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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.
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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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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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).
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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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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.
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NASA
NASA Interplanetary Probes to Take Pictures of Earth
from Space
WASHINGTON -- Two NASA spacecraft, one studying the Saturn system, the other
observing Mercury, are maneuvering into place to take pictures of Earth on July
19 and 20.
The image taken from the Saturn system by NASA's Cassini spacecraft will
occur between 5:27 and 5:42 p.m. EDT (2:27 and 2:42 PDT or 21:27 and 21:47 UTC)
Friday, July 19. Cassini will be nearly 900 million miles away from Earth. NASA
is encouraging the public to look and wave in the direction of Saturn at the
time of the portrait and share their pictures via the Internet.
The Cassini Earth portrait is part of a more extensive mosaic -- or
multi-image picture -- of the Saturn system as it is backlit by the sun. The
viewing geometry highlights the tiniest of ring particles and will allow
scientists to see patterns within Saturn's dusty rings. Processing of the Earth
images is expected to take a few days and processing of the full Saturn system
mosaic will likely take several weeks.
Inspired in part by the Cassini team's plans to obtain a picture of Earth,
scientists reexamined the planned observations of NASA's MESSENGER spacecraft in
orbit around Mercury. They realized Earth is coincidentally expected to appear
in some images taken in a search for natural satellites around Mercury on July
19 and 20. Those images will be taken at 7:49 a.m., 8:38 a.m. and 9:41 a.m.
(11:49, 12:38 and 13:41 UTC) on both days. Parts of the Earth not illuminated in
the Cassini images, including all of Europe, the Middle East and Central Asia,
will appear illuminated in the MESSENGER images. MESSENGER's images also will
take a few days to process prior to release.
Details on how to find Saturn in the sky and participate in the event are
available at:
The public can share their pictures by using the hashtag #waveatsaturn on
Twitter, or uploading pictures to the event's Flickr page at:
The event's Facebook page is:
Cassini mission scientists also will be participating in a live Ustream show
on Friday from 5 to 5:30 p.m. EDT (2 to 2:30 p.m. PDT):
For more information about the two NASA spacecraft, visit:
and
- Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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