STAR COLOR VERSUS TEMPERATURE

All stars are very hot! However, some stars are cooler or hotter than others. Star color indicates relative temperature: cooler stars shine with more light in the red-orange-yellow wavelengths of the electromagnetic spectrum; hotter stars shine in the bluish wavelengths of the electromagnetic spectrum.

For example, Arcturus is the bright red-orange star in the constellation Bootes, the Herdsman (Bear Driver). In the real sky, the arc of the Big Dipper's handle points toward Arcturus (remember the mnemonic: "Follow the arc to Arcturus."). Sirius is the blue-white star in the constellation Canis Major, the Big Dog.