Star count: 70,000,000,000,000,000,000,000
By Allison M. Heinrichs
Los Angeles Times
LOS ANGELES — Imagine all the stars littering the dark sky on a clear moonless night, miles from the glowing city — and then multiply that number by more than 1 million million million. You would come fairly close to the total number of stars that can be viewed by the world's most powerful telescopes, according to a new astronomical survey.
There are approximately 70 sextillion — that's 7 followed by 22 zeros — stars in the known universe, a team led by Australian astronomer Simon Driver announced last week at the 25th General Assembly of the International Astronomical Union in Sydney, Australia.
That means there are more stars in the sky than there are grains of sand in every beach and desert on Earth.
Astronomers made the calculation with observations from the Isaac Newton Telescope in Spain and the Anglo-Australian Telescope in New South Wales as part of a project known as the Two-Degree Field Galaxy Redshift Survey.
First, they determined the density of galaxies in a strip about 1,000th the size of the entire night sky and then figured out about how many stars are in each galaxy. Using the results, they estimated the number of stars in the galaxies visible to the two telescopes.
The astronomers did not originally set out to count the stars; it simply was an interesting side result of more serious research.
"Finding the number of stars is not really the research we were doing," said Nicholas Cross, a Johns Hopkins astronomer and co-author. "But it was a nice result to play around with."
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