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A closer look reveals a planet ¾ -covered with liquid water

A closer look reveals a planet ¾ -covered with liquid water. Earth’s interior is revealed by seismology, the study of earthquakes. Layers are revealed:. A layered object: Inner core Outer core Mantle Crust Hydrosphere Atmosphere Magnetosphere.

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A closer look reveals a planet ¾ -covered with liquid water

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  1. A closer look reveals a planet ¾ -covered with liquid water

  2. Earth’s interior is revealed by seismology, the study of earthquakes. Layers are revealed: A layered object: Inner core Outer core Mantle Crust Hydrosphere Atmosphere Magnetosphere

  3. Global Plates move slowly on top of the crust (plate tectonics). The motion at their boundaries causes earthquakes.

  4. Earth’s Magnetosphere varies in size, depending on the solar wind.

  5. Regions of radiation, calledVan Allen Belts, are named after James Van Allen of the Univ. of Iowa, who sent instruments up on early U.S. spacecraft. link

  6. Chapter 9: Cratered Worlds -The Moon and Mercury

  7. Earth’s interior is revealed by seismology, the study of earthquakes. Layers are revealed: A layered object: Inner core Outer core Mantle Crust Hydrosphere Atmosphere Magnetosphere

  8. Earth’s Moon: the interior is not as well understood Missing: Hydrosphere Atmosphere Magnetosphere

  9. Full Moon, Near Side

  10. Impact Basin Cratered Highlands Two Faces of the Moon Maria Near Side Far Side

  11. Lunar Tides are due to the gravity of the Moon

  12. Solar and Lunar effects on Tidesdepend on the relative orientations of the Earth, Moon, and Sun(see OpenStax- section 4.6)

  13. The tidal bulge is actually offset somewhat from being directly underneath the Moon. This produces a torque, a kind of twisting force on the Earth. The tides cause the Earth to slow down and the Moon’s orbit to increase in radius (4 cm per century). Also, the Moon’s rotation is synchronous with its orbit.

  14. The Moon’s formation is believed to be due to a collision of a massive (Mars-sized) object with the early Earth. Computer simulation show that this could leave a moon-sized satellite in the correct orbit.

  15. Data for the Terrestrial Planets

  16. Terrestrial Planets’ Spin Axis and Rotation Rate

  17. Terrestrial Planets’ Spin Mercury’s sidereal rotation is tidally locked to 2/3 of an orbit. Venus rotates very slowly backwards compared to the other Planets, so that it is rotating clockwise (others are CCW). Mercury and Venus both have almost no axial tilt, Earth and Mars both have similar axial tilts and rotation rates.

  18. Mercury’s Rotation is tidally locked to the orbital revolution period (the Mercury-year).The solar day on Mercury is 176 days long, which is two Mercury-years! See following slides for details.

  19. During the Mercury-year the planet rotates 1.5 times with respect to the stars, but only half of a solar day. For an observer at the location of the arrow, noon to sunset would take 44 Earth-days. After 88 Earth-days the observer would experience midnight (next slide).

  20. During the Mercury-year the planet rotates 1.5 times with respect to the stars, but only half of a solar day. For the observer, midnight to sunrise would take another44 Earth-days. Then after another 44 Earth-days the observer would experience noon(day 176, next slide).

  21. So it takes two Mercury-years for the planet to rotate througha solar day. This solar day lasts 176 Earth-days. Mercury orbits the sun in 88 Earth-days.

  22. Mercury’s Rotation is tidally locked to the orbital revolution period.The solar day on Mercury is 176 days long, which is two Mercury-years! This tidal locking is different from that of the Moon revolving around Earth because Mercury’s orbit is elliptical and not nearly circular like the Moon’s.

  23. Atmospheres and Temperatures Mercury has no atmosphere, just like our moon. Because there is no atmosphere to trap heat, the night side of Mercury gets very cold (100 K or -280oF). The day side of Mercury gets up to 700 K (or 800oF). The atmosphere of Venus is made up of carbon dioxide, with clouds of sulfuric acid. The atmosphere is some 90 times denser than Earth’s. The Greenhouse effect causes the surface temperature of Venus to be close to 730K (or 860oF) day or night. Mars has a very thin atmosphere (less than 1% of Earth’s) of mainly carbon dioxide. The surface temperature is approximately 50 K (50oC) lower than Earth’s.

  24. Mercury Maps and images • USGS has a website with planet maps • http://astrogeology.usgs.gov/maps/planetary-maps-and-globes • These can provide tennis ball projects for kids • http://planetarynames.wr.usgs.gov/Page/mercuryQuadMap • Newer results have resulted from the MESSENGER spacecraft. • Launched in August 2004, the Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, known as MESSENGER, entered into orbit around Mercury in 2011. The following photos are from this spacecraft.

  25. Terrestrial Planet Magnetic Fields Mercury has a very weak magnetic field, partly due to its slow rotation, even though it may have liquid iron in the core. Venus has no measurable magnetic field, probably due to its very slow rotation rate. Mars has a magnetic field weaker than Mercury, meaning that its core is either not liquid or not metallic.

  26. Ch. 10: Earthlike Planets: Venus and Mars

  27. Terrestrial Planets’ Spin Axis and Rotation Rate.Venus and Mercury have no tilt; Mars is tilted like Earth.

  28. Terrestrial Planets’ Spin Mercury’s sidereal rotation is tidally locked to 2/3 of an orbit. Venus rotates very slowly backwards compared to the other Planets, so that it is rotating clockwise (others are CCW). Mercury and Venus both have almost no axial tilt, Earth and Mars both have similar axial tilts and rotation rates.

  29. Atmospheres and Temperatures Mercury has no atmosphere, just like our moon. Because there is no atmosphere to trap heat, the night side of Mercury gets very cold (100 K or -280oF). The day side of Mercury gets up to 700 K (or 800oF). The atmosphere of Venus is made up of carbon dioxide, with clouds of sulfuric acid. The atmosphere is some 90 times denser than Earth’s. The Greenhouse effect causes the surface temperature of Venus to be close to 730K (or 860oF) day or night. Mars has a very thin atmosphere (less than 1% of Earth’s) of mainly carbon dioxide. The surface temperature is approximately 50 K (50oC) lower than Earth’s.

  30. Venus, Up Close Because of Venus’s dense cloud cover most of what we know about Venus’s surface and rotation comes from using radar. There have been only a few spacecraft to land on Venus, but each survived for only a short time. (This is an ultraviolet photo.)

  31. Venus Radar Map taken by the Pioneer Venus spacecraft

  32. Earth Radar Map, shown with scale similar to the Venus map

  33. Venus map made by the Magellan spacecraft In 1995 the Magellan spacecraft was able to make a much more detailed radar map of Venus. Possibly active shield volcanoes, craters, and volcanic structures called coronae were seen by Magellan.

  34. Venus surface, taken with a camera on the Soviet “Venera” probe (“Venera” just means “Venus” in Russian).

  35. Terrestrial Planet Interiors Mercury’s mantle is solid (not semi-molten like the Earth’s) and its iron core may have a solid center. There should be a liquid iron layer which causes the magnetism of Mercury. Not much is known about the interior of Venus – but it is thought to be like a young Earth. (so we don’t have a figure for it above) Mars is mostly solid and no longer geologically active in any way.

  36. Earth’s Magnetosphere is due to it’s magnetism. The Earth’s magnetic field is formed because of the Earth’s fairly rapid rotation and because the Earth has a molten iron outer core which can flow and can have electric currents in it. There is no Lunar magnetic field so it has little iron.

  37. Terrestrial Planet Magnetic Fields Mercury has a very weak magnetic field, partly due to its slow rotation, even though it may have liquid iron in the core. Venus has no measurable magnetic field, probably due to its very slow rotation rate. Mars has a magnetic field weaker than Mercury, meaning that its core is either not liquid or not metallic.

  38. Mars Globe, showing some major features

  39. Mars atmosphere • The atmosphere is almost all carbon dioxide. Specifically, it is 96% carbon dioxide (CO2), 1.9% argon (Ar), and 1.9% nitrogen (N2). • There are trace amounts of O2, CO, H2O and CH4. • The pressure varies but is less than 1% of the pressure on the surface of Earth. • Variation in pressure is due to the condensation of carbon dioxide on the polar ice caps. • Dust is also an important feature of the atmosphere. • The MAVEN spacecraft is studying the atmosphere.

  40. Martian sunset – we see a blue sky, due to scattering, with little absorption of blue

  41. Dust storms can cover the entire planet.

  42. Mars Ice Caps • The ice caps are mostly frozen water but contain large amounts of carbon dioxide on a seasonal basis. • The carbon dioxide condenses directly out of the atmosphere, similar to frost, and removes about a quarter of the atmosphere’s gases each winter season. • The southern ice cap has continuous carbon dioxide ice due to being at higher altitude. • The next slide shows the northern ice cap.

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