RitcheyRch
04-02-2007, 07:09 AM
http://www.wired.com/science/discoveries/news/2007/04/dayintech_0402
April 2, 1845: Photographing the Sun, Measuring Speed of Light
Tony Long 04.02.07 | 2:00 AM
1845: French physicists Armand H. L. Fizeau and J. Leon Foucault take the first photograph of the sun.
Photography was in its infancy -- and the widespread use of photography in astronomy was still decades away -- when Fizeau and Foucault turned their camera toward the brightest object in Earth's sky.
A few years later, Fizeau and Foucault were both experimenting with methods to determine the speed of light. Fizeau, bouncing a beam of light off a mirror and through a cogged wheel, determined a speed of 313,000 kilometers per second. Foucault ran essentially the same experiment but used a rotating mirror in place of the wheel. He concluded light traveled at 298,000 kilometers per second.
In 1926, a more precise measurement, taken using a rotating prism, accurately fixed the speed of light at 299,796 kilometers (or 186,285 miles) per second.
April 2, 1845: Photographing the Sun, Measuring Speed of Light
Tony Long 04.02.07 | 2:00 AM
1845: French physicists Armand H. L. Fizeau and J. Leon Foucault take the first photograph of the sun.
Photography was in its infancy -- and the widespread use of photography in astronomy was still decades away -- when Fizeau and Foucault turned their camera toward the brightest object in Earth's sky.
A few years later, Fizeau and Foucault were both experimenting with methods to determine the speed of light. Fizeau, bouncing a beam of light off a mirror and through a cogged wheel, determined a speed of 313,000 kilometers per second. Foucault ran essentially the same experiment but used a rotating mirror in place of the wheel. He concluded light traveled at 298,000 kilometers per second.
In 1926, a more precise measurement, taken using a rotating prism, accurately fixed the speed of light at 299,796 kilometers (or 186,285 miles) per second.