October 9, 2000
Cassini View of Jupiter from 81 million miles
"We have acquired startlingly sharp images of the planet in a variety of filters,
from the ultraviolet into the near infrared," said Cassini Imaging Science team
leader Carolyn C. Porco of the University of Arizona. The photo release has
special significance for Porco. "This is our first color image from Cassini and
my gift to John Lennon - one of
planet Earth's brightest stars, and a person who gave us all boundless joy,
pleasure and inspiration," Porco said. "I am pleased that I can celebrate his
birthday in this way," Porco said of the late Beatle. Lennon would have been
This color image of Jupiter was taken by the camera onboard NASA's Cassini spacecraft when it was 81.3 million
kilometers (50.5 million miles) from the planet. It is composed of images taken in the blue, green, and red regions of the
spectrum and is therefore close to the true color of Jupiter that one would see through an Earth-based telescope.
The image is remarkably similar to images taken by NASA's Voyager 1 and 2 spacecraft more than 21 years ago,
illustrating the stability of Jupiter's weather patterns. The parallel dark and bright bands and many other large-scale
features are quasi- permanent structures that survive despite the intense small-scale activity ongoing in the atmosphere.
The longevity of the large- scale features is an intrinsic property of the atmospheric flows on a gaseous planet such as
Jupiter, with no solid surface. Smaller features, such as those in the dark bands north and south of the equator, are
observed to form and disappear in a few days.
Everything visible on the planet is a cloud. Unlike Earth, where only water condenses to form clouds, Jupiter has several
cloud-forming substances in its atmosphere. The updrafts and downdrafts bring different mixtures of these substances up
from below, leading to clouds of different colors. The bluish features just north of the equator are regions of reduced
cloud cover, similar to the place where the Galileo atmospheric probe entered in 1995. They are called "hot spots"
because the reduced cloud cover allows heat to escape from warmer, deeper levels in the atmosphere.
Jupiter's moon Europa is seen at the right, casting a shadow on the planet. Scientists believe Europa holds promise of a
liquid ocean beneath its surface.
Cassini 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, Calif., manages the Cassini
mission for NASA's Office of Space Science, Washington, D.C.
Image Credit: NASA/JPL/University of Arizona