About Ephemeris

On June 1st, 1975 the first of a number of short programs of what became to be called Ephemeris was aired on Interlochen Center for the Arts's radio station WIAA. I have produced these programs as a volunteer effort, to help acquaint listeners to the wonders of the night, and sometimes day sky, and also to force me to keep informed as to ongoing astronomical events. What was a "little radio station in the woods" back then has grown significantly.  It has expanded facilities, and a new name: Interlochen Public Radio. It has multiple transmitters and two program formats.  See the main page for a listing of stations, times and frequencies

Here are answers to some frequently asked questions.

How did it get started?
I replied to a general solicitation given by host Chris Dicken for listeners to produce short weekly segments to run on his noon time program Bach's Lunch. Starting July 1st, 1974 I produced such a segment called Moler's Universe that lasted until the late 80's. The station then went to a format that included going on the air at 6 a.m., and they asked if I could do a short program to be aired several times in the morning with sunrise sunset and something about the sky.
Why is the program called Ephemeris?
The program actually had no name for the first 10 years or so. The favorite name Almanac was already taken. With my love for cryptic titles, I chose Ephemeris. From the Greek meaning diary, its current meaning is a collection of tables giving the positions of the sun, moon and planets at regular intervals during the year. A secondary meaning of ephemeris is astronomical almanac.
Do you get up and do your program every morning?
I couldn't do that, I'm a night person. The programs are written in batches of ten for two weeks and recorded all at once, usually on a Monday morning before 6 a.m. Once due to a really bad snow storm, a program or two were taped over the phone before 6 a.m.
How do you figure out the sunrise and sunset times?
When the program first started, the sunrise, sunset and lunar rising or setting times were interpolated from tables in the Observers Handbook, a publication of the Royal Canadian Astronomical Society for that year. Then I used similar, but more extensive tables in the American Ephemeris and Nautical Almanac. In 1981 the U.S. Naval Observatory changed the name to the Astronomical Almanac (and I was free to steal the word Ephemeris). However in 1980 I was able to program a Texas Instruments programmable calculator to produce lists of sunrise and sunset times for the year. It took 8 hours to calculate and print a years worth of sunrise or sunset times. The tapes produced would be taped to sheets for each month. The values would be transcribed to a monthly spread sheet that has the same format as the Ephemeris Calendar among these web pages. I would calculate the daylight hours. Twilight times were produced the same way as sunrise and sunset, 8 hours apiece.
Moonrise and moonset, a more complicated calculation was still done from tables. About 1982, using a small computer called a ZX81 I was able to produce automated moonrise and moonset times with a program written in Basic.
In about 1983 I was able to purchase an MS-DOS computer, though it wasn't compatible with today's computers. I wrote a program called Computed Sky, in Basic, which could display the sky from any location on earth and could print out the ephemeris page as it is seen today. Shortly afterwards I wrote Planets which I still used to produce the charts on the Planet Page. Computed Sky has been replaced in late 1992 by a new program: Looking Up, written in the C language, a program that can calculate a monthly ephemeris page in a few seconds. I also use it to create Ephemeris star charts.
How has the program changed over the years?
The format has not changed at all, really. Itused to run from 60 to 75 seconds. Starting January 2007 its cut down to 59 seconds.  The first portion of the program, about 15 seconds was devoted to the ephemeris tabular listing or calendar, which I plug values into the script. This table I use for the program is based on the location of my home, half way between Traverse City and Interlochen. Since I have a low horizon, I can spot check the times.  <Updated 1/10/07>
The second part is the topic of the day. On Wednesday this is devoted to the whereabouts of the bright planets visible to the unaided eye. In priority, the topics include events of that day or night, constellations, stars and planets visible in the evening. Last in priority is generally astronomical news of a non observational nature. These topics seem to come up more during programs when the moon is bright, drowning out the constellations.
In September 2000, I began producing Evening Ephemeris for the new station WICA.   At first they replayed the morning program.  However I wanted to keep the program completely relevant, and talking about the previous sunrise time around sunset time wasn't too cool.  So I tape two sets of programs with different part ones.   Occasionally, when the morning program covers a daytime event, a completely different evening program is written.  Starting January 1st 2007 the evening programs were discontinued due to format changes at the stations.  <Updated 1/01/07>
How do you come up with the topics you talk about?
I started to answer that above. I crank up the old word processor program and print the air dates in a column. I consult astronomical sources for events and tag the dates with those topics. The rest of the open dates get constellations, a star or planet, or news. As a planning tool the book Astronomical Tables of the Sun, Moon and Planets by Jean Meeus is invaluable for wonderful tidbits of information. Did you know that spring will not begin on March 21st for United States until the year 2103?
Other sources are The Astronomical Almanac, Sky & Telescope magazine and their Weekly News Bulletins on the Web, JPL's Space Calendar, International Astronomical Union Circulars, and running the time lapse feature of my program Looking Up to view times and appearances of planetary conjunctions, and what constellation is oriented which way in what part of the sky.
Once the topics are chosen, all I have to do is write them. I have built up an extensive library of astronomy, constellation lore and mythology. It takes about an hour to write a week's worth of programs, about two and a half pages double spaced. Anyway writer's block is less stressful with a computer with a screen saver.
Here's more than you wanted to know about me.

Comments? Email to: bob@bjmoler.org

Updated: 1/13/14