Gpc
gigaparsec
Lengthexact by definition
A gigaparsec is one billion parsecs, about 3.086 × 10²⁵ metres or 3.26 billion light-years. It is the scale of observational cosmology: the observable universe has a comoving radius near 14 Gpc, and the largest surveyed structures span a few hundred megaparsecs.
Watch out: At these distances "distance" stops being one quantity. Comoving distance, luminosity distance, angular diameter distance and light-travel distance all differ substantially in an expanding universe, and a figure in Gpc means nothing until it says which one it is.
| 1 Gpc | 3.0856776e+25 m |
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