The cameras on NASA's Cassini
spacecraft captured this rare look at Earth and its moon from Saturn orbit on
July 19, 2013. Taken while performing a large wide-angle mosaic of the entire
Saturn ring system, narrow-angle camera images were deliberately inserted into
the sequence in order to image Earth and its moon. This is the second time that
Cassini has imaged Earth from within Saturn's shadow, and only the third time
ever that our planet has been imaged from the outer solar system.
Earth is the blue point of light on
the left; the moon is fainter, white, and on the right. Both are seen here
through the faint, diffuse E ring of Saturn. Earth was brighter than the
estimated brightness used to calculate the narrow-angle camera exposure times.
Hence, information derived from the wide-angle camera images was used to
process this color composite.
Both Earth and the moon have been
increased in brightness for easy visibility; in addition, brightness of the
moon has been increased relative to Earth, and the brightness of the E ring has
been increased as well.
Images taken using red, green and blue
spectral filters were combined to create this natural color view. (The
accompanying wide angle frame can be found at PIA17171.) The images were
obtained by the Cassini spacecraft cameras on July 19, 2013 at a distance of
approximately 898.414 million miles (1.445858 billion kilometers) from Earth.
Image scale on the Earth is 5,382 miles (8,662 kilometers) per pixel. The illuminated
areas of neither Earth nor the moon are resolved here. Consequently, the size
of each "dot" is the same size that a point of light of comparable
brightness would have in the narrow angle camera.
A close-up view of Earth and moon,
magnified by a factor of five is available at PIA17170.
The first image of Earth captured from
the outer solar system was taken by NASA's Voyager 1 in 1990 and famously
titled "Pale Blue Dot" (PIA00452). Sixteen years later, in 2006,
Cassini imaged the Earth in the stunning and unique mosaic of Saturn called
"In Saturn's Shadow-The Pale Blue Dot" (PIA08329). And, seven years
further along, Cassini did it again in a coordinated event that became the
first time that Earth's inhabitants knew in advance that they were being imaged
from nearly a billion miles (nearly 1.5 billion kilometers) away. It was the
also the first time that Cassini's highest-resolution camera was employed so
that the Earth and its moon could be captured as two distinct targets.
The Cassini-Huygens mission is a
cooperative project of NASA, the European Space Agency and the Italian Space
Agency. The Jet Propulsion Laboratory, a division of the California Institute
of Technology in Pasadena, manages the mission for NASA's Science Mission
Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras
were designed, developed and assembled at JPL. The imaging operations center is
based at the Space Science Institute in Boulder, Colo.
هیچ نظری موجود نیست:
ارسال یک نظر