ASTR 151 Chapter 9
Popular in Journey Thr Solar Sys Lecture
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This 3 page Class Notes was uploaded by Wesley Fowler on Thursday April 21, 2016. The Class Notes belongs to ASTR 151 001 at a university taught by Dr. Sean Lindsay in Spring 2016. Since its upload, it has received 15 views.
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Date Created: 04/21/16
Wesley Fowler ASTR Chapter 9 Venus nd Distance from Sun: 0.72 AU (2 planet from the Sun) Radius: 6,052 km (0.95 Earth radii) Mass: 4.87 x 10 kg (0.815 Earth Masses) 3 Average Density: 5,250 kg/m (Implies differentiated) Rotational Period: -243.0 days Venus rotates CLOCKWISE Solar Day (Noon-to-Noon Day): 117 days o o Axial Tilt: 177.4 (to orbit, or 2.64 and retrograde rot.) Mean Temperature: 740 K (464 C or 870 F) o Surface Pressure: 92 bar (Earth is 1 bar) Has an atmosphere Does not have a global magnetic field: Very slow rotation Venus has an albedo of 0.7 Albedo: The amount of light reflected by an object (0-1) - 0 would be a perfect black body - 1 would perfectly reflect all light Venus’ Orbit Orbits close to the sun, always appearing close to the Sun from Earth. Maximum distance is 47° - 3 brightest object in the sky next to the Sun and Moon - Has a full set of phases, observed by Galileo - Appears bigger in the sky when it orbits close to Earth Venus is the only planet with retrograde rotation - Axial Tilt of 177.4° Day is longer than the year. Rotational Period: 243.0 days Solar Day: 117 days (noon-to-noon) Orbital Period: 222 days Covered by very thick atmosphere, mostly comprised of CO 2 - Surface temperature of ~740K - Super-rotating atmosphere: Encircles Venus in about 4 days Venus’ Surface Very young surface, about 300-600 million years old. Doesn’t have many impact craters - Crater counting dates Venus’ surface as very young, from 300 million years to just under a billion years. - Two continent-sized highlands: Ishtar Terra and Aphrodite Terra. Cover 8% of surface - Mostly flat lowlands - No plate tectonics, but has 167 volcanoes - Can only be observed by using Radio or Infrared wavelengths Lakshmi Planum: Most prominent feature on Ishtar Terra, large plateau 1500 km across. Ovda Regio: The dominate feature of Aphrodite Terra, two ridges running in different directions. Maxell Monvccc s: Largest mountain/volcano on Venus, a shield volcano Venus’ Volcanism Shield Volcanoes: Low profile, wide based volcanoes. - Calderas: Impressions on the top of shield volcanoes - All of Venus’ volcanoes are shield volcanoes The cracks on Venus, often associated with lava flow, are indicative of a convective mantle. Lava Domes: Circular impression on Venus, formed by the collapse of domes formed by lava - Unique to Venus - Usually located near coronae Coronae: Venus’ largest volcanic features, they are super lava domes. Huge circular lava regions. (100s-1000s km in diameter) Likely produced by mantle convection. Volcanism is still presently active on Venus. 1. Large fluctuation of sulfur dioxide above Venus’s clouds 2. Bursts of radio activity are similar to bursts have been observed on Earth 3. Large surface temperature variations on the order of days associated with known volcanic rift zones. Almost certainly active lava flows on the surface. Venus’ Atmosphere 90x the mass of Earth’s atmosphere, and has a much simpler design. - Troposphere goes up to 100km above the surface - Highly reflective sulfuric clouds between 50-70 km - Has no asthenosphere Super-rotating wind: 300-400 km/hr “jet stream” - Faster than the planet’s orbital rotation Below the haze are clear skies, sluggish air. Composition: CO 2Carbon Dioxide) 96.5% N 2(Nitrogen) 3.5% - Top layer of clouds is made of sulfuric acid The high amount of carbon dioxide causes the atmosphere to absorb and reradiate around 99% of all infrared radiation released from the surface. This causes an extreme greenhouse effect on Venus. Earth and Venus shared a similar secondary atmosphere: Carbon dioxide, sulfur dioxide, water, and nitrogen compounds. - If Earth didn’t have oceans, it would probably have Venus’s atmosphere. Venus receives twice as much energy from the Sun because it’s 30% closer to it. - Causes oceans to first evaporate, thus atmosphere thickens, thus temperature increases. Runaway Greenhouse Effect: The process of a planet’s surface temperature and atmospheric opacity contributing to the increase in the greenhouse effect.
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