Date: June 1, 2010
Title: 35 Years Under the Stars
Podcaster: Bob Moler
Organization: Grand Traverse Astronomical Society, www.gtastro.org. Also the Ephemeris web site: ephemeris.bjmoler.org.
Description: Bob Moler has been producing the minute long Ephemeris program on Interlochen Public radio for 35 years. To celebrate that fact Bob talks a bit about the unique location he lives in and its astronomical quirks. He also explores some of the spring constellations and their stories.
Bio: Bob Moler has been an amateur astronomer since the 1950 when he was in elementary school. He has built telescopes from the mirror on up in the past, but is now using his first store-bought telescope, an 11 inch Dobsonian. He is one of the founders of the Grand Traverse Astronomical Society based in Traverse City, Michigan, and is currently its newsletter editor. Bob has produced astronomy programs on Interlochen Public Radio since 1974. This October he’s to lead a four day Astronomy Cruise on the tall ship Manitou on Lake Michigan. Pass the Dramamine.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Bob Moler, an amateur astronomer in northern lower Michigan, and volunteer broadcaster of the week-daily astronomy program, Ephemeris, on Interlochen Public for what will be 35 years this June 1st.
Hi I’m Bob Moler with 365 Days of Astronomy for Tuesday June 1st 2010. I’m an amateur astronomer in the northern part of Michigan’s Lower Peninsula who lives between Traverse City and the small village of Interlochen home to the Interlochen Center for the Arts. As of today I’ve been broadcasting minute long programs about happenings in the sky Monday through Friday on Interlochen Public Radio for 35 years. The program is called Ephemeris. The name is Latin for diary, and its also a tabular list of planet positions for specific dates. And today I start the 36th revolution of the sun with the program.
Back in 1975 the station was what I’d call the little radio station in the woods with a transmitter and antenna behind the main studio. Now IPR has a classical music station with two repeaters and a news station. They cover from Ludington 90 miles to the south to the to the Straits of Mackinaw 160 miles to the north along the shore of Lake Michigan. The original request from the station manager at the time was to give sunrise and sunset times. I added some other astronomical information. Even though the transmission pattern has grown I’ve used the same geographic point to compute those times. My house actually. We’re still close to the center of the transmission pattern.
Funny thing though, the cities of Ludington, Traverse City, Petoskey and Mackinaw City lie in pretty much of a straight line. At the winter solstice the sunrise time for each location is the same, while the sunset times vary over the period of 15 minutes. Conversely at summer solstice the sunset times are the same. while the opposite is true around sunrise.
I was already volunteering in producing a 5 minute or so weekly program for the 11 months before being asked to do the week day morning program. That program ran from 1974 to 1987. However I was spending so much time out of town on my day job, that I had to drop one of them. So I’ve been talking about the heavens a minute at a time ever since. 365 Days of Astronomy gives me the chance to explore the heavens in greater detail. I’ve been interested in astronomy just about as long as I can remember. My mother taught me the Big Dipper and the Flying “W”, of Cassiopeia. I fell in love with the constellations before getting a telescope. They have served me well.
Ok, a little detour first. A strange effect that happens from time to time if your at the right place at the right time. Or is it wrong place at the wrong time? Anyway…
Most of the amateur astronomers I know say that you can’t see Venus at midnight. That’s true as far as it goes. Venus can never be seen at an angle greater than 46 degrees from the sun, and since the earth rotates at 15 degrees an hour, Venus can never rise or set more than about 3 hours before sunrise or after sunset. However, sometimes around here that doesn’t help. The answer isn’t astronomical but political. Michigan, except the farthest western three counties in the Upper Peninsula are in the eastern time zone, whose time meridian runs through Philadelphia, Pennsylvania. During standard time my location is 43 minutes behind Philadelphia. Most of the year now in daylight time, we’re an hour and 43 minutes behind. Sunset for us today is at 9:20 p.m. Venus, the evening star now will set at 12:04 a.m. So come on over in the next week if you want to see Venus at midnight.
Midnight this time of year is about the end of astronomical twilight. So observing in dark skies is really tough if you have a day job.
So once it finally gets dark, the stars will appear. One of the things I liked to explore, especially in my older, longer program was to point out the bright constellations and tell their stories. A great source for the stories of the constellations is Richard Hinckley Allen’s Star Names Their Lore and Meaning, a Dover paperback. It’s a scholarly work, so you can take the nuggets and expand the stories on your own. It’s not really a book of stories you can read to your grand kids.
Around these parts the Big Dipper is the most famous star group, even if most folks can’t find it. As darkness falls the Big Dipper is starting to head down in the sky in the northwest. For most of Michigan the Big Dipper is circumpolar and never sets.
The Big Dipper isn’t an official constellation at all, but the hind end of Ursa Major the Great Bear. More on the bear in a bit. The Big Dipper is an asterism or informal constellation. It’s seven stars, four in the bowl and three in the handle are all, except for one, second magnitude stars the second tier of bright stars. My understanding is that the Big Dipper moniker is strictly North American. In the UK its the plough (plow), there and other parts of Europe its Charles Wain, or Charlemagne’s Wagon. It’s also a chariot, a cleaver, and in Southern France, home of Haute cuisine, it’s Casserole the saucepan.
The Big Dipper can be used to point to other stars and constellations. It’s most important pointing job for us in the northern hemisphere is to point to the North Star Polaris. We use the two stars at the front of the bowl of the dipper and extend them by 5 times their separation to Polaris. In the evening they point down. Polaris is less than an angular degree from the pole and will slowly be moving closer at least for the next hundred years. The earth’s axis wobble called precession is causing the change. It’s a slow wobble taking nearly 26,000 years to complete one circle. Polaris is at the tip of the handle of the Little Dipper which appears to be bent all wrong, or at the tip of the tail of the little bear Ursa Minor. It looks more like a squirrel to me, however. The dippers face each other bowl to handle.
Following the arc of the handle of the dipper we find Arcturus the fourth brightest night time star. Remember arc to Arcturus. This star is at the bottom corner of a kite shaped constellation called Boötes the herdsman. Extend the arc as a spike and you arrive at the bright blue-white star Spica in the constellation Virgo. Using the bowl of the dipper, we could imagine drilling a hole at the bottom to let the water leak out and it will fall on the back of Leo the lion.
Back to the Great Bear. Both the ancient Greeks and the native Americans saw a bear in the stars here. On a dark night, like tonight, especially away from city lights the rest of the stars of the bear can be seen. And it does make a remarkable lifelike bear. Except for that long tail as the handle of the Big Dipper. The native Americans saw the three stars in the handle as hunters following the bear at a distance. Check closely the middle star of the handle. Those with good eyes can spot a dim star nearby. That’s the cooking pot the hunters would cook the bear in. We know these stars as Mizar the bright handle star and Alcor the dim one. They’re also known as the Horse and Rider. The Greeks explained the long tail of the bear by saying that a god threw the beast into the sky. If you were that god, which end of the bear would you grab? I’ll give you a clue. It’s not the end with the teeth. So the tail got stretched… A lot.
Here’s the mythological events that lead up to Ursa Major being thrown into the sky where we see her today. There once was a young lady named Callisto who had a young son. Zeus, the greatest of the Greek gods liked pretty young ladies, even though he was married to the goddess Hera. Well Zeus became smitten with Callisto. Eventually Hera found out and changed pretty Callisto into an ugly bear. Many years later a young man named Arcas, who happened to be Callisto’s young son, and who never found out why his mother disappeared, happened to be hunting in the forest. Yup, you guessed it. Arcas came upon his mother and gave chase. Zeus saw what was about to happen from Mount Olympus and performed one of those maddeningly unsatisfactory solutions that the gods often did and threw both into the sky. Now Arcas as the constellation Boötes continues to chase Ursa Major, the great bear around the pole of the sky each night.
The giant planet Jupiter is named for the the chief of the Roman gods, and counterpart of the Greek Zeus. The German astronomer Simon Marius discovered Jupiter’s four large moons a few days after Galileo did. The names we call the moons are his. He gave the farthest of the four in distance from Jupiter the name of Callisto. He gave the other satellites names of Zeus’ lovers Io, and Europa and a lad Ganymede, the cup-bearer of the gods. Modern astronomers have followed Marius’ example. How about Hera and her Roman equivalent Juno. Well they’re asteroids that rarely come close to Jupiter.
I hope you’ve enjoyed these stories. As I said at the beginning of this podcast, my introduction to astronomy were the constellations and their stories. Therefore I was then well versed in the constellations before getting my first telescope to work. This helped me find my way around in the sky when I ran out of the moon and planets to view in my telescope. There’s more stories and star charts on the Ephemeris web site ephemeris.bjmoler.org including the current week’s program transcripts and mp3s. Wishing you clear skies, this is Bob Moler.
End of podcast:
365 Days of Astronomy
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