Venus VENUS

When and where can you see it? Visible up to three hours after sunset or before sunrise. Often called the “morning” or “evening” star. Third brightest object in the sky. 10 times brighter than Sirius. Can be seen in the daytime, if you know where to look. On a moonless night, it casts a shadow!

Why is it so bright? It is highly reflective! 70% of the light it received is reflected. (Only 10% of the light reaching the moon or Mercury is reflected.)

Physical Properties At its closest approach to Earth, Venus is 0.72 AU from the sun. It’s radius is about.95 Earth radii. It has a mass of 4.9 x kg or 0.82 Earth mass.

Spacecraft visits 1975: Soviet’s Venera 9 and 10: landed on Venus; determined that the surface was dry and dusty; each only lasted an hour, as they overheated 1979: Pioneer Venus – took photographs

Temperature Averages 730 K (850 ˚F)

Surface Features Relatively smooth. Contains two continent-sized features (Ishtar Terra and Aphrodite Terra) contain mountains. Surface contains much basalt.

Volcanism and Cratering Contains many pancake shaped lava domes. Contains mostly shield volcanoes. May still have active volcanoes, evidenced by fluctuations in the amount of sulfur gases in the atmosphere.

Atmospheric Features Some of its clouds orbit the planet in only 4 Earth days, much faster than the planet rotates. Is 90 times more massive than Earth. Consists mostly of carbon dioxide; also contains sulfuric acid. Atmosphere is so thick that it does not allow small meteors through.

The Greenhouse Effect on Venus Its atmosphere is very thick – much thicker than Earth’s. It contains a lot of carbon dioxide, a greenhouse gas.

Rotation Rates Rate of rotation: 243 days Venus experiences retrograde rotation. That is, the sun rises in the west and sets in the east. Why does it rotate backwards? Early in its formation, it was struck by a large object. Rate of revolution: 225 days