Jan. 22, 2007 — One of the most distant images of Earth, and probably the most surreal, has been beamed home from the Cassini spacecraft.
In the unique shot from the orbit of Saturn, Earth appears as a tiny bright dot shining through the gas giant's rings. If not for the fact that Earth is actually about 900 million miles away, it looks a lot like one of Saturn's moons.
Such an image of Earth is only possible when Cassini is deep in Saturn's shadow, with the Sun blocked from view, explain researchers on the Cassini science team.
"It's an eclipse of the Sun by Saturn," explained Cassini imaging team member Matt Hedman of Cornell University. That's important because Earth always appears close to the Sun from the perspective of Saturn, which makes it impossible to see with Cassini's imager without the glare of the Sun damaging the equipment. "You can't even have the Sun close to the image."
What's more, because of its orbital path, Cassini isn't often in Saturn's shadow, so it's rare to have this view at all, Hedman said. But it's not really Earth that scientists were anxious to see in the new image — which itself is composed of several images.
"The big science reason to take this shot is that we're looking at forward-scattered light," said Hedman, referring to sunlight not reflecting back toward the Sun, but scattered away from the Sun by small particles in Saturn's rings.
These particles are more visible in forward-scattered light, he said, much like the smudges on glasses held up to the light.
