Are some stars different colors than others? Yes, they are! Stars exist in all the colors of the rainbow, from red to violet. Some are actually infrared (redder than red) and some are ultraviolet (more violet than violet). The colors of brighter stars often appear white because they are so bright, and dimmer stars also appear white because they are not bright enough to be seen by the color cones in the retinas of your eyes.

Looking at the constellation Orion’s (the hunter) left shoulder star, Betelgeuse, you may note that it appears a big orange-red. Aldebaran, the eye of Taurus the bull, also appears orange-red. Rigel, Orion’s right knee may appear to be rather blue. All these stars are very high and southward in the evening sky at this time of year.

Star colors tell us the star’s surface temperature. Red stars are cooler and blue stars are hotter. Infrared stars, the coolest, may only be 3000 degrees Kelvin (5000 degrees Fahrenheit). The hottest stars are in the ultraviolet and may be as hot as 40,000 degrees Kelvin (71,500 degrees Fahrenheit). Astronomers accurately measure a star’s color using a spectroscope. Spectra from a star are split into their individual colors and the information is then interpreted by a computer.

Be sure to visit the Insperity Observatory website: humbleisd.net/observatory to see how to sign up for public night on the first Friday each month (COVID-19 and weather permitting). Join in to explore all the colors in the universe. Reservations are required.

Aaron Clevenson
Author: Aaron ClevensonEmail: This email address is being protected from spambots. You need JavaScript enabled to view it.
I am the observatory director at the Insperity Observatory in Humble ISD. I am also an adjunct astronomy professor at Lone Star College-Montgomery where I teach solar system astronomy and stars and galaxies astronomy. I am the author of the astronomy textbook, “Astronomy for Mere Mortals.” I am a past president of the North Houston Astronomy Club, and was the chair of Astronomy Day in Southeast Texas in 2015 and 2016. He is an observing program director with The Astronomical League, coordinates their Master Observer Progression Awards, and has authored six of their observing programs.

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