Follow this link to skip to the main content

Wave at Saturn -- Introduction

Wave at Saturn banner art


Wave at Saturn -- Introduction

Cassini is Going to Compose a Special Portrait of Saturn … and You!

By Linda Spilker
June 18, 2013

One of the most exciting Cassini events in 2013 will be the unusual opportunity on July 19 to image the whole Saturn system as it is backlit by the sun. With Saturn covering the harsh light of the sun, we will be gathering unique ring science and also catching a glimpse of our very own home planet.

The main science goal for the mosaic we are making of the Saturn system is to look at the more diffuse rings that encircle Saturn and check for change over time. A previous mosaic of the Saturn system Cassini made 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. We'll want to see how that looks seven Earth years and a Saturnian season later, giving us clues to the forces at work in the Saturn system. We'll do this analysis by collecting data from our visual and infrared mapping spectrometer, composite infrared mapping spectrometer and ultraviolet imaging spectrograph in addition to the imaging cameras.

But one of the best parts of the mosaic we're making on July 19 is that we'll be able to take a picture of Earth – and all of you -- from about 898 million miles (1.44 billion kilometers) away. The Earth will appear to be just a pixel, but you can see in this simulated close-up what parts of it will be illuminated.

A computer simulated  view of Saturn from Cassini on July 19.
This simulated view from NASA's Cassini spacecraft shows the expected positions of Saturn and Earth on July 19, 2013, around the time Cassini will take Earth's picture. Cassini will be about 898 million miles (1.44 billion kilometers) away from Earth at the time. That distance is nearly 10 times the distance from the sun to Earth. Image credit: NASA/JPL-Caltech

Opportunities to image Earth from the outer solar system are few and far between and special care must be taken so we don't blind our cameras by looking in the direction of the sun, where Earth is. There have been only two images of Earth from the outer solar system in all the time humankind has been venturing out into space. The first and most distant was one was taken 23 years ago by NASA's Voyager 1 spacecraft from 4 billion miles (6 billion kilometers away), showing Earth as a pale blue dot . The other opportunity was Cassini's image in 2006 from 926 million miles (1.49 billion kilometers).

A computer simulated,  close-up view of Earth from Cassini on July 19.
North America and part of the Atlantic Ocean are expected to be illuminated when NASA's Cassini spacecraft takes a snapshot of Earth on July 19, 2013. This view is a close-up simulation. Image credit: NASA/JPL-Caltech

We think Cassini's July image is a special opportunity for Earthlings to wave at our photographer in the Saturn system and learn more about my favorite planet, its rings and moons. We hope you'll go outside, look in the direction of Saturn and send us pictures of yourselves waving. You can share your pictures by joining our Flickr group Wave at Saturn, adding them to our Wave at Saturn Facebook event page or tagging pictures on Twitter #waveatsaturn. We hope to make a special collage of all these images if we get enough of them.

The Cassini portrait session of Earth will last about 15 minutes from 2:27 to 2:42 p.m. PDT (21:27 to 21:42 UTC).

Another blog post by Jane Houston Jones, provides more information about where to look in the sky.




Linda Spilker is the Cassini project scientist, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.