Convert Terameter to Meter

A terameter is a metric unit of length equal to one trillion meters (1×10¹² m). It is rare in everyday use but appears in astronomy when expressing solar-system-scale distances in SI units.

The terameter uses the SI prefix tera- (from Greek teras, monster), adopted by the CGPM in 1960 to denote multiplication by one trillion (10¹²).

Terameters are occasionally used in astronomy to express distances on the order of Earth–Sun (~0.15 Tm or 1 AU) and outer-planet distances. The astronomical unit (AU) and light-hour are more common in practice.

SI prefix tera- adopted in 1960; the terameter is the standard SI prefix unit for distances comparable to inter-planetary scales but is less common than the AU in working astronomy.

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.