The planet Saturn glows in subtle shades of tan, yellow, and ivory in this image from the Cassini spacecraft. The colors come from sulfur, ammonia, water, and other compounds in the atmosphere. Different chemicals form different bands of clouds, all of which completely encircle the giant planet. Saturn shines at its best in mid-April, when it lines up opposite the Sun in Earth's sky. It rises around sunset, climbs high across the sky during the night, and sets around sunrise. It looks like a bright golden star. [NASA/JPL/SSI]
Most of the colors in the night sky are subtle -- a hint of orange here, a smidgen of blue there. But they become a little more obvious when two objects of contrasting color stand close together.
Now, for example, the planet Saturn and the star Spica stand side by side as night falls, low in the eastern sky. Saturn is the brighter of the two. In fact, it’s at its brightest for the entire year because it lines up opposite the Sun in our sky. It rises around sunset and remains in view all night. It’s closest to Earth for the year, too, which is why it shines brightest.
If you look carefully, you’ll notice not just a difference in brightness between Saturn and Spica, but a difference in color as well.
Saturn has a distinctly golden glow. The giant planet’s atmosphere is topped by bands of clouds that are colored yellow, tan, and white by various chemical compounds. From Saturn’s great distance -- close to 800 million miles right now -- those bands blend together to give the planet an overall yellow-gold appearance.
Spica, on the other hand, shows a subtle hint of blue -- a color that’s enhanced by the star’s proximity to Saturn. Spica’s color comes from its surface temperature -- thousands of degrees hotter than the surface of the Sun. Hot stars shine blue or white while cool stars shine orange -- just part of the subtle palette of color in the night sky.
Script by Damond Benningfield, Copyright 2012
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