Photographer Amanda Cross, of Lancashire, UK, wrote:
I wanted to compare the colors of different stars next to each other. These are stacks of Rigel, Betelgeuse and Sirius. I took individual images 60 seconds apart with iso 16000 and speed 1/50, stacked them with starstax and presented them together to show the different colors of the stars. I took the images deliberately out of focus to show the colors. The color variations are from the Earth’s atmosphere which splits the light from the star and the camera picks up the colors.
Bottom line: Photo compares colors of stars Rigel, Betelgeuse and Sirius.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.