1 / 43

NATS1311 From the Cosmos to Earth

Mercury. NATS1311 From the Cosmos to Earth. NATS1311 From the Cosmos to Earth. The orbit of Mercury At an average distance of only 58 million kilometers (36 million miles) from the sun, mercury takes a mere 88 days to go around its orbit.

kiele
Download Presentation

NATS1311 From the Cosmos to Earth

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mercury NATS1311 From the Cosmos to Earth

  2. NATS1311 From the Cosmos to Earth

  3. The orbit of Mercury At an average distance of only 58 million kilometers (36 million miles) from the sun, mercury takes a mere 88 days to go around its orbit. As viewed from earth, mercury can be seen only near times of greatest eastern or western elongation. At greatest western elongation (when the planet is farthest west of the sun in the sky), mercury rises about 1 1/2 hours before sunrise. At greatest eastern elongation (when the planet is farthest east of the sun in the sky), mercury sets about 1 1/2 hours after sunset. NATS1311 From the Cosmos to Earth

  4. NATS1311 From the Cosmos to Earth

  5. NATS1311 From the Cosmos to Earth Differences between the Moon and Mercury 1. Areas between craters on Mercury smoother than on Moon. 2. Secondary impact craters don't scatter as much on Mercury. 3. Gravitational acceleration on Mercury twice that of moon. 4. Mercury has scarps - lines of cliffs- caused by shrinkage of its surface. 5. Mercury's atmosphere consists of sodium and potassium (sputtered form surface by the solar wind), helium and oxygen. 6. Atmospheric pressure about the same as on the Moon.

  6. NATS 1311 From the Cosmos to Earth

  7. NATS 1311 From the Cosmos to Earth Fig.8.2 Figure 8.2 Surface views of the terrestrial worlds. No spacecraft have landed on Mercury, so an artist's conception is shown; all other images are photos.

  8. Atmosphere of Earth Blanket of Gases Surrounding Earth Contains a Mixture of Gases Composition of Dry Air NATS 1311 From the Cosmos to Earth • Pressure on a surface is weight of air above that surface • Pressure of 1 atmosphere at Earth’s surface at sea level: • 14.7 Lb. per Square Inch • 76 Cm of Mercury (30 inches of Mercury) • 1034 Grams per Square Centimeter • Pressure decreases as altitude above Earth’s surface increases

  9. Regions of the Atmosphere NATS 1311 From the Cosmos to Earth

  10. Figure 8.12 The structure of a generic planetary atmosphere: Solar X rays are absorbed in the thermosphere, ultraviolet light is absorbed in the stratosphere, and visible light reaches the ground. Planets that lack ultraviolet-absorbing molecules will lack a stratosphere, and planets with very little gas will have only an exosphere. NATS 1311 From the Cosmos to Earth Fig. 8.12

  11. NATS 1311 From the Cosmos to Earth Thermal structure of the atmosphere. Atmospheric temperature plotted as a function of altitude from ground level to 110 kilometers.

  12. NATS 1311 From the Cosmos to Earth

  13. NATS 1311 From the Cosmos to Earth Fig. 8.13 Figure 8.13 Atmospheric gases scatter blue light more than they scatter red light. During most of the day, you therefore see blue photons coming from most directions in the sky, making the sky look blue. But only the red photons reach your eyes at sunrise or sunset, when the light must travel a longer path through the atmosphere to reach you.

  14. NATS 1311 From the Cosmos to Earth Fig. 8.14 Figure 8.14 The greenhouse effect: The troposphere becomes warmer than it would be if it had no greenhouse gases.

  15. Figure 8.16 A planet's magnetosphere acts like a protective bubble that shields the surface from charged particles coming from the solar wind. Among the terrestrial planets, only the Earth has a strong enough magnetic field to create a magnetosphere. The Earth's magnetosphere allows charged particles to strike the atmosphere only near the poles, thereby creating the phenomena of the aurora borealis and aurora australis. NATS 1311 From the Cosmos to Earth Fig. 8.16

  16. VENUS NATS 1311 From the Cosmos to Earth Comparison of Venus and Earth Parameter Venus Earth • Distance from Sun (AU) .72 1.00 (million KM) 108 150 • Sidereal Period (year) (earth days) 225 365 • Rotation Period (day) (earth days) -243 1.00 • Direction of rotation Retrograde Direct • Equatorial Diameter 0.96 1.00 • Escape velocity (km/Sec.) 10.3 11.2 • Inclination of axis 3 23.5 • Seasons No Yes

  17. VENUS NATS 1311 From the Cosmos to Earth Comparison of Venus and Earth • Parameter Venus Earth • Surface Temperature 480C (900F) 15C (60F) • Surface atmospheric pressure 90 1 (atmospheres) • Atmospheric gases CO2 N2, O2 • Cloud cover Total Partial • Surface Solid 3/4 water • Number of satellites 0 1

  18. NATS1311 From the Cosmos to Earth

  19. NATS 1311 From the Cosmos to Earth

  20. VENUS NATS 1311 From the Cosmos to Earth • Venus clouds:  3 layers 49 to 65 km in altitude  haze down to 30 km  clear below 30km  composition: H2so4 droplets and sulfur particles • Venus surface: Rock strewn surface • Temperature: 480c (900f)

  21. NATS 1311 From the Cosmos to Earth VENUS Surface: • Venus: • No plate tectonics - (movement of surface) • Radioactive heating • Vocanoes are scattered over the surface of Venus • Crustal material is denser than the underlying magma • Every 500 million years, the crust breaks up andsinks, forming a new crust • Earth: • 1 0 plates - volcanoes found on plate boundaries

  22. Atmosphere Formation Original atmospheres were swept away from the terrestrial planets early in their life. Present day terrestrial atmospheres are secondary atmospheres: Venus: Formed by outgassing (volcanoes and gas seepage) from beneath the surface. Surface too warm for water to condense as a liquid - water dissociated into hydrogen and oxygen. Hydrogen escaped - oxygen combined with surface materials. NATS 1311 From the Cosmos to Earth

  23. NATS 1311 From the Cosmos to Earth Carbon dioxide and nitrogen accumulated in the atmosphere. CO2 96% N2 3-4% "Runaway" greenhouse effect. Earth: Water condensed into liquid form CO2 dissolved into the water - formed limestone rocks Nitrogen accumulated in the atmosphere Oxygen accumulated after life formed in the oceans Atmosphere Formation

  24. NATS 1311 From the Cosmos to Earth

  25. NATS 1311 From the Cosmos to Earth Differences between Venus and earth Venus rotation rate is very slow and in retrograde direction. Venus surface consists of 1 plate; earth has 9 plates. Venus has little or no magnetic field. Venus' atmosphere pressure is 90 times that of earth. Dominant gas in the Venus atmosphere is carbon dioxide. 6. Venus' surface temperature is 900° F. 7. Venus has very little water vapor in its atmosphere. 8 Venus has a very strong greenhouse effect. 9. There is no water on Venus' surface. 10. Venus has a very dense cloud cover.

  26. NATS 1311 From the Cosmos to Earth Fig. 8.26 Figure 8.26 The surface of Venus is covered with abundant lava flows and tectonic features, along with a few large impact craters. Because these images were taken by the Magellan spacecraft radar, dark and light areas correspond to how well radio waves are reflected, not visible light. Nonetheless, geological features stand out well. In (b), the data have been converted to a three-dimensional perspective view; heights are magnified by a factor of more than 20, so the volcano is not actually as steep-sided as it appears.

  27. NATS 1311 From the Cosmos to Earth Fig. 8.26

  28. NATS 1311 From the Cosmos to Earth Fig. 8.26 Figure 8.26 Two of Venus's relatively rare impact craters. (b) Shield volcanoes like this one are common on Venus. (Height exaggerated to show detail.) (c) Tectonic forces have fractured and twisted the crust in the region. (d) The circular cracks and volcanic bumps make up a corona, probably caused by the pressure of a mantle plume below.

  29. NATS 1311 From the Cosmos to Earth • Mars • Comparison of Venus, Earth and Mars • Parameter Venus Earth Mars • Distance from Sun (AU) .72 1.00 1.52 (million KM) 108 150 228 • Sidereal Period (year) (earth days) 225 365 687 • Rotation Period (day) (earth days) -243 1.00 1.03 • Direction of rotation Retrograde Direct Direct • Equatorial Diameter 0.96 1.00 0.53 • Escape velocity (km/Sec.) 10.3 11.2 5.0 • Inclination of axis 3 23.5 25.2 • Seasons No Yes Yes

  30. NATS 1311 From the Cosmos to Earth • Mars • Comparison of Venus, Earth and Mars • Parameter Venus Earth Mars • Surface Temperature 480C (900F) 15C(60F) -60C(-76F) • Surface atmospheric pressure 90 1 1/200 • (atmospheres) • Atmospheric gases CO2 N2, O2 CO2 • Cloud cover Total Partial Rare • Surface Solid 3/4 water Solid • Number of satellites 0 1 2

  31. NATS 1311 From the Cosmos to Earth

  32. NATS 1311 From the Cosmos to Earth Viking Life Detection Experiments on Mars Living organisms alter their environment - they breathe, eat, grow, and produce waste Three experiments were designed to detect signs of living organisms by treating soil samples in a closed environment (a container):

  33. NATS 1311 From the Cosmos to Earth Viking Life Detection Experiments on Mars Gas exchange - Looked for changes in the atmosphere caused by metabolism of organisms in the soil. Soil sample fed nutrient in a carbon dioxide (co2) atmosphere. Organisms eat nutrients and release gases like CO2, methane, oxygen and hydrogen into the container. Some gases were found but were thought to be due to chemical reactions between the nutrient water and the soil.

  34. NATS 1311 From the Cosmos to Earth Viking Life Detection Experiments on Mars Labeled release - Looked for co2 breathed into the atmosphere Soil sample fed radioactive nutrient Organisms released radioactive CO2 into the container Some gases were found but were thought to be due to the chemical reactions between the nutrient and the soil

  35. Viking Life Detection Experiments on Mars Pyrolytic release - Looked for radioactive carbon in soil sample Soil sample in radioactive CO2 atmosphere illuminated by ultraviolet light to simulate sun light Soil sample then heated to 650°C to decompose any growth material in the soil Soil contained some radioactive carbon - did not represent life Conclusion: Some positive results found in each experiment. However, not sufficient to confirm life as we know it Explanation - unusual chemical activity NATS 1311 From the Cosmos to Earth

  36. NATS 1311 From the Cosmos to Earth • METEORITES FROM MARS • Meteorites found on antarctic ice • Concentrated in place where ice flows are impeded and the ice is ablated • Well preserved: Not exposed to water erosion Not exposed to industrial contaminants

  37. METEORITES FROM MARS Twelve antarctic meteorites came from Mars: • Called SNC meteorites • Age: 4.5 billion years • Ejected from Mars by collision of some large object (asteroid?) with Mars • Spent several million years in orbit, then landed on earth • Discovered within the last 20 years • Why from Mars? Trapped gases in voids in the meteorites match martian atmosphere NATS 1311 From the Cosmos to Earth

  38. NATS 1311 From the Cosmos to Earth • ALH 84001 METEORITE • Formed 4.5 billion years ago • Ejected from Mars 1 6 million years ago • Arrived on earth 13,000 years ago • Found in 1993 • Contains carbonate globules formed 3.6 billion years ago Found along fractures in meteorite - not of earth origin Formed from CO2 in martian atmosphere

  39. NATS 1311 From the Cosmos to Earth • ANALYSIS OF GLOBULES: • Laser desorption mass spectrometer • Showed presence of polycyclic aromatic • hydrocarbons (PAM) unlike any on earth • These molecules contain many rings of carbon • atoms • APPEARANCE OF GLOBULES: • Transmission electron microscope images • Orange color • Flattened circular disks • Iron rich materials characteristic of fossil • remains

  40. NATS 1311 From the Cosmos to Earth • Scanning electron microscope images • Tubular shaped bodes • Dimensions - less than 100 nanometers • (1000 times smaller than the diameter of • a human hair) • Carbonate globulesare the key to biogenic activity on Mars • Globules formed in fractures of rock • Globules are younger than the rock • Globular features resemble earth microorganisms, earth biogenic carbonate structures and microfossils • Globules contain PAH's

  41. NATS 1311 From the Cosmos to Earth • CONCLUSION: • Alternative explanations exist for each globular • phenomenon taken individually • Collectively, they are evidence for primitive life on • Mars

  42. NATS 1311 From the Cosmos to Earth

  43. NATS 1311 From the Cosmos to Earth FIG. 11.16

More Related