The yard-arm of a sailing ship –Ī tapered spar used to support a square sail – harkens back to theĮarlier meaning. This changed to gierd in old English and eventually to yard. Or stick, which could be used for measurement. The name originates with the old German word gazdaz for a staff The yard is a unit of distance equal to 3 feet (36 inches) or 0.9144 meters. It's the ship that made the Kessel Run in less than twelve parsecs."
For example, in the Star Wars movie Episode IV: A New Hope, Han Solo says to Obi-Wan: "You've never heard of the Millennium Falcon?. It is a popular misconception that light-year and parsec are units of time.
The parsec is generally used by astronomers in preference to the light-year.įor larger distances, the kiloparsec (kpc) = 1,000 pc or megaparsec (Mpc) The name is a contraction of "parallax-second."ġ parsec = 3.259 light-years = 206,265 astronomical units ( AU) = 30.83 trillion km = 19.16 trillion miles. Which the radius of Earth's orbit subtends an angle of one arcsecond (Fig 1). The parsec (pc) is an astronomical unit of length, equal to the distance at To be a distance equal to one minute of arc (1/60 of a degree) distanceĪlong a great circle and is equal to 6,076 feet. With each foot) of the Roman army were supposed to be two steps, each 2.5įeet long, one thousand paces is very close to the length now called a statute The mile is a measure of distance, the name of which is an abbreviation of the Latin mille passuum or 'one thousand paces.' Since the paces (one step The energy levels 2p 10 and 5d 5 of the krypton-86 atom
Times the wavelength of radiation corresponding to the transition between Fromġ960 to 1983, the meter was defined as the length equal to 1,650,763.73 Got their sums wrong and for 162 years (to 1960), the meter was definedĪs an arbitrary distance between two marks on a bar of platinum kept in Paris – the so-called "international prototype metre". To the equator on the meridian passing through Paris. Spelling) represent one ten millionth of the distance from the North Pole
It was originally intended that the meter ('meter' in European It used, for example, in the measurement of intermolecular distances and wavelengths.Ī sheet of paper is about 100,000 nanometers thick. Alternatively, 1 mile = 1.609 km.Ī micron is a unit of length in the CGS system, equal It is defined by the Internationalīureau of Weights and Measures as the distance traveled by light in a vacuumĪ kilometer (1 km) = 1,000 m = 0.62 mile. The meter (m) is the base unit of length in the SI
A unit generally preferred by professional astronomers The nearest star, ProximaĬentauri, lies at a distance of 4.28 light-years or just over 40 trillion Per second), in one year – about 9.406 trillion kilometers (5.88 trillion miles Since 1959 it has been defined exactly equal to 25.4 millimeters.Ī light-year (ly) is the distance traveled by light, moving at 300,000 kilometers per second (186,282 miles Of a furrow on a square field of 10 acres inĪn inch is a unit of length in the US customary and The word derives from a 'furrowlong' it represented the standard length
There are 12 inches to 1 foot.Ī furlong is an Imperial unit of measurement, equal to 220 yards (about 210 meters). The foot is an old Imperial and US Customary unit of length equal to one-third of a yard or 0.3048 meter. The fermi is a unit of length equal to 10 –13 cm. The Romans used a cubit equal to 17.4 modern inches To the length of a person's forearm, i.e., the part of the arm from theĮlbow to the fingers. light-year equals 63,240 AU.Ī cubit is a measure of length used in the ancient world. One angstrom is equal to 0.1 nm (nanometers), or 10 –10 m.Īn astronomical unit (AU) is the mean distance between Earth and the Sun. It is named after the Swedish physicist Anders Ångström. The angstrom (Å) is the CGS unit used to express