Our eyes see color through cones in our retina, where the three different types (S, M, and L) each have a slightly different range of wavelengths to which they are light sensitive. Through the response of these different cones our brains are able to distinguish different wavelengths of light, which we interpret as color. Telescope detectors typically have a much wider range of light sensitivity, which is good if you want to detect a great deal of light, but not so good if you want to observe a particular color range. So many telescopes have filters that block light outside a particular range.
Fiat Lux
In 1671, Isaac Newton submitted a letter to the the Royal Society outlining a new theory of light and color. While Newton is probably most famous for his theory of gravity—and the mythical apple—he was also deeply interested in the nature of light, and made one of the first detailed studies of the properties of light. The work he describes in this 1671 paper is so brilliantly simple you can do it at home. All you need is some sunlight and a couple of prisms.
Color Scheme
By the 1900s, physicists gave us an understanding of the relationship between the color of light a star gives off and its temperature. The coolest stars (with surface temperatures of about 2 000 K) glow dim red, while higher temperature stars glow orange, yellow, white and blue.
No Irish
It’s St. Patrick’s day, and that means many will celebrate their Irish heritage and wear the green. But stars never wear the green. You will never see a green star.
The Color of Speed
In our everyday lives, we’re familiar with the Doppler effect as it applies to sound. You might notice when a car or train passes you, its sound shifts downward as it passes. This is because the sound waves from an object are bunched together as it moves toward you, and stretched apart as it moves away from you. For light a similar thing occurs.
Rainbow Shadows
The part of the solar atmosphere that produces the light we see is called the photosphere. The solar atmosphere above that is cooler than the photosphere, so it creates an absorption spectra. This is useful because we can use it to identify what atoms or molecules are in the upper atmosphere of the sun, and of course that helps tell us what the sun is made of.
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