Saturday, December 13, 2008

How Big is the Universe?

One megalight-year, abbreviated "Mly", is one million light-years, or about 306,600 parsecs. Megalight-years are typically used to measure distances between neighboring galaxies and galaxy clusters.

One gigalight-year, abbreviation "Gly", is one billion light-years — one of the largest distance measures used. One gigalight-year is about 306.6 million parsecs. Gigalight-years are typically used to measure distances to supergalactic structures, including quasars and the Great Wall.

NVDL: Crazy big!
clipped from
The most distant space probe, Voyager 1, was about 14 light-hours away from Earth in the week ending March 9, as of 2007[update]. It took that space probe 30 years to cover that distance.[15]
The Oort cloud is approximately two light-years in diameter. Its inner boundary is speculated to be at 50,000 AU, with its outer edge at 100,000 AU
The nearest known star (other than the Sun), Proxima Centauri, is about 4.22 light-years away.[16][17]
The Milky Way is about 100,000 light-years across.
The Andromeda Galaxy is approximately 2.5 megalight-years away.
The Triangulum Galaxy (M33), at 3.14 megalight-years away, is the most distant object visible to the naked eye.
The nearest large galaxy cluster, the Virgo Cluster, is about 59 megalight-years away.
The Great Attractor lies at a distance of somewhere between 150 and 250 megalight-years (the latter being the most recent estimate).
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