Hubble's constant

American  

noun

Astronomy.

1. the ratio of the recessional velocity of galaxies to their distance from the sun, with current measurements of its value ranging from 50 to 100 kilometers per second per megaparsec.

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Etymology

Origin of Hubble's constant

First recorded in 1950–55; after E. P. Hubble

Example Sentences

The universe is still expanding, at a rate of 73 kilometers per second per megaparsec, a metric known as Hubble's constant.

From Salon • Feb. 2, 2023

Hubble’s constant – proposed by Edwin Hubble in the 1920s – reveals by how much.

From The Guardian • May 10, 2018

Astronomers express the value of Hubble’s constant in units that relate to how they measure speed and velocity for galaxies.

From Textbooks • Oct. 13, 2016

Lemaître also used data from others to derive the constant governing the expansion, known today has Hubble's constant.

From Scientific American • Jun. 27, 2011

But Dr. Ira Bowen, director of Mount Wilson and Palomar observatories, prefers to say "several billion" lightyears; he suspects that Hubble's constant may not be accurate over such enormous distances.

From Time Magazine Archive