29 episódios

Part 27: The conditions that are conducive to life, from our own solar system to the most unexpected and seemingly inhospitable places in the Universe.

These short videos were created in August 2007 by Dr. Christopher D. Impey, Professor of Astronomy at the University of Arizona, for his students. They cover a broad range of terms, concepts, and princples in astronomy and astrobiology. Dr. Impey is a University Distinguished Professor and Deputy Head of the Astonomy Department. All videos are intended solely for educational purposes and are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. The full list of collections follows below:

01. Fundamentals of Science and Astronomy
02. Ancient Astronomy and Celestial Phenomena
03. Concepts and History of Astronomy and Physics
04. Chemistry and Physics
05. Quantum Theory and Radiation
06. Optics and Quantum Theory
07. Geology and Physics
08. Solar Neighborhood and Space Exploration
09. Outer Planets and Planetary Atmospheres
10. The Solar System
11. Interplanetary Bodies
12. Formation and Nature of Planetary Systems
13. Particle Physics and the Sun
14. Stars 1
15. Stars 2
16. Stars 3
17. Galactic Mass Distribtuion and Galaxy Structure
18. Galaxies
19. Galaxies 2
20. Galaxy Interaction and Motion
21. Deep Space and High-Energy Phenomena
22. The Big Bang, Inflation, and General Cosmology
23. The Big Bang, Inflation, and General Cosmology 2
24. Chemistry and Context for Life
25. Early Earth and Life Processes
26. Life on Earth
27. Life in the Universe
28. Interstellar Travel, SETI, and the Rarity of Life
29. Prospects of Nonhuman Intelligences

27. Life in the Universe University of Arizona

    • Ciência

Part 27: The conditions that are conducive to life, from our own solar system to the most unexpected and seemingly inhospitable places in the Universe.

These short videos were created in August 2007 by Dr. Christopher D. Impey, Professor of Astronomy at the University of Arizona, for his students. They cover a broad range of terms, concepts, and princples in astronomy and astrobiology. Dr. Impey is a University Distinguished Professor and Deputy Head of the Astonomy Department. All videos are intended solely for educational purposes and are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. The full list of collections follows below:

01. Fundamentals of Science and Astronomy
02. Ancient Astronomy and Celestial Phenomena
03. Concepts and History of Astronomy and Physics
04. Chemistry and Physics
05. Quantum Theory and Radiation
06. Optics and Quantum Theory
07. Geology and Physics
08. Solar Neighborhood and Space Exploration
09. Outer Planets and Planetary Atmospheres
10. The Solar System
11. Interplanetary Bodies
12. Formation and Nature of Planetary Systems
13. Particle Physics and the Sun
14. Stars 1
15. Stars 2
16. Stars 3
17. Galactic Mass Distribtuion and Galaxy Structure
18. Galaxies
19. Galaxies 2
20. Galaxy Interaction and Motion
21. Deep Space and High-Energy Phenomena
22. The Big Bang, Inflation, and General Cosmology
23. The Big Bang, Inflation, and General Cosmology 2
24. Chemistry and Context for Life
25. Early Earth and Life Processes
26. Life on Earth
27. Life in the Universe
28. Interstellar Travel, SETI, and the Rarity of Life
29. Prospects of Nonhuman Intelligences

    • video
    Conditions on Europa

    Conditions on Europa

    Transcript: One of the most interesting places to search for life in the solar system will be Europa, one of the Galilean moons of Jupiter. Europa is about the size of Earth’s Moon, and it has a thin atmosphere where oxygen is a major constituent. Europa has a fractured water-ice surface with good evidence for liquid water oceans below the ice. The ice crust has been partially melted due to tidal heating from the planet Jupiter. The surface temperature of Europa is very cold given its distance from the Sun, minus one hundred and fifty degrees centigrade or minus two hundred and forty degrees Fahrenheit.

    • 41 s
    • video
    Evidence of Life on Europa

    Evidence of Life on Europa

    Transcript: Scientists are very uncertain what the probability is of life on or in Europa. The Galileo probe first mapped out the fissure network of surface ice that covers a liquid water layer. We only have rough estimates or models of what the thickness of the ice and water layers are. But it’s likely that the ice layer is ten kilometers thick, and the liquid layer could be as much as a hundred kilometers thick which would mean that Europa has as much liquid water on it as the sum of all the oceans of water on Earth. The surface of Europa is geologically young and is perhaps been kept active by geological activity within the small moon. The water is kept liquid, and the geological activity may be spurred by tidal heating by the large planet Jupiter which is nearby, the same mechanism that produces volcanoes on Io. The key requirement for life this distance from the Sun would be an energy source. Photosynthesis may be possible on the surface layers of the ice, but deep within the ice there’s very little energy. The best prospect is if geological activity activates deep sea vents which can foster life forms the way they do in the oceans of the Earth.

    • 1m
    • video
    Conditions on Titan

    Conditions on Titan

    Transcript: An important place to study prebiotic chemistry and perhaps to detect evidence of life itself is Titan. Titan is a major moon of Saturn, larger in size than Earth’s Moon or Pluto. Titan has a thick atmosphere of pressure one and a half bars, composed primarily of nitrogen, ninety percent, and small amounts of methane, ethane, and argon. At this distance from the Sun the temperature is low, minus a hundred and eighty degrees centigrade or minus two hundred and ninety degrees Fahrenheit. The surface is made of a mixture of rock and ice, where the ice is composed of water, methane, and ammonia. There is good evidence that Titan has liquid oceans composed primarily of ethane and methane, and it may have deep underground oceans made of ammonia and water.

    • 53 s
    • video
    Evidence of Life on Titan

    Evidence of Life on Titan

    Transcript: An important place to study prebiotic chemistry and perhaps to detect evidence of life itself is Titan. Titan is a major moon of Saturn, larger in size than Earth’s Moon or Pluto. Titan has a thick atmosphere of pressure one and a half bars, composed primarily of nitrogen, ninety percent, and small amounts of methane, ethane, and argon. At this distance from the Sun the temperature is low, minus a hundred and eighty degrees centigrade or minus two hundred and ninety degrees Fahrenheit. The surface is made of a mixture of rock and ice, where the ice is composed of water, methane, and ammonia. There is good evidence that Titan has liquid oceans composed primarily of ethane and methane, and it may have deep underground oceans made of ammonia and water.

    • 1m
    • video
    Habitable Zone

    Habitable Zone

    Transcript: The traditional habitable zone for a star is defined in the terms of water remaining as a liquid, under the strong assumption that liquid water is required for life. Remember that the habitable zone depends enormously on the luminosity of a star, and the inverse square law determines what the radiation at any distance from a star is. The inner bound of the habitable zone in our solar system is 0.8 AU. Inside that distance from the Sun, the surface temperature on a planet would be too high for liquid water to exist. The water would boil. This distance is midway between the orbits of Venus and the Earth. The outer bound of the habitable zone is 1.7 astronomical units. This is slightly outside the orbit of Mars at 1.5 AU. Beyond this distance, water would be frozen. But these ranges can be modified because in inner regions atmospheres of certain compositions can act to shelter the water, and at distances beyond the edge of the formal habitable zone, greenhouse gases could possibly raise the temperature beyond that of energy incident from the Sun, allowing liquid water to exist.

    • 1m
    • video
    Extreme Habitable Zone

    Extreme Habitable Zone

    Transcript: The traditionally defined habitable zone, the distance from the Sun within which liquid water can exist, extends from 0.8 to 1.7 AU. This range encompasses the Earth and Mars only within the solar system. However, our knowledge of the extreme possibilities of life surviving on Earth, extremophiles, and our detailed knowledge of environments elsewhere in the solar system leads us to believe that the true habitable zone could be much larger. For example, the conditions on Titan and Europa are possible to allow them to have life, and yet they are much further from the Sun. Titan is a moon of Saturn at ten astronomical units, and Europa is a moon of Jupiter at about five astronomical units. So the habitable zone could extend much further to the regime of giant planets and their moons. The key here is the energy source provided by tidal heating. Moons in orbit around large planets at close distances can have an extra heat source due to tidal heating which makes up for the shortfall in solar radiation. Thus the most generous bound on a habitable zone could include a significant number of objects in planetary systems around other stars.

    • 1m

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