Venus

The bright and morning (evening) star.

Moon & Venus Morning of April 22, 2009 http://www.bar-jobservatory.com/Moonvenus.html

General Properties

• 2nd planet form Sun• Distance from Sun 0.72 AU• Radius: 6,051km or 0.95 Earths• Mass: 0.82 Earths• Density: 5.24 g/cm3

• Average Temperature: 740 Kelvin (~470 C or 880 F)

• Number of Moons: 0• Rotation: -243 days• Orbital Period: 226.5 days or 0.62 years.

Phases of Venus

• Inferior planet• Angular size changes• Brightness changes

Phases of Venus

• Evidence that Copernicus was correct.

• First observed by Galileo.

Alignments of Venus

http://planet-venus.info/index.php?document_id=100

Greatest Elongations

• Elongations occur when an inner planet's, like Venus, position in its orbital path is at tangent to the view from Earth.

• Greatest eastern elongation occurs in western sky

• Greatest western elongation occurs in morning sky.

http://planet-venus.info/index.php?document_id=710

Elongation of Venus & MercuryMarch 29, 2004

Credit & Copyright: Jimmy Westlake (Colorado Mountain College)

Atmosphere of Venus

• Venus has a thick cloudy atmosphere the prevents direct viewing of its surface.

Atmosphere of Venus• Venus has a very

thick carbon dioxide atmosphere with a surface pressure 90 times Earth’s

• Layer of Sulfuric acid.

• Slow rotation produces very weak Coriolis effect and little weather

Greenhouse Effect• Visible light passes

through atmosphere and warms planet’s surface.

• Surface heats up from incoming light.

• Surface reemits in shorter infrared waves.

• Atmosphere and absorbs this infrared light from surface, trapping heat.

Atmosphere of Venus

Runaway Greenhouse Effect

• Venus closer to Sun than Earth.

• Atmosphere is mostly carbon dioxide, a greenhouse gas.

Runaway Greenhouse Effect

• Runaway greenhouse effect would account for why Venus has so little water

What have we learned?

• What is Venus like today?– Venus has an extremely thick CO2

atmosphere– Slow rotation means little weather

• How did Venus get so hot?– Runaway greenhouse effect made Venus

too hot for liquid oceans– All carbon dioxide remains in

atmosphere, leading to a huge greenhouse effect

Landscapes of VenusRadar Mapping

Landscapes of VenusVenera Landers

Landscapes of VenusMagellan Mission

Volcanoes

Landscapes of VenusMagellan Mission

Volcanoes

Landscapes of VenusMagellan Mission

Impact Craters