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.

Click here for mp3 audio of the current batch of Ephemeris programs

Bob Moler's Ephemeris Blog contains transcripts and illustrations from 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.


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 a.m. - News stations

6:59 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

WICV 100.9 FM East Jordan, Charlevoix


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.
Satellite Infrared Loop.
Canadian based Infrared Satellite (Michigan shows best in the Eastern Canada view)

On this site – articles of interest for this month

A Hairy Constellation

The Spring Cat - Leo

Looking Out

South Spring Skies

Exploring Spring Deep Sky Objects

The Skies of Spring

April 2017

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.

Highlights for April 2017 (ET)

   Date    Local Event
Apr 01  Sa       Venus: 13.4° W
    01  Sa 04:49 Moon-Aldebaran: 0.3° S  Occultation Asia
    01  Sa 05:59 Mercury Greatest Eastern Elongation: 19°
    03  Mo 02:12 Moon North Dec.: 19° N
    03  Mo 14:39 First Quarter
    05  We 08:45 Moon-Beehive: 4° N
    07  Fr 00:30 Moon-Regulus: 0.8° N
    07  Fr 05:14 Moon Ascending Node
    07  Fr 16:58 Jupiter Opposition from the Sun
    10  Mo 17:20 Moon-Jupiter: 2.4° S
    11  Tu 02:08 Full Moon
    14  Fr 01:43 Uranus Conjunction with the Sun
    15  Sa 06:05 Moon Apogee: 405500 km
    16  Su 14:39 Moon-Saturn: 3.6° S
    17  Mo 09:12 Moon South Dec.: 19.1° S
    19  We 05:57 Last Quarter
    20  Th 01:46 Mercury Inferior Conjunction with the Sun
    21  Fr 04:16 Mars-Pleiades: 3.5° S
    21  Fr 18:30 Moon Descending Node
    22  Sa 07:40 Lyrid Meteor Shower: ZHR = 20
    23  Su 13:59 Moon-Venus: 5.3° N
    26  We 08:16 New Moon
    27  Th 12:18 Moon Perigee: 359300 km
    28  Fr 13:20 Moon-Aldebaran: 0.5° S Occultation daytime
    30  Su 09:33 Moon North Dec.: 19.2° N
May 01  Mo       Venus: 39.9° W

NASA - SKYCAL - Sky Events Calendar by Fred Espenak and Sumit Dutta (NASA's GSFC) (with occasional annotations)

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. The newest version , 0.15.2 is the current beta release.

If you have an older computer download 0.12.8, which may work better for you. They've added some features in the latest version (0.15.n) and and a new rendering engine that may not be compatible with computers more than a year or two old.

Cartes du Ciel (Sky Charts) is a great telescope companion. Version 4.0 came out in March 2016. You can download it 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.

Years on the air: 41

Years on the Internet: 21


Updated: 03/31/17