Convert Petameter to Meter

A petameter is a metric unit of length equal to one quadrillion meters (1×10¹⁵ m). It is rarely used in everyday or scientific contexts; astronomers prefer the light-year or parsec for these scales.

The petameter uses the SI prefix peta- (from Greek penta, five, by analogy with the exponent's relation to thousand-cubed-cubed), adopted by the CGPM in 1975 to denote 10¹⁵.

Petameters could express interstellar-scale distances but are almost never used in practice. A light-year is approximately 9.46 Pm; astronomy uses light-years and parsecs as standard.

SI prefix peta- adopted in 1975; the petameter is rarely used because astronomy has well-established non-SI units (light-year, parsec) for this scale.

The meter is the SI base unit of length. Since 2019, the meter has been defined by fixing the numerical value of the speed of light in vacuum to exactly 299,792,458 meters per second. Every other SI length unit derives from the meter.

The meter was originally defined in 1793 by the French Academy of Sciences as one ten-millionth of the distance from the equator to the North Pole along a meridian through Paris. It has been redefined multiple times — by physical prototype, then by atomic transitions, and finally in 2019 by fundamental physical constants.

The meter is the international standard for length in science, engineering, construction, athletics, and everyday measurement in metric countries. It underpins definitions of area (m²), volume (m³), and most derived SI units.

Established 1793 in France; ratified internationally via the Metre Convention 1875; redefined in 1960, 1983, and most recently 2019 when the SI redefinition fixed it to the speed of light.