Transcript 11venus2s
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 Retrograde Rotation Rotation Rate Venus rotates on its axis with a period of 243 days Day is longer than a year Reason is unclear Venus from Pioneer 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 Structure of Atmosphere 68 km and up -- Temperature: 48-68 km – 30-40 km – 0-30 km – Pressure: 90 atmospheres at surface Temperature in 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 Venera 13 Mock-up Venera 13 on Venus The Surface of Venus Chemical analysis indicates that surface rocks are similar to basalt, a volcanic rock Interlude Planetary Configurations 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) Radar Map of Venus 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 Gula Mons Vires-Akka Chasma Alcott Crater A Corona Lava Domes The Highlands of Aphrodite Terra Danu Mountains Wind Blown Streak Sif Mons 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