Look up at the night sky. The stars first appear white, however, a closer look reveals many different colors. The night sky is filled with glittering jewels. Except for green. Here’s why …
The Colors of Stars
Some stars clearly look yellow, white, orange, or blue. Binoculars gloriously bring out these pastel hues. A small telescope reveals red and even purple. Blacks and browns are out there, too.
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But no green! That’s ironic, because green is the color to which our eyes are most sensitive.
The Sagittarius Star Cloud. Note: In real life, to the eye, reds are rarely as deep as seen here. Blue, yellow, and orange are more common. Credit: NASA
For a quick demonstration of our emerald-tinted vision, look around when twilight deepens. As your vision slowly adjusts, all hues fade out until the last to vanish is … green. By the full Moon, your lawn will still look dimly green when garden roses and violets have all become gray.
This human sensitivity to green is why, in the 1950s, they decided to use that color for the signs in the Interstate Highway System. It also explains why more and more municipalities are replacing their traditional red fire trucks with pale green ones. (Despite this, surveys show that blue is most often named when people are asked their favorite color.)
Why no green stars? Our star (the Sun) and most stars actually do give off green light but also the stars give off enough blue and red light that our eyes end up perceiving many colors at once, so we see it as white. In other words, when such mixtures are involved, so far as our vision goes, the sensation of white is what we see instead of green.
The Colors of Other Celestial Objects
When it comes to the solar system, many planets have no obvious tint. With Venus, Saturn, and Jupiter it’s a case of the bland leading the bland. They seem whitish to the naked eye.
But a few planets do boast decisive color: Neptune looks blue, Mars orange, and Uranus—that’s the cosmic Erin. Its green is obvious through any telescope.
Uranus gets its blue-green color from methane gas in the atmosphere. Credit: NASA
Brilliant meteors, too, sometimes display a vivid green that can appear as in-your-face as a traffic light.
And bright auroras, if you’re lucky enough to see one. Green is far and away the most common color of the Northern Lights.
Just not stars.
.jpg "Northern Lights are Green")
Credit: Anjali Bermain from the Northern Lights Tour With The Old Farmer’s Almanac!
Bob Berman
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St. Charles Co. Parks has an astronomy observing area open 24/7/365 at Broemmelsiek Park 4 Miles ENE New Melle MO 38.72N 90.82W. DD to Schwede, park entrance nearest Schwede&Wilson. Friday nights, weather permitting, Astronomical Society of Eastern Missouri holds open houses where members bring telescopes and share with the public beginning at dark and usually over by 22:00:0. On a clear night with no moon the Milky Way is visible from this site. People are welcome to bring their own telescopes and may get advice on their profitable use from experienced observers some of whom are professional educators in this area-of-interest. The area is always open to anyone for astronomy use any night. Cement pads are provided and have eletric services on cement piers for accessories such as dew heaters or stationary power supplies for scopes with clock drives or GoTo type mounts.
Green is my favorite color and I try to surround myself with it...Oddly, I have always thought Venus looked green to me. I used to live in Alaska and green was definitely the most commom color of the aurora; however, I must admit I most enjoyed the reds purples and blues :).
do you know of anyone near Bryan, Ohio that would be willing to come to my house and show me how to set up my Telescope my Son gave me for Christmas? I am truly sincere in my request and would be so very grateful for any help that could be given. Thank You
What model telescope is it?
In the 1950's most of the school rooms were painted greens, supposedly to help the children learn and keep them focused and calm. Look at the difference between the kids then and now. Maybe they had something.
Hi Mrs. Hodges,
That's because you didn't include me in the study. I went to elementary school in the 50s, and I doubt my parents would have ever held me up as an example of focused and calm. Still, a fascinating topic -- how colors affect us.
Very interesting! I didn't know that. Of course, we could all wear emerald glasses like in Oz.
I read that Zubeneschamali is the only green star but some people disagree. What do you think?
Chris, your letter triggers such wonderful memories for me! As a teenager, I remembering reading a book listing a few stars (like the one in Libra you mentioned) as being green. I felt like a failure that they merely looked white to me. Turns out, they ARE white and those old authors were soon discredited. Best guess is that some observers first looked at a nearby reddish star (like Antares)and when they then quickly turned to observe a white one, their eyes projected the after-image, which is the complementary color!
Great article Bob! I think some people perceive some stars as green. Sometimes I've heard the visual double Albireo described as a yellow-green double. Albireo beta is spectroscopic blue, but nearness to the its visual double causes some people (even occasionally myself) to see it as green.
