Galileo's Pendulum

(Every day until Christmas, I’ll be posting a science-related image.)

Day 18

Probably my favorite astronomical image of all time shows Saturn eclipsing the Sun. It’s a view we’ll never see from Earth: Saturn orbits farther out than we do, so it will never pass between us and the Sun. However, the Cassini probe (my favorite spacecraft!) frequently flies beyond Saturn, so its course allows it to see the eclipse. The image above is a second view of this type, and as stunning as my favorite image.

Part of what makes these images so striking is that the rings of Saturn—made of small chunks of ice—reflect a lot of sunlight back onto the night side of the planet. Unlike the earlier eclipse photo, the picture above is a composite, bringing together visible light (in the violet and red filters) with infrared (the parts of the image that appear green). The result is stunning, highlighting many things that we couldn’t see, even if we flew out to the planet.

Some might say this is not a real photo, since the colors in the image aren’t what we would perceive, but I disagree strongly. We use technology as extensions to our senses all the time: eyeglasses, microscopes, magnifying glasses, and telescopes all allow us to see things beyond our ordinary vision. Probes like Cassini take one step farther, bringing greater beauty and understanding of the wonderful Universe we inhabit.