Thursday, July 25, 2013

The Earth-Moon seen by Cassini Saturn and Mercury system and ... - Futura Sciences

This image was obtained from several photographs taken by the Cassini spacecraft July 19, 2013, at a distance of about 1,212,000 km from Saturn, and approximately 1.445.858.000 km from Earth. The scale representation of Saturn is 69 km per pixel, and the Earth is 86,620 km per pixel. This means that the Moon and the Earth does not appear as separate items on this picture. © NASA, JPL-Caltech, Space Science Institute

Earth-Moon system seen by Cassini Saturn and Mercury and Messenger – 2 Photos

When we see the images posted in recent days by NASA and taken July 19, 2013 by Cassini around Jupiter and Mercury Messenger around, one can not help thinking Carl Sagan. Indeed came to mind Pale Blue Dot (“pale blue dot” in French), a famous photograph of the Earth taken by the Voyager 1 probe February 14, 1990, and above all also famous video and a book by Carl Sagan incentive to reflect on the place of man in the cosmos.

The photograph that Voyager 1 was sent to Earth as it appeared showed the 6.4 billion kilometers (more than 42 AU) away, that is to say just “pale blue dot”, almost lost in the glare of the Sun. Those on which mankind may meditate today are similar. They show the Earth and the Moon seen as a single point off the rings of Saturn, and two distinct points in the vicinity of Mercury. The first was taken by the Cassini spacecraft at about 1.5 billion kilometers from Earth July 19, 2013, and the second shows the Earth-Moon system, but decided this time, the same day on an image taken by the Messenger probe to 98 million kilometers from Earth.

left, the unresolved issue of the Earth-Moon system made by Cassini image and right, that solved taken by Messenger. Cassini was able to take this picture because the sun was temporarily behind Saturn. Messenger on image, the Earth and Moon each measure less than one pixel in reality, but seem very large because they are overexposed. A long exposure is necessary to capture as much light as possible from potentially faint objects. Consequently, objects in the visual field become saturated and appear artificially large. Space Science Institute , Johns Hopkins University Applied Physics Laboratory , Carnegie Institution of Washington

“The Cassini image reminds us how our planet is tiny in the vastness of space, and it also demonstrates the ingenuity of the inhabitants of this small planet who sent so far from home to study Saturn and take a picture of the Earth “ robotic spacecraft, said Linda Spilker. And chief scientist of the Cassini at JPL added that “we can not see the continents individually or people in this portrait of the Earth, but this pale blue dot is a brief summary of what we were 19 July 2013 “.

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Lamont-Doherty Earth Observatory , chief scientist of the Messenger mission, images taken by the probe close to Mercury and Saturn Cassini around him inspire reflection: “Because Mercury and Saturn are different learning outcomes and evolution of planets, these two images also highlight what is special about the Earth. There is no place like our home.


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