mega·​par·​sec ˌme-gə-ˈpär-ˌsek How to pronounce megaparsec (audio)
: a unit of measure for distances in intergalactic space equal to one million parsecs

Examples of megaparsec in a Sentence

Recent Examples on the Web Previous measurements of universal expansion were split between either 67 or 72 kilometers per second per megaparsec. Nathaniel Scharping, Discover Magazine, 16 Oct. 2017 Planck mission scientists arrived at a Hubble constant of 67.5 plus or minus 0.5 kilometers per second per megaparsec. Ashley Strickland, CNN, 23 May 2022 Hubble’s data shows that the universe’s expansion rate is around 73 kilometers per second per megaparsec. Joshua Hawkins, BGR, 20 May 2022 In their analysis, H0 comes out to be 73.04 ± 1.04 kilometers per second per megaparsec. Anil Ananthaswamy, Scientific American, 18 Apr. 2022 Each number is an expression of the same thing—the kilometers-per-second rate of cosmic expansion per every megaparsec (roughly 3.26 million light-years) of space. Daniel Leonard, Scientific American, 25 Jan. 2022 The trend continued; as of their latest analysis last March, Riess’s team pegged the Hubble constant at 74 kilometers per second per megaparsec, 9% higher than the 67.4 extrapolated from the early universe. Quanta Magazine, 26 Feb. 2020 Under certain assumptions about the fundamental nature of the universe, Planck data suggest that the Hubble constant should have a value of 67.4 kilometers a second per megaparsec, give or take 0.5. Michael Greshko, National Geographic, 12 Sep. 2019 The Planck team predicts that the universe should expand at a rate of 67.4 kilometers per second per megaparsec. Quanta Magazine, 8 Aug. 2019

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'megaparsec.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


mega- + parsec

First Known Use

1920, in the meaning defined above

Time Traveler
The first known use of megaparsec was in 1920

Dictionary Entries Near megaparsec

Cite this Entry

“Megaparsec.” Dictionary, Merriam-Webster, Accessed 21 Jul. 2024.

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