What is the geographic center of the United States?

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.

The term noble gas refers to the lack of chemical reactivity in these inert gases. For the record, there are six noble gases: helium, neon, argon, krypton, xenon, and radon.

The call is close. Over the course of 12 hours in Granville, North Dakota, on February 21, 1918, the temperature rose 83 degrees. It went from –33 degrees Fahrenheit in the early morning to 50 degrees near the end of the afternoon. But in Fairfield, Montana, over the course of 12 hours on December 24,…

Astronomers once believed that a planet called Vulcan existed between the planet Mercury and the sun. Its existence, first proposed by French astronomer Urbain Jean Joseph Leverrier in 1845, was hypothesized to explain a discrepancy in Mercury’s orbit. Vulcan was even reported to have been observed once, but the observation was never confirmed. Einstein’s general…

Plastics are only one kind of polymer, a substance composed of very large chain-like molecules that consist of smaller, repeating chemical units. Natural polymers include proteins, cellulose, diamonds, and quartz. Besides plastics, man-made ones include concrete, glass, and paper.

The Consumer Product Safety Commission reports that the five most dangerous sources are: stairs, glass doors, cutlery, glass bottles and jars, and home power tools.