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The Question
(Submitted November 27, 2002)
The Hubble Space Telescope (HST) site estimates there are hundreds of billions
of galaxies in the universe. A recent German super-computer simulation
estimates that the number may be as high as 500 billion! Can someone
please clarify the accepted educated ballpark figure? Thanks a billion!
The Answer
Your inquiry is definitely in the minds of many scientists who are
trying to obtain a good estimate for the number of galaxies in the
universe. The methods used to achieve such number varies, and
therefore, the results would vary, too. Also, as new and improved
technology becomes available, astronomers can detect fainter objects
that were not seen before. These objects that have come into view
will in turn change the estimated number of galaxies.
For example, in 1999 the Hubble Space Telescope estimated that there were
125 billion galaxies in the universe, and recently with the new camera HST
has observed 3,000 visible galaxies, which is twice
as much as they observed before with the old camera. We're emphasizing
"visible" because observations with radio telescopes, infrared
cameras, x-ray cameras, etc. would detect other galaxies that are not
detected by Hubble. As observations keep
on going and astronomers explore more of our universe, the number of
galaxies detected will increase. For more about the Hubble Space Telescope,
check out this web site:
http://www.stsci.edu/hst/
Hope this helps,
Georgia & Veronica
For "Ask an Astrophysicist"
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