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Question
hi what colour are stars? and what can change colour and shape?
Hi Liam,
Stars come in all colors....from deep blue to deep red, with every
color inbetween. EVERY star has it's main, prominent color. It is all dependent on their "surface temperature" which is really the temperature of their uppermost photosphere layer.
The reds are cool stars, like 6000 degrees F,
Yellow stars like the sun are 11,000 degrees F,
and blue white stars are the hottest normal stars at about 50,000
degrees F.
The change in color and and shape (that you see with the naked-eye
in the night sky) is all atmospherics and high thin clouds. If
we didn't have an atmosphere, no star would twinkle, change color
or shape, plus no rainbows, red sunsets, Harvest yellow-orange moons,
no haloes, no sundogs, no circumzenithal arcs....in effect, anything
you see that is not normal in the sky is all caused by our atmosphere. With no atmosphere, we would not even see meteors
(shooting stars) either. Our sky would be the same as the lunar
sky with no changes at all in either color or brightness.
Oh, with naked-eye we only see a slight color in just the brighter
stars. The dimmer stars, we don't see color because the rods in
our retina (our usual night vision) do not contain color receptors, so all the dim stars just appear white. You need lots of light to see color, because daylight vision we use the cones in the retina, and that's where all the color receptors are located, not in the rods of the retina.
Hope all this helps,
Clear Skies,
Tom Whiting
Erie, PA USA
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Answers by Expert:
Tom Whiting
Expertise
Astronomy has been my hobby/pasttime for over 50 years. Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions. No astrology questions please, or questions about alleged UFO picture identifications.
Experience
Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at:http://www.velocity.net/~bwhiting and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.
Organizations: President, Erie County Mobile Observers Group for over 15 years.
Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).
Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions; Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).
Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.
Education/Credentials
BS Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA
Also retired USAF pilot, 20 years.
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