:
navigation by observation of the positions of celestial bodies
.
Celestial navigation continues to be used by private yachtsmen, and particularly by long-distance cruising yachts around the world. Celestial navigation uses
sights, or angular measurements taken between a celestial body (the sun, the moon, a planet or a star) and the visible horizon
.
:
navigation by observation of the positions of celestial bodies
.
Celestial navigation accomplishes its purpose by
use of angular measurements (sights) between celestial bodies and the visible horizon to locate one’s position on the world
, whether on land, in the air or at sea.
For sailors, celestial navigation is a step up from dead reckoning. This technique uses
the stars, moon, sun, and horizon to calculate position
. It is very useful on the open ocean, where there are no landmarks. … They also need an accurate clock and an almanac giving the positions of celestial bodies.
The theoretical accuracy of celestial position fix is
within 0.1 mile of your true position
. In comparison, a modern GPS should be able to give you an accuracy of less than 1 meter. … While the theoretical maximum accuracy of a celestial fix is 0.1 miles, in reality you will probably never achieve closer than 1 mile.
Three main types of navigation are
celestial, GPS, and map and compass
.
compass
, in navigation or surveying, the primary device for direction-finding on the surface of the Earth. Compasses may operate on magnetic or gyroscopic principles or by determining the direction of the Sun or a star.
Is a sextant still used today?
It’s a real historic instrument that is still in use today
. Even today big ships are all required to carry working sextants and the navigating officers have regular routines to keep themselves familiar with making it work.
Under optimal conditions, approximately 6,000 stars are visible to the naked eye of an observer on Earth. Of these,
58 stars
are known in the field of navigational astronomy as “selected stars”, including 19 stars of the first magnitude, 38 stars of the second magnitude, and Polaris.
Once you have taken your sights, you compare the measured altitude to an altitude you calculate from the nautical almanac. The difference between the two gives you an intercept for each star.
Once you have at least three intercepts, spread around 60° apart
, you can plot them and get a celestial position fix.
You just need your eyes and a dark sky and a little guidance. The most important, and easiest star to find in the night sky is the North Star, or
Polaris
(also called the Pole Star). The North Star is located at the tip of the handle in the constellation, the Little Dipper.
Why is the inertial navigation system combined with celestial navigation system? … Explanation:
Navigational systems use Kalman filtering techniques to integrate all the sensed navigational data to obtain the best estimate navigation solution.
Topics include:
selecting stars for navigation
, use of a sextant, use of correction factors (e.g. refraction, dip, instrument error), use of sight reduction tables, and the determination of longitude and latitude using an Earth-based coordinate system.
All it is is a device that measures the angle between two objects. The sextant makes use of two mirrors. With this sextant, one of the mirrors ( mirror A in the diagram) is half-silvered, which allows some light to pass through. In navigating, you look at the horizon through this mirror.
