A wave breaks when the water that supports a wave is only about 1.3 times as deep as the wave is high.
At that point, the water at the crest is moving faster than the water below.
This condition commonly occurs in shallow water at the shore, but it may occur farther off if the wave is high enough.
Chinese astronomers made the first recorded observation of Halley’s comet in 240 B.C. In 1705, English astronomer Edmund Halley was the first to theorize that comets travel in regular orbits around the sun. Proposing that “the great comet” observed in 1682 made periodic visits about every 76 years, he predicted that it would return in…
A poll of 3,000 Americans yielded the following top five fears: 1. Speaking before a group. 41 percent 2. Heights. 32 percent 3. Insects and bugs. 22 percent 4. Financial problems. 22 percent 5. Deep water. 22 percent
Most of the world’s non-Muslim countries use the Gregorian calendar, introduced by Pope Gregory XIII in 1582 as a reform of the Julian calendar. The latter, instituted by Julius Caesar, had been in use since 46 B.C. Americans have used the Gregorian calendar since 1752. What’s the difference between the the Julian or the Gregorian…
The first to approximate the speed of light roughly was French physicist Armand Fizeau (1819-1896). In 1849 Fizeau obtained a value for the speed of light that was about 5 percent too high. Fizeau’s contemporary Jean Foucault (1819-1868) obtained the first accurate measurement (within 1 percent of the correct speed) in 1862.
At the Pacific Ocean’s greatest depth-36,198 feet (in the Marianas trench southwest of Guam), the pressure is 16,124 pounds per square inch, more than 1,000 times the atmospheric pressure at sea level (14.7 pounds per square inch).
The oldest moon material brought back to earth by the Apollo program crews has been soil-dated to 4.72 billion years.