The Reason For Measuring Lunar Distances
In celestial navigation, precise knowledge of the time at Greenwich and the positions of one or more celestial objects are combined with careful observations to calculate latitude and longitude. Reliable marine chronometers were unavailable until the late 18th century and not affordable until the 19th century. For approximately one hundred years (from about 1767 until about 1850) mariners lacking a chronometer used the method of lunar distances to determine Greenwich time, an important step in finding their longitude. A mariner with a chronometer could check and correct its reading using a lunar determination of Greenwich time.
Read more about this topic: Lunar Distance (navigation)
Famous quotes containing the words reason, measuring, lunar and/or distances:
“The real risks for any artist are taken ... in pushing the work to the limits of what is possible, in the attempt to increase the sum of what it is possible to think. Books become good when they go to this edge and risk falling over it—when they endanger the artist by reason of what he has, or has not, artistically dared.”
—Salman Rushdie (b. 1947)
“... there is no way of measuring the damage to a society when a whole texture of humanity is kept from realizing its own power, when the woman architect who might have reinvented our cities sits barely literate in a semilegal sweatshop on the Texas- Mexican border, when women who should be founding colleges must work their entire lives as domestics ...”
—Adrienne Rich (b. 1929)
“A bird half wakened in the lunar noon
Sang halfway through its little inborn tune.”
—Robert Frost (1874–1963)
“We then entered another swamp, at a necessarily slow pace, where the walking was worse than ever, not only on account of the water, but the fallen timber, which often obliterated the indistinct trail entirely. The fallen trees were so numerous, that for long distances the route was through a succession of small yards, where we climbed over fences as high as our heads, down into water often up to our knees, and then over another fence into a second yard, and so on.”
—Henry David Thoreau (1817–1862)