Cassini is Going to Compose a Special Portrait of Saturn … and You!
By Linda Spilker
June 18, 2013
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.
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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
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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.
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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
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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).
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, will provide more information about where to look in the sky.
We've dedicated a special section of the Cassini website to this campaign and we hope you'll keep checking back at http://saturn.jpl.nasa.gov/waveatsaturn as the event approaches!
Linda Spilker is the Cassini project scientist, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
NASA
Guillermo Gonzalo Sánchez Achutgui
ayabaca@gmail.com
ayabaca@hotmail.com
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