Astronomy 141 - Life in the Universe - Autumn Quarter 2009

By Richard PoggeScience Education Courses Natural Sciences Astronomy

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

October 30, 2009 Lecture 26: The Deserts of Mars
For many, the most likely place in the Solar System to search for life
beyond the Earth is Mars. This lecture describes the properties of
Mars, a desert world with a thin, dry, cold carbon dioxide atmosphere.
I will review evidence that has begun to point unequivocally to the
conclusion that Mars had flowing and standing liquid water on its
surface in the past, perhaps during the first billion years or so.
If Mars had a warm, wet past, did life also get a start there?
Recorded live on 2009 Oct 30 in Room 1005 Smith Laboratory on the
Columbus campus of The Ohio State University.
48 min
October 29, 2009 Lecture 25: The Requirements for Life in the Solar System
Having completed our tour of the Solar System, we now turn to a
discussion of the requirements for life, and where those requirements
might be satisfied elsewhere in the Solar System. Some - energy,
complex chemistry, and liquid water - seem obvious, but they are not the
only possibilities or considerations. At the end, we will have a short
list of possible places to look, some expected, others surprising.
Recorded live on 2009 Oct 29 in Room 1005 Smith Laboratory on the
Columbus campus of The Ohio State University.
48 min
October 28, 2009 Lecture 24: The Jovian Planets
We turn our attention to the Giant Planets of the outer Solar System:
the gas giants Jupiter and Saturn, and the ice giants Uranus and Neptune.
We will review their structure and properties, and then examine their
systems of moons, with special attention to the giant moons. While the
Jovian planets themselves seem unlikely places to hunt for life in our
Solar System, a few of their largest moons may be more promising than
appears at first sight. We'll explore this further in subsequent lectures
in this unit. Recorded live on 2009 Oct 28 in Room 1005 Smith Laboratory
on the Columbus campus of The Ohio State University.
48 min
October 27, 2009 Lecture 23: Terrestrial Worlds in Comparison
We follow our tour of our Solar System with an in-depth comparison of
the Terrestrial Planets. In particular, we want to contrast and compare
their geological and atmospheric histories. This will inform our
inquiry into whether or not we expect to find life on these worlds.
Recorded live on 2009 Oct 27 in Room 1005 Smith Laboratory on the
Columbus campus of The Ohio State University.
47 min
October 26, 2009 Lecture 22: The Family of the Sun
This first lecture of Unit 4 - Life in the Solar System - is a quick
tour of our Solar System reviewing the planets, dwarf planets, moons,
and small bodies that make up our celestial home. This lecture will
introduce many of the places we will be considering in detail over the
next two weeks, and which we'll find around other stars. Recorded live
on 2009 Oct 26 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.
47 min
October 22, 2009 Lecture 21: Impacts and Extinction
We end our exploration of life on the Earth with a look at death in the
fossil record. This lecture looks at the role asteroidal impacts have
played in the history of the Earth, and their possible role in mass
extinction events in the fossil record. We will discuss near-earth
asteroids, historical impacts, and the K-T event in which a massive
asteroid impact caused a mass extinction of species that included all
non-avian dinosaurs among its victims, opening up the biosphere to the
dominance of mammals. We'll look at other mass extinctions during the
past 500Myr, and talk about whether extinction-class impacts are in our
future. Recorded live on 2009 Oct 22 in Room 1005 Smith Laboratory on
the Columbus campus of The Ohio State University.
47 min
October 21, 2009 Lecture 20: The History of Life on Earth
In this lecture we step back and look at the history of life on Earth
from the first signs of life at start of the Archaean Eon 3.5 billion
years ago to just up to the present day. We will review the appearance
of photosynthesis and the rise of oxygen in the atmosphere in the
Proterozoic, the appearance of the first eukaryotes and sexual
reproduction, and the Cambrian explosion of plant and animal species at
the start of the Phanerozoic Eon, and briefly review the changes in life
to the present day from the Cambrian Explosion to the colonization of
land by plants and then animals. Most of the lecture will be where most
of the time was spent, in the early, microbiological Earth. Recorded
live on 2009 Oct 21 in Room 1005 Smith Laboratory on the Columbus campus
of The Ohio State University.
48 min
October 20, 2009 Lecture 19: The Origin of Life on Earth
How did life arise from non-life? Frankly, we don't know, but current
experimental work is aimed at trying to understand how it might work in
biochemical terms. This lecture sets out the problem of "abiogenesis",
and describes our current thinking about the likely origins of life on
Earth. We will review the classic Miller-Urey experiment, and look at
its insights and limitations, discuss meteoritic sources of amino acids,
and the basic requirements needed for protolife. I will then describe
in outline two scenarios that are active areas of origins research: the
RNA World model and the Metabolism First model. Finally, I will very
briefly mention Exogenesis and Panspermia, which don't really address
the problem of abiogenesis so much as move it elsewhere. Recorded live
on 2009 Oct 20 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.
47 min
October 19, 2009 Lecture 18: The First Living Things on Earth
What are the first recognizable forms of life that we find in the
geological record? How far back can we go in geological time and still
find life? This lecture reviews three lines of evidence that have
emerged in recent years to suggest that life may have emerged very early
on the young Earth, perhaps within a few hundred million years of the
end of the epoch of heavy bombardment. I will describe fossil
stromatolites, microfossils, and carbon isotope data that are used to
explore these questions. Recorded live on 2009 Oct 19 in Room 1005
Smith Laboratory on the Columbus campus of The Ohio State University.
47 min
October 16, 2009 Lecture 17: Life on the Edge
Extremophiles are organisms that are adapted to survive in extreme
environments. This lecture describes the challenges that
extremes of heat, cold, acidity, salinity, and radiation pose to
organisms, and show examples of how evolution has nonetheless allowed
some organisms to adapt to not just survive but thrive in such extreme
conditions. Finally, we will explore the possible limits of life on
Earth, and find that while you can make things pretty extreme and still
have organisms adapt, you reach the limit if there is no water. Rather
than being oddballs, these organisms give us important insights into the
origins of life on Earth, and widens the possibilities for life on other
worlds. Recorded live on 2009 Oct 16 in Room 1005 Smith Laboratory on
the Columbus campus of The Ohio State University.
47 min