This false-color image is a near-infrared map of lower-levelclouds on
the night side of Venus, obtained by the Near InfraredMapping
Spectrometer (NIMS) aboard the Galileo spacecraft as itapproached the
planet's night side on February 10, 1990. Bright sliversof sunlit high clouds
are visible above and below the dark, glowing hemisphere.The spacecraft
is about 100,000 kilometers (60,000 miles) above the planet.An infrared
wavelength of 2.3 microns (about three times the longestwavelength
visible to the human eye) was used. The map shows the turbulent,cloudy
middle atmosphere some 50-55 kilometers (30-33 miles) abovethe surface,
10-16 kilometers or 6-10 miles below the visible cloudtops.The red
color represents the radiant heat from the lower atmosphere(about 400
degrees Fahrenheit) shining through the sulfuric acid clouds,which
appear as much as 10 times darker than the bright gapsbetween clouds.
This cloud layer is at about -30 degrees Fahrenheit, ata pressure about
1/2 Earths surface atmospheric pressure. Near the equator,the clouds
appear fluffy and blocky; farther north, they are stretchedout into
East-West filaments by winds estimated at more than 150mph, while the
poles are capped by thick clouds at this altitude.
This is the first image of a planet taken by NIMS duringits nine-year
mission. It is also the first near-infrared image everacquired of Venus from
a spacecraft, and reveals clouds details never seen before.orsince.
This is the only image ever taken which clearly shows theturbulent cloud
layer over the whole planet from pole to pole.
The Near Infrared Mapping Spectrometer (NIMS)on the Galileo
spacecraft is a combined mapping (imaging) and spectralinstrument. It can
sense 408 contiguous wavelengths from 0.7 microns (deepred) to 5.2 microns,
and can construct a map or image by mechanical scanning.It can
spectroscopically analyze atmospheres and surfaces andconstruct thermal and
chemical maps. Designed and operated by scientists andengineers at the Jet
Propulsion Laboratory, NIMS involves 15 scientists in theU.S., England, and
France. The Galileo Project is managed for NASA's Officeof Space Science and
Applications by JPL; its mission is to study the planetJupiter and its
satellites and magnetosphere after multiple gravity assistflybys at Venus and
the Earth.
Information provided to Chris Baines by Dr. Kevin Baines, Planetary Scientist,Jet Propulsion Laboratory, Pasadena, California.