Now Cassini catches bright Venus shining between the rings
Sen—We have grown used to being spoiled with splendid images from the Cassini space probe orbiting Saturn. The latest continue to take our breath away.
Pictures reminiscent of the "Pale Blue Dot" show Earth's inner neighbour Venus pictured through its giant sibling's magnificent rings.
Venus, shrouded in clouds that are highly reflective of sunlight, shines brilliantly in the spectacular images. The first, taken last November but only recently released, was produced when Cassini was in the shadow of gas giant Saturn.
This shielded its camera from direct sunlight, allowing it to look in the direction of the inner Solar System, capturing Venus in a backlit image of Saturn and its rings. This viewing angle is termed "high solar phase" by the mission specialists.
Separate images taken with red, green and blue filters were combined to make a true-colour photo of Saturn, its rings and Venus. The bright arc is Saturn's limb. Part of the rings is seen in silhouette against the face of Saturn, itself faintly illuminated by sunlight scattered by the rings. (You can see the full-sized image here).
Planetary scientist Carolyn Porco, leader of the Cassini imaging team, commented: "Venus, a lovely shining beacon of light, is sighted beyond the glories of Saturn and its rings by our loyal emissary trolling the frigid depths of Saturnian orbit."
January's image of Venus just beyond Saturn's limb. Credit: NASA/JPL-Caltech/Space Science Institute
Cassini's other shot of Venus was taken in January and shows it just beyond Saturn's limb, close to the giant planet's G ring, a thin ring that lies beyond its main system of rings, all made up of billions of icy particles. Also visible in the picture is the diffuse E ring which lies outside the G ring and which is formed from the spray from Saturn's geyser-spouting moon Enceladus.
Cassini, which arrived with Europe's piggybacking Huygens Titan probe in 2004 to explore Saturn, has previously managed to snap the Earth. In 2006, when Saturn blotted out the Sun, its camera was turned to take 165 separate images over a three-hour period. These were then processed to produce an aetherial and haunting result.
In Saturn's Shadow: The 2006 image of Saturn showing Earth as a dot (upper left) between the rings. Credit: NASA/JPL/Space Science Institute
Visible as a speck in a gap between the rings to the left of Saturn was distant Earth, shining from more than a billion kilometres away. The image also allowed the discovery of two previously unknown rings in the Saturn system.
As we have reported before, Carolyn played a part in a previous imaging of Earth from deep space. It occurred to her that Voyager 1 might be turned to view our home world as it headed through the Solar System in the 1980s.
Though she lacked sufficient clout at the time to achieve this herself, famed space populariser Carl Sagan came up with the same idea independently and persuaded NASA to make the manoeuvre. It became the Pale Blue Dot, one of the most influential pictures ever taken by a space probe.
The Earth-Moon system imaged from Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/Space Science Institute
Saturn is not the only planet from which Earth has been photographed. The HiRISE camera on NASA's Mars Reconnaissance Orbiter took its own remarkable image of our world and the Moon in 2007 when Earth was 142 million km from Mars.