When a plane travels faster than the speed of sound, it creates this thunderous noise
An empty Goodyear blimp weighs over 12,000 lbs.; when they fill it with this gas, it weighs only 100 to 200 pounds
The Celsius temperature scale is also called this, meaning "divided into one hundred parts"
On Oct. 15, 2003 it became the third country to launch a man into space; the Shenzhou 5 spacecraft orbited the Earth 14 times
In 1901 Eugene Demarcay discovered Eu, this rare-earth metal that's named for a continent
If an atom loses one of these, it becomes a cation, a positively charged ion
(Cheryl of the Clue Crew at the Eli Whitney Museum in New Haven, Connecticut) In the 1940s, Dr. William Sewell created an artificial one of these, using parts from an erector set
The tokamak, this type of nuclear reactor, uses plasma heated to 180 million degrees as fuel
This computer device slowly takes you online
In 1859 Robert Fouls invented a steam-powered one of these to singal imperiled ships