Pale Blue Dot Shines In Cassini, MESSENGER Images
July 23, 2013

NASA Releases Earth Images Taken From Saturn And Mercury

Brett Smith for - Your Universe Online

It might look like just one pale blue dot among millions of other similar looking objects, but NASA's Cassini spacecraft recently captured an 'Earth-selfie' from 890 million miles away.

The image captured by the Saturn orbiter is actually a look into the past as light from Earth takes 80 minutes to reach the ringed planet.

"We can't see individual continents or people in this portrait of Earth, but this pale blue dot is a succinct summary of who we were on July 19," said Linda Spilker, Cassini project scientist, at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "Cassini's picture reminds us how tiny our home planet is in the vastness of space, and also testifies to the ingenuity of the citizens of this tiny planet to send a robotic spacecraft so far away from home to study Saturn and take a look-back photo of Earth."

Scientists rarely take photos of Earth from Cassini's distance or beyond because the Earth appears so close to the sun from that vantage point. Just like the human eye, a craft's imaging equipment could be permanently damaged by looking directly at the sun. Cassini was able to capture this image by essentially using Saturn's shade to protect its camera.

NASA said they will be using the selfie as part of a larger photo mosaic of Saturn's rings, expected to be released in several weeks.

"It thrills me to no end that people all over the world took a break from their normal activities to go outside and celebrate the interplanetary salute between robot and maker that these images represent," said Carolyn Porco, Cassini imaging team lead at the Space Science Institute in Boulder, Colo. "The whole event underscores for me our 'coming of age' as planetary explorers."

NASA also announced MESSENGER, the first craft to orbit Mercury, took a black-and-white picture of Earth from 61 million miles away as part of an operation to search for natural satellites of the planet closest to the sun. Both the Earth and moon are less than a pixel in the MESSENGER image, but appear larger due to an overexposure technique designed to make dim object appear saturate with light.

"That images of our planet have been acquired on a single day from two distant solar system outposts reminds us of this nation's stunning technical accomplishments in planetary exploration," said MESSENGER principal investigator Sean Solomon from Columbia University. "And because Mercury and Saturn are such different outcomes of planetary formation and evolution, these two images also highlight what is special about Earth. There's no place like home."

Cassini completed its initial four-year mission to survey Saturn and the objects orbiting it in 2008. It is currently on its extended Solstice Mission, which is scheduled to last until 2017. In May 2017, the planet will reach its summer solstice - or the beginning of summer in Saturn's northern hemisphere and winter in its southern hemisphere. Because Cassini arrived just after the winter solstice, the extended mission will allow NASA to study a complete seasonal period on Saturn.