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Venus. Astronomy 311 Professor Lee Carkner Lecture 11. Venus -- The Goddess of Beauty. Venus is one of the brightest planets in the sky. Venus from Earth. Venus is only seen near the Sun Venus shows phases Venus is covered with clouds. Venus Facts. Size : 95% Earth Orbit : 0.7 AU
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Venus Astronomy 311 Professor Lee Carkner Lecture 11
Venus -- The Goddess of Beauty • Venus is one of the brightest planets in the sky
Venus from Earth • Venus is only seen near the Sun • Venus shows phases • Venus is covered with clouds
Venus Facts • Size: 95% Earth • Orbit: 0.7 AU • Description:
Venus’s Retrograde Rotation • When viewed from above the north pole of the Earth, most of the planets: • Venus rotates clockwise • Why is Venus upside down? • We have no evidence of this, however
Rotation Rate • Venus rotates on its axis with a period of 243 days • Day is longer than a year • Reason is unclear
Venus’s Atmosphere • In the 1960’s and 1970’s probes were dropped into Venus’s atmosphere • Composition: • Pressure: • Temperature: 750 K (hottest planet in solar system)
Chemicals in Atmosphere • A lot of sulfur in atmosphere • Sulfuric acid has vapor point such that it boils on the surface but condenses in the atmosphere to form clouds • Also, hydrofluoric acid (HF), hydrochloric acid (HCl) and other corrosive compounds
68 km and up -- 48-68 km – 30-40 km – 0-30 km – Temperature: Pressure: 90 atmospheres at surface Structure of Atmosphere
Formation of Atmosphere 1) Early Venus heats up, water evaporates 2) 3) Ultraviolet light disassociates water and destroys it 4) 5) 6) Volcanoes outgas sulfur, forms sulfuric acid clouds
The Surface of Venus • Chemical analysis indicates that surface rocks are similar to basalt, a volcanic rock
Magellan Maps Venus • Venus’s atmosphere is so thick that you cannot see the surface from orbit • Our map of Venus comes from the Magellan spacecraft (1990)
Global Surface of Venus • Surface is generally level (smoothed by lava) • Many volcanoes and lava features • The entire surface is the same age • Surface features named after women
Volcanism on Venus • Evidence for Volcanism: • smoothed surface • lava channels • visible shield features
The Interior of Venus • No plate tectonics • moving lava disturbs the crust enough to produce a few mountains and highlands • too hot or too dry? • Venus probably has a molten core
Summary • Earth-Sized, hot, thick atmosphere • (Earth’s evil twin) • Rotates slowly and upside-down • Studied by Venera landers and Magellan radar mapper
Summary: Atmosphere • Composed of CO2 with sulfuric acid clouds • Thick (90 atmospheres) : • No water to wash out CO2 • Hot (750 K): • Powerful greenhouse effect
Summary: Surface • Volcanism shapes surface and outgases sulfur • See volcanoes and lava flow channels • Surface mostly flat with a few highlands • Nature of core is unknown