Gigametre

1 gigametre =

SI units
1.000×10^6 km	1.000×10^9 m
Astronomical units
6.685×10^−3 AU	105.7×10^−9 ly
US customary / Imperial units
621.4×10^3 mi	3.281×10^9 ft

13 objects with sizes in the gigameter order of magnitude

The gigametre (official spelling used by the International Bureau of Weights and Measures;^[1] SI symbol: Gm) or gigameter (American spelling) is a unit of length in the metric system, equal to one billion metres, the SI base unit of length, hence to 1,000,000 km or approximately 621,370 miles.

Gigametres (from the Greek words gigas = giant and metro = count/measure) are rarely seen in practical use. They are too big for any terrestrial lengths, and gigametre distances in astronomy (e.g. a planet's distance from its star) are usually given in astronomical units (AU) or in (millions of) kilometres.

• Earth's average distance from the Sun is 149.6 Gm or 1 AU.
• Jupiter's average distance from the Sun is 778.5 Gm or 5.2 AU.
• Osiris' average distance from the parent star HD 209458 is 6.7 Gm or 0.045 AU.
• PSR J1719-1438 b's average distance from the pulsar PSR J1719-1438 is 0.666 Gm, which is the smallest orbit of any known exoplanets.
• The mean diameter of the Sun is 1.393 Gm.^[2]
• The mean diameter of red supergiant star Betelgeuse is 1,302 Gm.

See also

• 1 E+9 m
• Conversion of units, for comparison with other units of length
• Light year
• Metric system
• Orders of magnitude (length)
• Parsec
• SI
• SI prefix

References

1. "Definition of the metre". BIPM. Retrieved 26 March 2014.
2. Emilio, Marcelo; Kuhn, Jeff R.; Bush, Rock I.; Scholl, Isabelle F. (March 5, 2012), "Measuring the Solar Radius from Space during the 2003 and 2006 Mercury Transits", arXiv, retrieved March 28, 2012