High Latitudes

The familiar banded appearance of Jupiter at low and middle latitudes
gradually gives way to a more mottled appearance at high latitudes in this
striking true color image taken Dec. 13, 2000, by NASA's Cassini
spacecraft.

The intricate structures seen in the polar region are clouds of different
chemical composition, height and thickness. Clouds are organized by winds,
and the mottled appearance in the polar regions suggests more vortex-type
motion and winds of less vigor at higher latitudes.

The cause of this difference is not understood. One possible contributor
is that the horizontal component of the Coriolis force, which arises from
the planet's rotation and is responsible for curving the trajectories of
ocean currents and winds on Earth, has its greatest effect at high
latitudes and vanishes at the equator. This tends to create small, intense
vortices at high latitudes on Jupiter. Another possibility may lie in that
fact that Jupiter overall emits nearly as much of its own heat as it
absorbs from the Sun, and this internal heat flux is very likely greater
at the poles. This condition could lead to enhanced convection at the
poles and more vortex-type structures. Further analysis of Cassini images,
including analysis of sequences taken over a span of time, should help us
understand the cause of equator-to-pole differences in cloud organization
and evolution.

By the time this picture was taken, Cassini had reached close enough to
Jupiter to allow the spacecraft to return images with more detail than
what's possible with the planetary camera on NASA's Earth-orbiting Hubble
Space Telescope. The resolution here is 114 kilometers (71 miles) per
pixel. This contrast-enhanced, edge-sharpened frame was composited from
images take at different wavelengths with Cassini's narrow-angle camera,
from a distance of 19 million kilometers (11.8 million miles). The
spacecraft was in almost a direct line between the Sun and Jupiter, so the
solar illumination on Jupiter is almost full phase.

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, manages the Cassini
mission for NASA's Office of Space Science, Washington, D.C.

Credit: NASA/JPL/University of Arizona

For higher resolution, click here.