Taking the Very Long View: Cassini Spacecraft Spots Venus…from Saturn

By Corey S. Powell | March 4, 2013 12:39 pm

Robotic spacecraft have done an amazing job of expanding human understanding of the worlds of the solar system, and few have done more to aid the cause than the Cassini probe that has been orbiting Saturn since June 30, 2004. Among its astonishing discoveries: lakes of frozen natural gas on Titan, icy geysers on Enceladus, and bizarre hexagonal storms circling Saturn’s north pole. DISCOVER recently featured a guided tour of Cassini pictures, curated by the mission’s top imaging expert, Carolyn Porco.

Venus is the speck of light behind Saturn’s rings, which look odd because they are lit from behind. Cassini was 500,000 miles from Saturn when it took this image. Venus was nearly a billion miles away. (Credit: NASA/JPL-Caltech/Space Science Institute)

But humanity’s far-flung emissaries have not just explored other worlds; they have also provided new perspectives on our place in space, by staring across the vast geometry of our entire solar system. The latest example of this stunning achievement: A new image of Venus taken from Saturn.

The scene here is so unfamiliar that it requires a little decoding. At the moment of this snapshot, Cassini is located behind the night side of Saturn, looking back roughly toward the sun (the only way it can see Venus, since Venus is much closer to the sun than Saturn is). Most of Saturn is almost dark, lit only dimly by reflected light from the rings, except for a thin bright crescent at left. The rings appear odd because they are back-lit, seen only by scattered sunlight. And that one bright dot? That is Venus, reflecting sunshine off its brilliant white clouds, seen from roughly 900 million miles away.

The new Cassini image joins other stunning view of worlds from other worlds, including Earth and Jupiter together from Mars, Earth from Mars during sunset, a beautiful earlier Cassini shot showing Earth as a “blue dot”  behind Saturn’s rings, and the original “pale blue dot” view of Earth seen from Voyager 4 billion miles away, at the edge of the solar system–a look back across the entire realm of the planets.

The “Pale Blue Dot” image, made famous by Carl Sagan, is a view of Earth taken from Voyage 1 in 1990 all the way across the solar system. The streaks are scattered sunlight; the mottling of the background is an imaging artifact from the extreme magnification. (Credit: NASA/JPL)

Earth (dot above rings at left) seen from Saturn by the Cassini spacecraft. This is a mosaic of 165 images taken over 3 hours in September, 2006. (Credit: NASA/JPL/Space Science Institute)

Earth (dot) seen from Mars, the first image of our world ever taken from the surface of another planet. It was captured by the Mars Exploration Rover Spirit an hour before sunrise on March 8, 2004. (Credit: NASA/JPL/Cornell/Texas A&M)

Earth and Jupiter, together in the sky, seen from Mars by the Mars Global Surveyor spacecraft. The scale makes it tricky to get the proper perspective. Click to see the whole image, then know that Earth was 86 million miles away, but Jupiter was 600 million miles away. (Credit: NASA/JPL/Malin Space Science Systems)


Out There

Notes from the far edge of space, astronomy, and physics.

About Corey S. Powell

Corey S. Powell is DISCOVER's Editor at Large and former Editor in Chief. Previously he has sat on the board of editors of Scientific American, taught science journalism at NYU, and been fired from NASA. Corey is the author of "20 Ways the World Could End," one of the first doomsday manuals, and "God in the Equation," an examination of the spiritual impulse in modern cosmology. He lives in Brooklyn, under nearly starless skies.


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