Navigating by Astronomy
Introduction and Contents
Copyright © 2017 Travis N. Wood
WHY USE ASTRONOMY?
Most methods of finding north in the wilderness rely to some extent upon astronomy. Compass or GPS are the notable exceptions. But even the legendary moss on the north side of trees would depend for its veracity upon astronomical phenomena, in that case, the movements of the sun.
So why use astronomy when we have GPS units, compasses, topographic maps, and sometimes well-marked trails to follow? And if we are going to use astronomy, why not simply rely upon the North Star?
First, does your GPS tell you where the sun will rise when setting up camp in the backcountry? Despite the high-tech devices, we still hear backpackers reciting, "The sun rises in the east and sets in the west." But unless we are treating half the sky as east and half the sky as west, we may be very mistaken. Astronomy will better inform us.
As backpackers we seek out the primitive world and dabble in survival. In mid-2016 we read a popular backpacking magazine rely on the notion that the sun was south at noon. Regardless of page after page devoted to selling high-tech gear, the publication fell back upon a couple old adages, as if common sense. But even basic astronomy shows us that the sun is rarely south at noon.In reality, it is rare for the sun to rise due east. And it is rare for the sun to be directly south at noon. Often those statements are so inaccurate that we would never rely upon a GPS or compass that misled us so badly.In our area of interest here, from Yellowstone, the Beartooths, and the Wind River Range and eastward to the Bighorn Mountains, the Black Hills and the Badlands of South Dakota, the sun could rise anywhere within an arc of almost 70° azimuth. It may not be E on your compass but rather closer to NE or SE. And where the sun will be at noon could be almost as large a variety of directions.
Secondly, in regard to the North Star, it can be an aid to finding north — if it is clearly visible among the forests, mountains, and clouds that can obscure our vision at nighttime in the backcountry. But relative to other stars, the North Star is dim. To identify it with assurance, other stars nearby must first be located. Most of us learned to find the Big Dipper and use it to find the North Star. That may work if the Big Dipper is not obscured and we are camped in a stationary location. But we must first wait until the skies are dark. And that still does not tell us where the sun will rise, how to orient our tent for first daylight, and so on.
Beyond the fixed campsite, if we are actually hiking at night, we will navigate by repeatedly checking our directions. That may be done much more easily with a brighter star, and if the North Star or Big Dipper are obscured at times, we may be rather helpless if we don't know how to use other stars, the moon, or even planets for direction.
The skies are a great wilderness. As wilderness explorers on earth, it is in our interest to study and carry maps, though the maps we carry may be simple pieces of folded paper. Our maps likely rely upon high-tech sources. So it is with our maps of the celestial wilderness. Whether a topo map of the Wind River Range or a simple chart of the stars, we benefit from satellites and high-tech science.
So we include here a few sources to aid our research into the wilderness above us. There are several free astronomy programs that can be downloaded from the Internet. I'll mention just a couple I'm most familiar with. We can learn from those tools though we leave them behind. Finally, perhaps the most valuable high-tech tool we may include is an accurate watch. As we'll show, it can be a lightweight tool for precision. Yet the more familiar we become with the celestial sphere, the more we learn that not even a time-piece is always necessary.
Free Software Without Malware:
The US Naval Observatory also provides a star chart and detailed tabulations of coordinates of sun, moon, planets and so on. We can use these sources and software to check our work, but we wish here to understand the principles behind the raw data because we are not likely to have a computer with us in the wilderness.
WHERE THIS BEGAN
When I've mentioned finding direction by the sun, moon or stars, I've had folks ask, "Were you a boy scout or something?" Not at all. I was introduced to these ideas nearly 30 years ago through a book called simply Bushcraft by Richard Harry Graves. Graves (1898-1971) was a commanding officer of US Army Air Force search and rescue in the Australian bush during World War II. His books are classics in backcountry survival. I practiced his methods through two years of weekly night hiking and for decades following, using his tools day and night to navigate wilderness areas solo.
Of course, I've also used GPS, topo maps, compasses, and several other methods of finding direction in the wilderness. Each method has advantages and disadvantages — as does astronomy. But if you find yourself pitching a tent in the wilderness on a cool evening, with the idea of catching the next morning's first rays of sunshine, you'll be sadly disappointed after reciting, "the sun rises in the east and sets in the west." It may not. So when your tent is still hidden from the sun at morning's first light, perhaps you'll acknowledge that you've missed something important about what happens in the skies above you.
We hope to remedy that situation here. What we'll show here is that astronomy, from daytime sun to nighttime moon, stars, and planets, can be one of the most efficient, accurate, and reliable methods of determining direction. And knowing that the sun does not always set "in the west" may be a crucial element of knowing how to survive in an emergency.From the simple question of "Where does the sun really set?" astronomy can involve some tedious calculations and concepts difficult to visualize. We'll try to avoid the obscure and focus on simplicity as best we can find it.
Southing Altitudes, Azimuths of Rising/Setting, Time Above Horizon
Copyright © 2017 Travis N. Wood