Navigating by the stars
Updates: March 2000
|Daily Updates: May 2000
Latitude: 3 deg 28N
Longitude: 102 deg 16W
Wind Direction: S
Wind Speed: 6 Knots
Sea State: 1
Swell(s) Height: 4-6 Foot
Sea Temperature: 84.2°F (28°C)
Barometric Pressure: 1010 MB
Visibility: 10-25 Nautical Miles
French toast puffs
Creamed beef on toast
Bacon and sausage
Eggs to order and hot cereal
Pineapple and mangoes
Tuna salad sandwich
Split pea soup
Vegetables and chips
Hot potato salad
Fresh bread and vegetables
Shrimp pasta salad
Green tossed salad
Brownies and watermelon
here to watch a video of the launch of DSL-120.
April 10, 2000
By Capt. Eric Buck
ever thought about how you get from one place to another on land? I
don't mean whether you walk, ride a bicycle, or ride in a car, but how
you find your way from where you start to where you are going. On land,
we have trails, paths, roads, signs, and other physical landmarks to
help us navigate from point A to point B. On the ocean, once we get
far enough out to sea, we lose all sight of land and its familiar landmarks.
The ocean is trackless; it offers no obvious markers to guide us. Looking
in one direction, the ocean is just as flat and uniform as looking in
any other direction. How do we know what direction to go?
Now another question: have you ever gazed up at the stars
on a clear dark night? It is amazing how captivating it can be. Perhaps
you wondered how many stars there are, and how far away they are. You will
also have noticed that some stars are brighter than others, and that some
groups of stars form obvious shapes in the sky. Are there any practical
uses for these stars other than filling our minds with a sense of wonderment?
As it turns out, humans have been gazing at the stars and
other celestial bodies for thousands of years and recording information
about how they move. Early on, seafarers used the stars as guideposts to
steer by. As the motions of the stars gradually came to be understood, the
art of celestial navigation was developed so that accurate positions could
be determined at sea. In the last two centuries, marine navigation has progressed
from art to science. Electronics and satellites have revolutionized navigation,
and today we can instantly determine our position with incredible accuracy.
It will be interesting to see what advances this new century will bring
to the science.
Despite all the electronic gadgets, one of the most satisfying
activities for todays navigators is to do things the old fashioned
way; that is, to complete an ocean crossing navigating solely by the stars.
On those clear, dark nights, the stars youve seen that are brighter
than the rest are part of a select group of stars known as the Navigational
Stars. The brightest stars are chosen for navigation because they are the
easiest to identify and are easier to see in the twilight when most celestial
observations are made. The sun, moon and planets can also be used for celestial
navigation. The navigator finds his or her position by using a sextant to
measure the altitudes (heights) of several stars above the horizon. These
readings are compared to predicted altitudes and a line of position is plotted
for each star. The intersection of the lines of position reveals your location.
Many a seasoned navigator can get a rough idea of their whereabouts
just by looking up and seeing what stars and constellations are visible
and where they are in relation to the horizon. When Melville left
San Diego in February, the Big Dipper, perhaps the best-known constellation
in the northern hemisphere, was high in the sky. As we have worked our way
southward, the Dipper is lower and lower in the northern sky. Our arrival
in the tropics was confirmed by seeing the Southern Cross in the southern
sky. How many constellations can you identify? Did you know that quite a
few constellations have several navigational stars in them?
If youre interested in learning more about stars and
constellations, check your library or local bookstore for H.A. Reys The
Stars, A New Way to See Them. If you want more in-depth information,
check out the American Practical Navigator by Nathaniel Bowditch,
the book considered by many to be the bible of navigation. There is also
a wealth of information on star-gazing and using stars and planets for navigation
on the web. A visit to a planetarium or an observatory is another great
way to learn about the stars. . Good star gazing!