MAIN IDEA AND DETAILS
When you see a new
heading, remember to take
notes about important ideas.
Volcanoes shape the surface of Venus.
The planet Venus is only a little smaller than Earth and orbits a little
closer to the Sun. As a result, Venus is sometimes called Earth’s sister
planet. However, Venus is different from Earth in important ways.
Venus takes about eight months to turn just once on its axis.
Unlike most other planets, Venus rotates and orbits in opposite directions. The rotation and orbit together produce very long days and
nights—two months of daylight followed by two months of darkness.
Thick clouds make it
impossible to see Venus’s
surface in visible light.
This inset shows a map of
Venus that scientists made
using radio waves.
The atmosphere of Venus is very dense. Air pressure on Venus is
90 times that on Earth. Venus’s atmosphere is mostly carbon dioxide.
This gas slows the loss of energy and makes the surface very hot.
The ground temperature on Venus is about 470°C (about 870°F). The
atmosphere of Venus moves energy around so well that the long nights
are as hot as the days and the poles are as hot as the equator. In addition, there are droplets of sulfuric acid, a corrosive chemical, in the
atmosphere. These droplets form thick white clouds that completely
cover the planet and hide the surface.
Like Mercury, Venus is affected by the same four types of processes
that change Earth’s surface. Scientists think that tectonics and volcanism
may still be changing Venus’s surface today.
Patterns of cracks and cliffs have formed as movements of
the hot mantle have stretched, wrinkled, and twisted the surface.
Tectonics
Most of the surface of Venus has been covered with lava in the last billion years or so. Volcanoes
and flat lava plains are found all over the surface.
Volcanism
Venus
Venus is nearly the size of Earth but has a thicker atmosphere
and is much hotter than Earth. The surface is rocky, as you can
see in the image below.
Mass 82% of Earth’s mass
Diameter 95% of Earth’s diameter
Average distance from Sun 0.72 AU
Orbits in 225 Earth days
Rotates in 243 Earth days
weathered and eroded rock
spacecraft
666 Unit 5: Space Science