swirling cloud cover.
Astronomers refer to Venus as Earth’s sister planet. Both are similar in size, mass, density
Earth’s at sea-level.
Venus is scorched with a surface temperature of about 482? C (900? F). This high
of carbon dioxide. Sunlight passes through the atmosphere to heat the surface of the planet.
Heat is radiated out, but is trapped by the dense atmosphere and not allowed to escape into
space. This makes Venus hotter than Mercury.
A Venusian day is 243 Earth days and is longer than its year of 225 days. Oddly, Venus rotates from east to west. To an
observer on Venus, the Sun would rise in the west and set in the east.
Developments in radar telescopes and radar imaging systems orbiting the planet have made it possible to see through the cloud
mission (1978), the Soviet Union’s Venera 15 and 16 missions (1983-1984), and NASA’s Magellan radar mapping mission
(1990-1994). As these spacecraft began mapping the planet a new picture of Venus emerged.
Venus’ surface is relatively young geologically speaking. It appears to have been completely resurfaced 300 to 500 million
years ago. Scientists debate how and why this occurred. The Venusian topography consists of vast plains covered by lava
flows and mountain or highland regions deformed by geological activity. Maxwell Montes in Ishtar Terra is the highest peak on
Venus. The Aphrodite Terra highlands extend almost half way around the equator. Magellan images of highland regions above
and cannot account for the bright highlands. One theory suggests that the bright material might be composed of metallic
compounds. Studies have shown the material might be iron pyrite (also know as “fools gold”). It is unstable on the plains but
would be stable in the highlands. The material could also be some type of exotic material which would give the same results but
at lower concentrations.
Venus is scarred by numerous impact craters distrubuted randomly over its surface. Small craters less that 2 kilometers (1.2
miles) are almost non-existent due to the heavy Venusian atmosphere. The exception occurs when large meteorites shatter just
surface is covered with volcanic rock. Hugh lava flows, extending for hundreds of kilometers, have flooded the lowlands
from volcanos have produced long sinuous channels extending for hundreds of kilometers, with one extending nearly 7,000
kilometers (4,300 miles).
Giant calderas more than 100 kilometers (62 miles) in diameter are found on Venus. Terrestrial calderas are usually only
several kilometers in diameter. Several features unique to Venus include coronae and arachnoids. Coronae are large circular to
mantle upwelling. Archnoids are circular to elongated features similar to coronae. They may have been caused by molten rock
seeping into surface fractures and producing systems of radiating dikes and fractures.