Sirius

Interview on the RAINBOW star from earthsky.org

And Paula wrote, This morning two of us got up early. We found a pulsing star straight down the sky below Orion’s Belt. It was pulsing the colors of green, yellow, blue and red like a strobe light. I will search for it every morning as it was so enchanting.

It is enchanting, so much so that – every year, beginning in the fall – we get many, many questions about a multicolored star twinkling in the southeastern to southern sky after midnight. This star is Sirius in the constellation Canis Major the Greater Dog. It’s sometimes called the Dog Star. Sirius is now rising in the southeast in the hours after midnight now and can be found in the south at dawn. Notice that a line from Orion’s Belt to points to Sirius.

Sirius appears to flash different colors when it’s low in the sky . . . really, all the stars are flashing different colors. That’s because light is composed of all the colors of a rainbow, and the journey through our atmosphere breaks starlight into its component colors.