In Saturn’s Shadow

One of the most astounding images of the space age is about to be replicated. Take a look at this image of a backlit Saturn eclipsing the sun. This is a mosaic of images taken over three hours in September, 2006, adjusted to resemble natural color as closely as possible, taken by the Cassini spacecraft currently in orbit around Saturn.

Backlit Saturn

But this picture has been resized to fit on a typical computer screen. Here is the link for a full-resolution image. The night side of Saturn is illuminated by reflected light from the rings. The rings are backlit; the sunlight is being scattered through the ring particles. Outside the bright main rings that circle nearer the planet, you can see the diffuse, dim and narrowly confined G ring. The broader E ring encircles the whole system. The small moon Enceladus, whose icy eruptions are the source of the particles in the E ring, can be seen embedded in the ring at its far left edge. And over 700 million miles away, on the left between the G ring and the brighter main rings from this perspective, is a pale blue dot that is our home planet Earth.

An image such as this could only exist in our imagination before the era of interplanetary space missions—and it’s about to happen again.


On July 19, Cassini will once again fly into Saturn’s shadow and aim its cameras back at the planet. Over four hours, a full end-to-end mosaic of images of the ring system will be acquired. Some of those images (taken through different filters so as to create a color image) will once again include a barely one pixel wide image of the Earth. Those images will be taken between 5:27 and 5:42 p.m. EDT. (Light travel time is already accounted for here.) So go outside and wave! Your picture is being taken from hundreds of millions of miles away.

Here is an image of the portion of the Earth’s surface that will be visible at that time; North America is in the illuminated portion at the top.

Illuminated Earth

And here is one showing the expected positions of Saturn and Earth.

Saturn

Smile for your portrait, Earth!

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Posted in Planets, Solar System, Spacecraft

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Neal Sumerlin

Neal Sumerlin, retired Professor of Chemistry and founding Director of the Belk Observatory at Lynchburg College

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