| Back | Map | Glossary | Information |
Venus: Optical View
The second nearest planet to the Sun, Venus is shrouded in a thick, highly corrosive layer of clouds made up mostly of sulfuric acid.
JPEG Image (22K); Caption and Credits
In fact, the night side appears "brighter" than the day side. This is because, in contrast to the reflected light seen at optical wavelengths, a radiotelescope operating in millimeter region detects the planet's thermal radiation. The temperature (hence "brightness") measured depends on the depth of the planet's atmosphere probed. As the atmospheric pressure mounts deeper down, the temperature increases, along with the "brightness" of the emissions picked up by the telescope.
Illustrated here is an image of 3 millimeter "continuum" or "broadband" radiation from the planet's atmosphere.
JPEG Image (20K);
Credits & Copyright
However, several types of molecules in Venus's atmosphere emit millimeter radiation at more specific
wavelengths and can be used as tracers to probe the atmosphere. By taking advantage of the BIMA array's excellent
spectroscopic resolution, researchers can measure the motions, densities, and other physical characteristics of the clouds.
Probing beneath the clouds, researchers are also studying surface emissions at other microwave frequencies. The results indicate that the surface temperature stays the same, night and day. Still other researchers are able to peer beneath the Venus's dense clouds and map its surface features with radar, beaming radio waves towards the planet, then analyzing the returning "echoes."
Venus in Ultraviolet
The ultraviolet image brings the thick clouds surrounding Venus into sharp relief.
Related studies indicate that the clouds travel quickly around the planet,
taking only four days to circulate once. In contrast, Venus itself rotates very slowly in the opposite direction,
taking 243 days to complete one revolution.
JPEG Image (42K);
Caption, Credits and Copyright
Venus in Infrared
This infrared image of Venus shows that, in addition to emitting greater microwave energy, roughly
equal amounts of heat are radiated by Venus at night than during the day, reflecting the powerful
"greenhouse" effect caused by the dense, carbon dioxide-rich atmosphere.
JPEG Image (44K);
Caption, Credits and Copyright
Venus: a Radar View
The radar image reveals that huge plains, punctuated by large numbers of meteorite
craters, cover most of Venus's surface. Separated by the plains,
volcanic regions contain a very large number of sizeable volcanoes. Scientists believe that some of the volcanoes
are active, spewing gases, including sulfurous compounds, into the atmosphere.
JPEG Image (78K); Caption, Credits and Copyright
Exhibit Map
Glossary
Information Center
