.6° S
   13  Su  11:19 pm  Moon-Beehive: 1.9° S
   14  Mo  12:43 am  Moon-Venus: 4.6° S
   17  Th  07:00 am  New Moon
   18  Fr  09:44 am  Moon Perigee: 359,100 km
   22  Tu  02:06 am  Mercury-Spica: 0.3° N
   22  Tu  09:31 am  Autumnal Equinox
   23  We  08:33 am  Moon Descending Node
   23  We  09:55 pm  First Quarter
   24  Th  03:11 pm  Moon South Dec.: 24.5° S
   25  Fr  02:46 am  Moon-Jupiter: 1.7° N
   25  Fr  04:46 pm  Moon-Saturn: 2.5° N
Oct 1  Th            Venus: 40.3° W

NASA - SKYCAL - Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA's GSFC) (with occasional annotations and additions) It can also generate in a calendar page format.

September Preview post from my blog:

Active Planetary Space Missions

We have a new location for information on planetary space missions. It's here at the Planetary Society. The chart is created by Olaf Frohn, and is updated every month.

Free Software

Stellarium is a fabulous planetarium program with a very realistic sky and simple controls.

They've added some features in the latest version (0.20.2) and and a new rendering engine that may not be compatible with computers more than a year or two old without using command line options. See the Stellarium User Guide (pdf) under Command Line Options for options to try. My older laptop requires “-a”.

There’s also a web based version of Stellarium. It’s pretty much bare bones, but works much like the computer version. It’s located here:

Cartes du Ciel (Sky Charts) is a great telescope companion. I use it to create finder charts for comets and calendar lists of twilight times for the monthly preview on my blog. It can be downloaded from

Virtual Moon Atlas is a great tool for reference at the telescope or desk.

Celestia is a great 3D simulator of solar system objects and beyond.

Hallo Northern Sky is an interesting planetarium program. It seems not as polished as Stellarium, but has some cool features. I use it when planning star parties as a quick way to see what would be visible because it loads quickly.

Years on the air: 44

Years on the Internet: 25


Updated: 09/07/20