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Loading contentThe region of the Universe from which light has had time to reach us since the Big Bang.
Because light travels at a finite speed and the Universe has a finite age, we can only see out to a certain distance. Owing to expansion, the edge of the observable Universe now lies about 46 billion light-years away, giving a sphere roughly 93 billion light-years across — a tiny, and possibly infinitesimal, part of the whole.
| Diameter | ≈ 93 billion light-years | NASA |
Facts on this topic will be cited from these primary and reference sources.
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.