This makes it the best candidate yet for supporting life.The new planet orbits a star, called Gliese 581, that lies a mere 20 light years away in the constellation Libra.
Not long after the silver denarius, patterned after the Greek drachma, was introduced about 212 bc, the prior copper coinage (aes, or libra) began to be debased until, by the onset of the empire, its weight had been reduced from 1 pound (about 450 grams) to half an ounce (about 15 grams).
Six of these denarii, or "pennyweights," were reckoned to the ounce (uncia) of 423 grains (27.41 grams), and 72 of them made the new pound (libra) of 12 ounces, or 5,076 grains (328.9 grams).
The libra is one of the nonmetric units of weight still used in Spain, Portugal, and several Spanish-speaking countries of the Americas.
One-twelfth of the libra, the Roman uncia, is the ancestor of the English ounce.
In medieval Latin documents the words libra, solidus, and denarius were used to denote the pound, shilling, and penny, which gave rise to the use of the symbols £, s., and d.
Similarly, the first Roman issues, aes grave (heavy bronze), were ponderous cast pieces, the heaviest actually corresponding in weight to the libra, the Roman pound.
The lira was introduced in Europe by Charlemagne (c. 742 814), who based it on the pound (Latin: libra) of silver.
The abbreviation lb for pound is derived from libra.
For just as "lb" came from libra, so the word "pound" is descended from pondo, making the # a descendent of the Roman term libra pondo in both name and appearance.
He is in fact, one of the few etymologists around who are likely to point out that "calibre" stems from the Latin "qua libra" and, in the next breath, to contend that a a parapet is a pet parrot.
