megaparsec

noun

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Forget about writing a tower of powers that stretches out for miles or megaparsecs. Ben Brubaker, Quanta Magazine, 22 Aug. 2025 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 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 Previous measurements of universal expansion were split between either 67 or 72 kilometers per second per megaparsec. Nathaniel Scharping, Discover Magazine, 16 Oct. 2017

Word History

Etymology

mega- + parsec

First Known Use

1920, in the meaning defined above

Time Traveler
The first known use of megaparsec was in 1920

Browse Nearby Words

Cite this Entry

“Megaparsec.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/megaparsec. Accessed 9 Sep. 2025.

More from Merriam-Webster on megaparsec

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!