Natural  Navigation  

     

 

Natural Navigation

Jazmine Gaona

ASTR 1050

Ray Oltion

April 15, 2013

Photo Credit: http://www.universetoday.com  

   Natural  Navigation  

     

Introduction When you’re lost, what do you do? Most of us rely on our smart phone or

GPS device to navigate us to our desired location. But, have you ever pondered

how humans used to navigate before such technology? Perhaps you’ve thought

about natural navigation techniques, and how they were applied. Humans have

been using the stars, sun, and man-made inventions to get around the planet

ever since the inception of travel.

Since the beginning of time, humans wanted to travel the Earth; however,

they needed to know where they were going. By trial and error they discovered

several natural navigational tools. They started using the night sky, and gave

close attention to the stars as they illuminated the sky. Locating Plough, Polaris,

Cassiopeia, Orion, and Mintaka greatly helped individuals navigate at night.

Polaris, the current North Star, didn’t seem to move as much as the others, and

eventually became the beacon for night travelers. The sun can also be used to

navigate, but requires precise time measurements. Eventually, this led to the

invention of several inventions including: the gnomon, the Arabian Kamal, the

astrolabe, the cross-staff, the back-staff, the sextant, and the lunar distance

method.

Navigation Using The Stars

“Sailors from the Phoenicians to the Polynesians knew the heavens

remained the best way to find one’s north-south positions” (Secrets of Ancient

Navigators). By locating Plough (the big dipper), and Polaris (the north star),

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Cassiopeia, Orion, and Mintaka humans were able to navigate their way around

the world.

Plough & Polaris

The Big Dipper, formally known as Plough or Ursa Major, is an excellent

tool located in the twinkling night sky that can be used to help navigate. To do

this, first find the ‘pointer’ stars, the two stars that a liquid would run off if you

tipped up the ‘saucepan’.

These two stars will lead you

to Polaris. Polaris, commonly

known as the North Star, is

directly above true north.

This star is the end of the

‘handle’ on the Little Dipper

or Ursa Minor. The North

Star will always be five times

the distance between these two pointers on the Big Dipper, in the direction that

they point (up and away). The Big Dipper rotates counter-clockwise about the

North Star, so it will sometimes appear on its side or even upside down.

However, its relationship with the North Star never changes and it will always

dependably point the way. Also, the elevation of Polaris directly corresponds to

the observer’s latitude between the North Pole and the equator. When the

observer gazes from 90 degrees latitude, the North Pole, Polaris would be

Photo Credit: http://www.universetoday.com  

   Natural  Navigation  

     

located directly overhead at an altitude of 90 degrees. Therefore, if the observer

stood at zero degrees latitude, Polaris would be located on the horizon at exactly

zero degrees altitude. “In ancient times, the navigator who was planning to sail

out of sight of land would simply measure the altitude of Polaris as he left

homeport, in today’s terms measuring the latitude of home port. To return after a

long voyage, he needed only to sail north or south, as appropriate, to bring

Polaris to the altitude of home port, then turn left or right as appropriate and ‘sail

down the latitude,’ keeping Polaris at a constant angle” (The History of the

Sextant).

Cassiopeia

Occasionally Plough isn’t as easy to

find, because it is low in the sky or

obscured. In this case, Cassiopeia is helpful

in finding the North Star. Cassiopeia is

always on the opposite side of the North

Star from the Big Dipper.

Orion & Mintaka

Orion’s Belt or the Belt of Orion is

a useful constellation that can be used

to help navigate east and west. Orion’s

Photo Credit: http://www.universetoday.com

Photo Credit: http://www.universetoday.com

 

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belt, the only three bright stars that form a short straight line in the whole night

sky, rise very close to due east and set very close to due west. Mintaka is the

first star in the Orion belt to rise and set. This star always rises and sets within

one degree of true east and west wherever you are in the world.

Navigation Using The Sun

Many individuals believe

that the sun rises in the east,

and therefore it is a clear

indicator of where east is

located. However, this belief is

simultaneously right and wrong.

In reality, the sun rises due east

on only two days of the year, the equinoxes, near March 21 and September 22.

This is due to the tilt of the Earth as it travels around the sun. On midsummer’s

day in the northern hemisphere, around June 21st each year, the summer

solstice, the North Pole is tilted as much as it ever will be towards the sun. On

midwinter’s day, around December 22 each year, the winter solstice, the South

Pole is tilted as much as possible towards the sun.

How To Use The Sun To Navigate

At midday, the shortest shadow

cast by a stick each day will form a

Photo Credit: http://www.naturalnavigator.com

Photo Credit: http://www.naturalnavigator.com

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perfect north-south line anywhere in the world. By marking the tip of a stick’s

shadow over the course of the middle part of the day, a curve is made. “To get

an exact north bearing, mark the shadow every few minutes for a hour or so

spanning noon (1pm in summer) and determine where the shortest shadow is”

(Natural Navigation). The closest point on this curve to the stick will be a perfect

north/south line.

Navigation Using Inventions

After centuries of navigating by using the stars and suns, increasingly

sophisticated instruments were invented. Many of these devices measure the

height of the sun and the stars over the horizon.

The gnomon

The gnomon is a sun-shadow disk that

enables the user to determine their latitude

by the length of the sun's shadow cast on a

disk. It can be used for finding the declination

of the sun through the year. It is one of the

first scientific instruments ever made,

originating with the Chaldean astronomers of

Babylon and from there brought to the Greek world. The ancient Babylonians

stuck the gnomon on a stone and, voila, created the sundial.

Photo Credit: http://mysite.du.edu

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The Arabian Kamal

The Arabian Kamal is a rectangular plate that determines latitude. It is

used by moving closer or farther from one's face until the distance between the

North Star and the horizon exactly

corresponded to the plate's upper and

lower edges. The distance the plate

lay away from the face, measured by

a string tied to the center of the plate

and held at the other end to the tip of

the nose determined the latitude.

“Notice the knots in the cord attached to the carved mahogany transom. Before

leaving homeport, the navigator would tie a knot in the cord so that, by holding it

in his teeth, he could sight Polaris along the top of the transom and the horizon

along the bottom. To return to homeport, he would sail north or south as needed

to bring Polaris to the altitude he’d observed when he left home, then sail down

the latitude” (Secret’s of Ancient Navigators). The device originated with Arab

navigators of the late 9th century, and was employed in the Indian Ocean from

the 10th century.

Astrolabe

The astrolabe is a disc of metal that

one held suspended by a small ring.

Photo Credit: http://airandspace.si.edu

Photo Credit: http://www.saudiaramcoworld.com

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Astronomers, navigators, and astrologers historically used it. The disc had a

scale with degrees and a ruler for measuring the height of an astronomical body.

“The astrolabe was popular for more than 200 years because it was reliable and

easy to use under the frequently adverse conditions aboard ship” (Tools Used in

Celestial Navigation and its History). It predicted the positions of the sun, moon,

planets, and stars, to determine the local time given the local latitude, and vice-

versa.

Cross-staff

The cross-staff was introduced in

England in the mid-sixteenth century as

a common navigational instrument. It

was designed to measure the angles

between stars, and to measure the

heights of structures or topographical

features such as mountains and hills. It is

a long staff with a perpendicular vane, which slides back and forth. The device is

t-shaped, and the base is held up to ones eye. The suns height is measured by

pulling the slide-able top of the T toward one's eye until the sun lay at the top and

the horizon at the bottom. The staff is marked with graduated measurements --

calculated by trigonometry. Although it was an effective invention, it had two

major problems. “Because the device also determined the altitude of the sun, the

user was required to look directly into the blinding sun” (Secrets of Ancient

Photo Credit: http://astronomy.swin.edu.au

   Natural  Navigation  

     

Navigators). Also, the observer had to look in two directions at once - along the

bottom of the transom to the horizon and along the top of the transom to the sun

or the star” (The History of the Sextant). This made the device difficult and

dangerous to use; therefore, the back-staff was developed.

Back-staff

The back-staff was invented in

1595 by the English explorer John

Davis. The back-staff eliminated the

problems of parallax and glare of sun

sights. The invention enabled users to

get the same measurement as the

cross-staff, but with one's back to the

sun. “To use the device, the observer

would place the device on ones

shoulder and stand with their back to

the sun with the horizon vane lined up with the horizon. The half-cross would

slide back and forth until the shadow of its vane fell across the slit in the bottom

vane, while the horizon was visible through the slit” (Secrets of Ancient

Navigators). It consisted of a graduated staff, a half-cross in the shape of an arc

of a circle on the radius of the staff with a fixed vane, and a brass horizon vane

with a slit in it at the fore-end of the staff. The device enabled the observer to see

both the sun and horizon without facing the sun.

Photo Credit: http://odock.blogspot.com/2011/02/history-

of-navigation-in-verse.html

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Sextant

The sextant is an invention that

measures the angle between any two

visible objects. It also allowed the user

to determine their latitude to within a sea

mile or two, even from a swaying deck.

The angle, and the time when it was

measured, was used to calculate a

position line on a nautical or aeronautical chart. Other uses of the sextant include

sighting the sun at solar noon and sighting Polaris at night to find one's latitude.

“Sailors could employ the sextant to figure longitude using the lunar-distance

method, but with the astronomical tables of the 18th century, the process could

take several hours to work out one's position” (Secrets of Ancient Navigators).

The Lunar Distance Method

The lunar distance method was

created so navigators could determine

their longitude. In the 1750s, German

astronomer Tobias Mayer developed

the method. For centuries the sextant

allowed individuals to determine their

latitude, however longitude remained

an important missing element. According to The History of the Sextant, the lunar

1

This diagram shows the angles and distances measured in the lunar method.

Photo Credit: http://www.nma.gov.au

2

Photo Credit: http://www.marineinsight.com/misc/marine

-navigation

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distance method allowed the navigator at sea to measure the angle between the

moon and a celestial body, calculate the time at which the moon and the celestial

body would be precisely at that angular distance, and then compare the ship’s

chronometer to the time back at the national observatory.” The chronometer

provided sailors with the accurate time while aboard ships. Once the navigator

knew the correct time from the chronometer, they could then determine the

longitude.

Conclusion

There are numerous ways to navigate using the stars and the sun. It was

through natural navigation that several inventions came about to help individuals

find their way. By locating Plough (the Big Dipper), and Polaris (the North Star),

Cassiopeia, Orion, and Mintaka, one would be able to navigate using stars. Also,

the sun may be used; however, the tilt of the Earth must be considered, as well

as precise time measurements. Over time, inventors, explorers and scientists

invented tools such as: the gnomon, the Arabian Kamal, the astrolabe, the cross-

staff, the back-staff, and the sextant to determine ones latitude. Next time you’re lost and need help navigating, you can consider the

techniques once used by human beings. Before the time of smart phones and

GPS navigators, relied on the stars, Plough, Polaris, Cassiopeia, Orion, and

Mintaka, sun, and inventions such as: the gnomon, the Arabian Kamal, the

astrolabe, the cross-staff, the back-staff, the sextant, and the lunar distance

   Natural  Navigation  

     

method. Incase your batteries were to die on your cell phone; you know how to

natural navigate.

Bibliography

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ion/the_lunar_distance_method

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NAVIGATION", 2010. Web. 16 Feb. 2013.

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