Hot Tub Astronomy: Navigating the Celestial Hot Tub Mar10


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Hot Tub Astronomy: Navigating the Celestial Hot Tub

Printed in Astronomy Magazine, March 1992

After much careful thought, we enrolled in our local college’s class on celestial navigation. But why?

We soon noticed that our fellow students either already owned yachets capable of sailing at least to Hawaii, or had been building a boat for years and now, about finished, were eager to embark on long dreamed cruises to the unknown. A couple of hearty young men had obtaineed good paying jobs on fishing boats. Most all had perfectly logical reasons to be in this class.They were preparing themselves for possible life and death struggles with the open sea.

On the other hand our two very small boats, lying on the sand below our deck (one a row boat for fishing, the other a catamaran, sort of a beat up trampoline with pontoons) were clearly meant for staying fairly close to shore. If we should find ourselves in need of navigation for either, we would definately require the services of the Coast Guard. So why were we spending two nights a week studying celestial navigation? I think it was the word Celestial. It has such a nice ring to it. So Bob and I decided to enroll. I reasoned: You never knew when we might be tempted to take a Love Boat Cruise. Remember the Titanic!

The first thing I noticed after paying the tuition and investing in the books and equipment, was that the three very large textbooks seemed to contain more letters than numbers. Oh, oh… this is going to be a long semester! I’m not a number person. The best thing was that celestial navigation lent itself very well to hot tub study. Maybe it wouldn’t be so bad after all.
Luckily we found ourselves in the hands of an excellent teacher, who had years of experience sailing around the world and an inexhaustible supply of breathtaking sea stories. And a way of making us all understand the importance of studying well.
The first thing we learned was that from now on we had to suspend belief in all that we had learned about astronomy From this day on the Earth is the center of the Universe, and all bodies, the Sun, the Moon, Planets, and Stars are all rotating around us. We were all now on the Terrestrial Sphere and all else was on the Celestial Sphere. What we would learn to do is measure the distance of a given star or planet above the horizon. We would accomplish this with the help of newly issued sextants and our copies of the Nautical Almanac. By finding the star on our charts and plotting its altitude, we could determine just where on Earth we were. Sounds simple enough!

Failing that, our teacher said, “You can always use the butter method to get to Hawaii.” With all the curious eyes on him, He continued. “Take the butter out of the icebox, set it on the counter and sail south until the butter melts, then turn right, and Presto! Hawaii!”

After learning a host of new terms and our way around the gadgets on the sextant, we were taught how to shoot the Sun at meridian passage (high noon) and to sight the moon. We accomplished this by standing on the rocks by the nearby jetty, and often from the school sail boat, a beat-up craft, apparently sea worthy, donated to the school. Soon we were, hopefully, ready to sight the stars.

W climbed a board the good ship “Hot Tub” a little early the next night, anxious to try on our own. Our Nautical Almanac contained a chart for each day of the year, and on this day’s chart we found the time of the end of civil twilight in our latitude, that’s when the sun is six degrees below the horizon. At that time we must be prepared to take our star’s sighting.Before that time it’s too light to see the stars and very soon after it;s too dark to see the horizon.

At this time that I used to simply call, sunset, I sat comfortably warm in the bubbling water, and adjusted the mirrors on my little plastic sextant, thinking all the while of those intrepid explorers who struggled aboard heaving ships, constantly fighting the wind, cold and salty spray as they worked their way across the oceans. This funny little sextant must have been very badly needed, for it was invented similtaneously in England and America in 1735.

I was fiddling with the mirrors, trying to determine possible sextant error by looking at the split in the horizon (the two images had to coincide) I slowly and carefully brought the image of Sirius down to the edge of the water. “Mark!” I punched the the stopwatch. When the book says “time”, it means the exact time to the second. That means learning how many seconds your watch is off from the time signal from the Atomic clock in Washinton D.C. WWV.

Next I turned on my flashlight and squinted to read the delicate altitude numbers etched on the sextant. After writing these things on my sight reduction chart, I waited for the next star. I already knew it would be Betelegeuse, followed by Rigel. Orion hovered in its celestial location. The plotting would be done later at the kitchen table. I hoped the sightings would show that we were some place close to 33 degrees, 27 minutes west 117 degrees, 41 minutes north—our known position.

Actually, I was disapointed. My sightings moved our hot tub about a mile inland, with no view of the ocean. However our teacher said that in the middle of the Pacific Ocean, that was a passable sighting. This class was very enjoyable, even for a semi-landlubber.

Next, we decided, we will sign up for the class in “Pilot Ground School”, even though we don’t have an airplane. Bob flew C47 transports in World War ll. When you’re retired you can do whatever you find interesting, Right?


That was twenty years ago. We took the Pilot ground school and really enjoyed it. It was taught by an ex-Navy Jet Jockey, who was very knowledgeable. I was in way over my head, but Bob tutored me along and the teacher was very tolerant of those in the class who had no intention to actully fly. When it came to the final exam, I paid close attention to my husband, tutor, experienced pilot and memorized all he taught me. Then a funny thing happened. I got all of the questions right and Bob missed one!

I aked him how that could happen, when all of my answers came directly from him. He said he got to thinking about one and changed… “Oh so that’s it. you understood it and could think about it. I know nothing except what you taught me and could not think about it at all.”

The late 2000’s found our son, J.R. and family living in a Texas Airpark with a hanger in back of the house and a cute little plane inside. And one of our daughters, Pam, now a grandmother with her pilot’s license, part of a flying club with planes and a member of the Civil Air Patrol.

What we took for fun! They took seriously! Hooray!

Watch for the next hot tub story, “The mystery of the Red and Green Lights