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Students use their sextants to take a Sun shot at local noon.
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"How do these things work?"
That was the question that kept coming up during Steven Branting's creative thinking and pre-
engineering course two years ago. His students wanted to know how
maritime sextants and astrolabes worked.
Which is what led Branting, who teaches at Jenifer Junior High School and Lewiston High School in Idaho, to develop a comprehensive unit around the use of the modern-day marine sextant. With grants from a local company and his school board, Branting created a unit that begins with the history of navigation, and includes material on
how to:
solve problems of grids on curved surfaces calibrate sextants to ensure mirror accuracy determine and take a local noon shot use an ephemeris to find "equation of time" and "declination" for any given date calculate latitude and longitude from a local noon sighting use an artificial horizon
NOVA's "Lost at Sea: The Search for Longitude," which premiered Fall 1998, was a natural tie-in. Branting uses clips from the program to help students understand the role timekeeping plays in navigation and the need for accurate timepieces.
The materials for Branting's unit include a student handout, classroom transparency set, student and teacher sextants, Internet access (to connect to the U.S. Naval Observatory clock) and a copy of the NOVA video.
Branting, a facilitator of gifted education, has developed several additional uses of the sextant as a teaching tool in mathematics and geology. A sextant
can be used:
As a pelorus, an instrument meant
to determine a ship's bearing in
relation to a distant object. Turning
the sextant to a horizontal position,
this capability can be adapted to
calculate the distance to an object
using the trigonometric tangent
function. to calculate the distance to tree
leaves that have created images of
the Sun on the ground. to measure the angle of repose for
talus slopes (the slopes of rock at
the base of a cliff) in basalt
formations.
Branting's unit can be found on
NOVA Online.
—Karen Hartley
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