Earth From the Outer Solar System

On July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft had the unusual opportunity to image the whole Saturn system as well as our home planet, Earth, and its moon. In this rare image, Earth is 898 million miles (1.44 billion kilometers) away and appears as a blue dot while the moon can be seen as a fainter protrusion off its right side. Opportunities to image Earth from the outer solar system are few and far between and special care must be taken to avoid damaging the cameras onboard the spacecraft. NASA informed the public about their planet’s portrait being taken from interplanetary distances and invited them to celebrate by finding Saturn in their part of the sky and waving at the ringed planet. This is one of many images that scientists will stich together to create a mosaic of the diffuse rings that encircle Saturn and check for change over time. The previous mosaic of the Saturn system captured by Cassini in 2006 revealed that the dusty E ring, which is fed by the water-ice plume of the moon Enceladus, had unexpectedly large variations in brightness and color around its orbit. Scientists want to see how the E ring looks seven Earth years later, in hopes that it will provide clues about the forces at work in the Saturn system.

See http://photojournal.jpl.nasa.gov/catalog/?IDNumber=PIA17171