Top: Science: Astronomy: Terminology: J




[ history ]

Jet Propulsion Lab

An outgrowth of the Guggenheim Aeronautical Laboratory of Caltech, in Pasadena (near Los Angeles, California). JPL was the center of US rocket development in World War II and was founded by Theodore Von Karman and Frank Malina. Today it is the focus of NASA's exploration of the planets and of distant space.


[ history ]

Jewish Calendar

The calendar traditionally used to determine Jewish holidays. It is a Metonic calendar based on the motions of both Sun and Moon.


[ history ]

Joule

Unit of energy: the ability to overcome one Newton along 1 meter (assuming g = 10 meter/sec2, it is also the energy required to lift 1 kg by 0.1 meters). Named for James Prescott Joule, one of the first to measure the "rate of exchange" between mechanical energy and heat.


[ history ]

Julian Calendar

Introduced in 46 BC by the Roman ruler Julius Ceasar, this calendar assumes a year of 365.25 days, and uses a cycle in which 3 "ordinary" years of 365 days are followed by a "leap year" with 366 days. Leap years are the years whose number is divisible by 4.



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