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[cdn-nucl-l] "Hubble hoax" debunked
Here's a great little contribution to the fight against journalism's
incompetence in science & technology....
Jaro
^^^^^^^^^^^^^^^^^^^^^
http://www.canada.com/montreal/montrealgazette/letters/story.asp?id=21FB4223
-B26D-4335-BAB3-F9206AB0B947
The Gazette
Friday, September 12, 2003
Your Sept. 9 editorial "Hubble hoax" claimed the Hubble Space Telescope
transmits images in "just grainy black and white" that are subsequently
doctored by "astronomers and marketing wizards" and are, therefore,
"dishonest" representations of nature.
This shows a misunderstanding of basic physics and astronomy, as well as of
the capabilities of the Hubble Space Telescope.
First, it is false to say Hubble's images are really black and white.
Hubble images are usually composites made of images taken with different
colour filters, similar to how conventional colour computer and television
screens represent colour.
It is true an image taken with a single colour filter is represented by an
intensity scale that could also be represented by shades of grey; however,
that intensity scale accurately reflects the intensity of light within a
well-defined, narrow region of the electromagnetic spectrum.
Although it might be true Hubble images are often enhanced to appear
different from what the human eye could see if it had the same
magnification, "false colour" is standard practice in any astronomical
imaging and is not intended to deceive or misinform but rather to highlight
distinct emission regions the eye might not otherwise distinguish.
For example, though the eye would see a beautiful spiral galaxy as
essentially "white," a colour-enhanced image, in which the red image was
made artificially more intense relative to blue, would reveal that same
spiral galaxy actually has different components, with hot young blue stars
dominating the emission in the spiral disk and the cool old red stars
forming a surrounding spherical halo.
Thus, images you call "dishonest" are in fact revealing important truths
about nature true colour images never could.
If all astronomical images were presented as a human eye would see them, the
majority would be completely blank.
We can see only a tiny fraction of the electromagnetic spectrum.
Stars and galaxies produce radiation that ranges from radio waves right up
to gamma rays.
Billions of objects in the universe, including spectacular black-hole
systems, neutron stars and remnants of supernova explosions would be
rendered completely invisible to the public if The Gazette had its way.
As for Hubble images being "grainy," that is a term usually reserved to
describe old-fashioned film, not the charge-coupled-device technology used
by modern telescopes, including Hubble, in which images are recorded
digitally.
There literally is nothing "grainy" about them.
Victoria Kaspi
Canada Research Chair in Observational Astrophysics McGill University