Astronomy 141 - Life in the Universe - Autumn Quarter 2009

Astronomy 141 - Life in the Universe - Autumn Quarter 2009

By Richard PoggeScienceEducationCoursesNatural SciencesAstronomy
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Astronomy 141 - Life in the Universe - Autumn Quarter 2009 episodes

  • Lecture 36: Exoplanets - Planets Around Other Stars
    Are there planets around other stars? This lecture reviews the methods
    used to hunt for exoplanets and the results thus far. I will describe
    direct imaging methods, indirect methods relying on the gravitational
    influence of the planet on its parent star, planetary transits in which
    a planet blocks part of its parent star's light, and gravitational
    microlensing. There has been an explosion in our knowledge of planets
    around other stars, from little or nothing in the early 1990s to more
    than 400 planets around some 340-odd stars as of today. Recorded live
    on 2009 Nov 17 in Room 1005 Smith Laboratory on the Columbus campus of
    The Ohio State University.
    48 min
  • Lecture 35: The Solar Neighborhood
    What stars are near the Sun? Now that we have some idea of what we are
    looking for - rocky planets in the habitable zones of low-mass
    main-sequence stars - what are the prospects near the Sun? This lecture
    examines the hunting ground for planets, the nearby stars that make up
    the Solar Neighborhood. I will describe our nearest neighbor, the
    Proxima Centauri/Alpha Centauri triple system, and then look at the
    properties of our nearest stellar neighbors. What we will find is that
    G-type stars like the Sun are uncommon, only about 7% of all nearby
    main-sequence stars. Red dwarfs, on the other hand, are very common,
    about 75%. To find Sun-like main sequence stars, we will have to extend
    our search to larger distances into our Milky Way galaxy proper.
    Recorded live on 2009 Nov 16 in Room 1005 Smith Laboratory on the
    Columbus campus of The Ohio State University.
    47 min
  • Lecture 34: Habitable Zones around Stars
    Which stars are the most hospitable for life? This lecture examines the
    factors affecting the habitability of stars, with a goal of
    understanding where we should search for life-bearing planets. We will
    do this by generalizing the idea of a Habitable Zone developed for the
    Sun back in Lecture 30. In this context, we find that the best places
    to search for life would be rocky planets in the habitable zones of
    low-mass main-sequence stars. There are a number of caveats we will
    discuss - tidal locking, stellar flares, and UV radiation - and
    limitations to the approach, but it seems to be a good place to start
    our search. Recorded live on 2009 Nov 13 in Room 1005 Smith Laboratory
    on the Columbus campus of The Ohio State University.
    48 min
  • Lecture 33: The Deaths of Stars
    What happens to a star when it runs out of hydrogen in its core? This
    lecture describes the post main-sequence evolution of stars. What
    happens depends on the star's mass. Low mass stars swell up into Red
    Giants, and eventually shed their envelopes and end their lives as white
    dwarf stars. High mass stars become Red Supergiants, and if large
    enough, end their lives in a spectacular supernova explosion that leaves
    behind a neutron star or black hole. The explosion itself creates
    massive quantities of heavy elements, which then seed interstellar space
    with metals to be incorporated into subsequent generations of stars.
    Recorded live on 2009 Nov 12 in Room 1005 Smith Laboratory on the
    Columbus campus of The Ohio State University.
    48 min
  • Lecture 32: The Lives of Stars
    Why do stars shine? How long do they shine? This lecture describes the
    physics of stars on the main sequence, describes the mass-luminosity
    relation of main sequence stars, introduces nuclear fusion power and the
    nuclear fusion lifetimes of stars. From this we gain an important
    insight into one of the criteria we might apply to the search for life
    around other stars: we want planets around low-mass main sequence stars
    that can shine more or less steadily for more that 500 Myr to 1 billion
    years - maybe longer if our goal is to find intelligent life. Recorded
    live on 2009 Nov 10 in Room 1005 Smith Laboratory on the Columbus campus
    of The Ohio State University.
    47 min
  • Lecture 31: The Properties of Stars
    What are the observed properties of stars? This lecture is a quick
    review of the basic observational properties of stars, introducing
    luminosity, spectral classification, the luminosity-radius-temperature
    relation, and the Hertzsprung-Russell (H-R) diagram. This sets up the
    empirical basis of subsequent lectures on the lives and deaths of stars.
    Recorded live on 2009 Nov 9 in Room 1005 Smith Laboratory on the
    Columbus campus of The Ohio State University.
    47 min
  • Lecture 30: Goldilocks and the Three Planets
    Why is the Earth habitable today but Venus and Mars not? This lecture
    explores the question of planetary habitability from the perspective of
    the stability of liquid water on the surface of planetary bodies. We
    will see how the amount of sunlight and the greenhouse effect in the
    atmosphere combine to create a classic Goldilocks problem: whether or
    not a planetary surface has stable liquid water is a question of not
    being too hot or too cold. This defines the Habitable Zone for the
    present-day Sun. However, the size of a planet also plays a role, and
    we will expand the concept of habitability to include the type of
    atmosphere a planetary body can or cannot retain. Finally, because the
    Sun changes brightness slowly over its lifetime, the location of the
    habitable zone is time-dependent. We will define the Continuous
    Habitable Zone, and discuss implications, and limitations, of the idea
    of habitable zones, looking forward expanding our search for life to
    worlds around other stars. Recorded live on 2009 Nov 5 in Room 1005
    Smith Laboratory on the Columbus campus of The Ohio State University.
    47 min
  • Lecture 29: The Children of Saturn
    Among the 61 known moons of Saturn, two stand out: Enceladus and Titan.
    Giant Titan is the only moon in our Solar System with a substantial
    atmosphere, composed of nitrogen and methane, dense enough to maintain a
    weather cycle with methane analogous to the water cycle on Earth, even
    including great lakes of liquid methane and ethane at the poles.
    Enceladus has fountains of water vapor and ice particles that coat its
    surface in fresh ices, and indicates the presence of liquid water
    beneath its icy surface. Is this just pockets of tidal-heated water, or
    hints of a deep global liquid water ocean. I will describe new results
    on these two children of Saturn, and the possibilities they have for
    finding life, or life-like conditions, elsewhere in our Solar System.
    Recorded live on 2009 Nov 4 in Room 1005 Smith Laboratory on the
    Columbus campus of The Ohio State University.
    47 min
  • Lecture 28: The Galilean Moons of Jupiter
    The four large Galilean Moons of Jupiter seem unlikely places to look
    for life; at first glance they should be cold, dead, icy worlds.
    Instead we find tremendous geological diversity, and two big surprises:
    volcanically-active Io, and icy Europa. Io is the most volcanically
    active world in the Solar System, heated by tides from Jupiter. Europa
    is even more surprising: its icy surface is young, with few impact
    craters and extensive signs of recent repaving by liquid water. Even
    more surprising is the distinct possibility that underneath Europa's ice
    is a deep liquid water ocean, heated by tides from Jupiter. We will
    review the evidence for Europa's liquid sub-ice ocean and look at its
    potential as an abode of life. If there is life to be found anywhere in
    the Solar System beyond Earth, beneath the ice of Europa may be the best
    place to look. Recorded live on 2009 Nov 3 in Room 1005 Smith
    Laboratory on the Columbus campus of The Ohio State University.
    45 min
  • Lecture 27: Is There Life on Mars?
    Is there life on Mars? We begin with a brief historical survey of the
    idea of inhabitable Mars, from Herschel to Lowell, and look at how the
    idea of Mars and Martians is deeply embedded in the popular culture.
    We then turn to spacecraft explorations of Mars, and how they have changed
    our view of the Red planet. We will discuss the on-going search of Martian
    life, past and present, particularly the Viking 1 and 2 experiments, the
    Allan Hills Meteorite controversy, Mars Methane, and recent important
    results from the Phoenix lander. We'll end by briefly noting future
    directions in Mars exploration.
    Recorded live on 2009 Nov 2 in Room 1005 Smith
    Laboratory on the Columbus campus of The Ohio State University.
    48 min

About Astronomy 141 - Life in the Universe - Autumn Quarter 2009

From the publisher's feed

Astronomy 141, Life in the Universe, is a one-quarter introduction to

Best of Astronomy 141 - Life in the Universe - Autumn Quarter 2009

Ranked by our users in the last 21 days

  1. Number 1: Lecture 45: The Future of Life in the Universe
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  2. Number 2: Lecture 44: The Future of Life in the Solar System
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  3. Number 3: Lecture 12: Climate Regulation and Climate Change
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