This picture looks like just another shot of the edge of the planet, doesn’t it? You can see the layering of the atmosphere, which is cool, but it’s otherwise unremarkable. But wait! What’s that weird double blip above the horizon?
That’s Alpha Centauri, the nearest star system to the Sun!
How freaking cool is that? Cassini was about 530,000 km (330,000 miles) from Saturn when it took this shot, but those two stars were 80 million times farther away!
That picture is no accident. One thing scientists like to do is watch bright stars go behind the planet Saturn itself. As the planet’s atmosphere dims and eventually blocks the star’s light, astronomers can determine all sorts of things about Saturn’s air: its composition, distribution and density with height, and much more… so they tracked the famous duo as they passed behind the planet itself.
http://blogs.discovermagazine.com/badastronomy/2010/08/05/saturn-and-the-nearest-star/