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Astronomy 141 - Life in the Universe - Autumn Quarter 2009

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Rank #65 in Courses category

Education
Courses
Science
Natural Sciences
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Astronomy 141, Life in the Universe, is a one-quarter introduction toAstrobiology for non-science majors taught at The Ohio State University.This podcast presents audio recordings of Professor Richard Pogge'slectures from his Autumn Quarter 2009 class. All of the lectures were recorded live in 1005 Smith Laboratory on the OSU Main Campus in Columbus, Ohio.

Read more

Astronomy 141, Life in the Universe, is a one-quarter introduction toAstrobiology for non-science majors taught at The Ohio State University.This podcast presents audio recordings of Professor Richard Pogge'slectures from his Autumn Quarter 2009 class. All of the lectures were recorded live in 1005 Smith Laboratory on the OSU Main Campus in Columbus, Ohio.

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Astronomy 161 & 162

By CPGguy - Oct 03 2017
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Excellent, educational and entertaining!

Thank you

By Aaronjw84 - Nov 15 2012
Read more
Thanks for these podcasts. Been listening to them for 9hrs straight now :D

iTunes Ratings

104 Ratings
Average Ratings
87
8
4
1
4

Astronomy 161 & 162

By CPGguy - Oct 03 2017
Read more
Excellent, educational and entertaining!

Thank you

By Aaronjw84 - Nov 15 2012
Read more
Thanks for these podcasts. Been listening to them for 9hrs straight now :D

Listen to:

Cover image of Astronomy 141 - Life in the Universe - Autumn Quarter 2009

Astronomy 141 - Life in the Universe - Autumn Quarter 2009

Updated 3 days ago

Read more

Astronomy 141, Life in the Universe, is a one-quarter introduction toAstrobiology for non-science majors taught at The Ohio State University.This podcast presents audio recordings of Professor Richard Pogge'slectures from his Autumn Quarter 2009 class. All of the lectures were recorded live in 1005 Smith Laboratory on the OSU Main Campus in Columbus, Ohio.

Lecture 41: Interstellar Travel and Colonization

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If we ever detect life elsewhere, how will we go visit? This lecture
considers the challenges of interstellar travel and colonization. The
problem is one of basic physics (the enormous energy requirements of
star flight) coupled with the vast, irreducible distances between the
stars. I will describe various starship concepts that use reasonable
extrapolations of current technologies (nuclear propulsion and solar
sails), ignoring for our discussions science-fiction exotica like
faster-than-light drives and wormholes. My interest is in the
scientific aspects of the problem, not an exploration of speculative
fiction. I then turn to interstellar colonization, and how even
a relatively modest star-flight capability might allow a determined
civilization to colonize the entire galaxy very rapidly. This has
implications for how we might interpret the results of Drake Equation
type arguments about the frequency of intelligent life in the Galaxy,
and leads to the Fermi Paradox that will be the topic of the next
lecture. Recorded live on 2009 Nov 25 in Room 1005 Smith Laboratory on
the Columbus campus of The Ohio State University.

Nov 25 2009

45mins

Play

Lecture 19: The Origin of Life on Earth

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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.

Oct 20 2009

46mins

Play

Lecture 40: SETI - The Search for Extra-Terrestrial Intelligence

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Is anybody out there? This lecture reviews the ideas behind SETI, the
Search for Extra-Terrestrial Intelligence, an effort to find other
intelligent communicating civilizations by tuning in on their radio or
other electromagnetic communications. I will discuss the basic
approaches being taken by various SETI efforts, and what we expect to
find. In addition to listening, we have also been broadcasting,
intentionally or otherwise, messages into space, and we have sent
physical artifacts with descriptions of our home on robotic spacecraft
headed out of our solar system into interstellar space. Recorded live
on 2009 Nov 24 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.

Nov 24 2009

46mins

Play

Lecture 2: Astronomical Numbers

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An introduction and review of the basic notation and physical units we will be
using throughout this course. In particular, we will be using the
Metric (SI) system for lengths, masses, times, and temperatures, and
special astronomical units for distances (AU and Light Years) and masses
(Earth Masses and Solar Masses) appropriate when discussing
interplanetary and interstellar scales. Recorded live on 2009 Sep 24 in
Room 1005 Smith Laboratory on the Columbus campus of The Ohio State
University.

Sep 24 2009

43mins

Play

Lecture 3: Imagining Other Worlds

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What is the cultural history of our imaginings of other worlds and their
possible inhabitants? I will draw examples from history, philosophy,
literature, cinema, and popular culture. In the end,
our imaginings about other worlds inform us more about ourselves, our
hopes and our fears, than about extraterrestrial life. The scientific
inquiry we are undertaking must therefore approach the problem from a
different direction. Recorded live on 2009 Sep 25 in Room 1005 Smith
Laboratory on the Columbus campus of The Ohio State University.

Sep 25 2009

40mins

Play

Lecture 39: The Drake Equation

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How many intelligent, communicating civilizations live in our Galaxy?
We have no idea. One way to approach the question and come up with
quasi-quantitative estimates is the Drake Equation, first introduced by
radio astronomy Frank Drake in the 1960s. I will use the Drake equation
as an illustration of the issues related to the question of
extraterrestrial intelligence, and to set the stage for future lectures
on the likelihood of finding other intelligences in our Universe.
Recorded live on 2009 Nov 23 in Room 1005 Smith Laboratory on the
Columbus campus of The Ohio State University.

Nov 23 2009

45mins

Play

Lecture 20: The History of Life on Earth

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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.

Oct 21 2009

47mins

Play

Lecture 21: Impacts and Extinction

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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.

Oct 22 2009

46mins

Play

Lecture 8: The Cosmological Revolution - The Depths of Space and Time

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Cosmology is the study of the entire Universe as a physical system. The
past century has witnessed a revolution in cosmological thought that has
revealed the vastness of space and the depths of cosmic time, a revolution
that is still playing out in the present day. The lecture will review the
Earth's place in the Universe, the age of the Universe as reckoned by the time
since the Big Bang, and the origin of the elements. We will return to
many of these topics later in the course, but this presents the big
picture. Recorded live on 2009 Oct 2 in Room 1005 Smith Laboratory on
the Columbus campus of The Ohio State University.

Oct 02 2009

46mins

Play

Lecture 28: The Galilean Moons of Jupiter

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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.

Nov 03 2009

44mins

Play

Lecture 27: Is There Life on Mars?

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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.

Nov 02 2009

47mins

Play

Lecture 4: The Copernican Revolution

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Modern science was borne of an effort over many centuries to understand
the motions of celestial bodies. The Copernican Revolution of the 16th
and 17th centuries was the crucial moment in history when we finally
understood the nature of celestial motions, and opened the door to the
modern world. This lecture reviews the problem of celestial motions,
the two competing models for explaining them, and the final revolution
in thought starting with Copernicus and ending with Newton. Mid-lecture
my classroom AV system lost power, and the recovery slowed things down a
bit. These are recorded live, after all. This lecture was conducted on
2009 Sep 28 in Room 1005 Smith Laboratory on the Columbus campus of The
Ohio State University.

Sep 28 2009

43mins

Play

Lecture 37: Strange New Worlds

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What are the properties of the 400+ exoplanets we have discovered so
far? This lecture reviews the properties of exoplanets, and finds a
couple of surprises: Jupiter-mass planets orbiting close to their parent
stars, and Jupiter-mass planets in very elliptical orbits. Both seem to
require some mechanism for migration: strong gravitational interactions
with either the protoplanetary disk or other giant planets to cause the
planets to move inward from their birth places beyond the "Ice Line".
We will then briefly discuss why we are seeing systems very different
from our own, mostly we think a selection effect due to our search
methods to date. Microlensing, however, is more sensitive to systems
like ours, and is starting to find them. Earths, however, remain
elusive so far, but the hunt is on. Recorded live on 2009 Nov 18 in
Room 1005 Smith Laboratory on the Columbus campus of The Ohio State
University.

Nov 18 2009

46mins

Play

Lecture 38: The Pale Blue Dot - Seeking Other Earths

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Are there other Earths out there? Do they have life on them? This
lecture looks at the search for ExoEarths - Earth-sized planets in the
habitable zones of their parent stars, and what we might learn from
measuring them. The ultimate goal of all planet searches is to find
other Earth's, what the late Carl Sagan so poetically called
the "pale blue dot" as seen from the depths of space. This lecture
discusses what we might learn about such planets from studies of our own
Earth, spectroscopic biomarkers that might reveal life, and variability
studies that might give us insight into surface features (continents
and oceans) and weather (clouds and even climate). Recorded live on
2009 Nov 19 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.

Nov 19 2009

44mins

Play

Lecture 11: The History of the Earth

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How have we pieced together the geological history of the Earth?
This lecture reviews the different types of rocks and the cycle
of transformation between them, with particular emphasis on stratigraphy.
I will outline the 4 major Eons in Earth's history, and focus on the
earliest Hadean Eon which proceeded from the formation of the Earth to
the end of the epoch of Heavy Bombardment. The Hadean Eon saw the formation
of the primordial atmosphere of the Earth and the formation of the Oceans.
Recorded live on 2009 Oct 7 in Room 1005 Smith Laboratory on the Columbus
campus of The Ohio State University.

Oct 07 2009

42mins

Play

Lecture 9: Inside the Earth

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What is the interior structure of the Earth and how does it drive the
Earth's magnetic and geologic activity? We will review our current
knowledge of the interior of the Earth, how we measure it using
Seismology, the origins of the Earth's magnetic field, and discuss the
workings of plate tectonics. the Earth is a dynamic, geologically
active world, which has interesting implications later for understanding
the past and future history of life on Earth. Recorded live on 2009 Oct
5 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State
University.

Oct 05 2009

42mins

Play

Lecture 12: Climate Regulation and Climate Change

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What are the main mechanisms of climate regulation and climate
change that have operated through Earth's history? The Earth's
climate is regulated by a Carbon Dioxide thermostat that is the
interaction between the Greenhouse Effect and the CO2 Cycle. I describe
the CO2 cycle and its role in regulating global temperature. I will
then discuss other influences on climate, and periods of glaciation (ice
ages) in the recent and distant past, including the possible Snowball
Earth events in the early and late Proterozoic Eon. Recorded live on
2009 Oct 8 in Room 1005 Smith Laboratory on the Columbus campus of The
Ohio State University.

Oct 08 2009

45mins

Play

Lecture 18: The First Living Things on Earth

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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.

Oct 19 2009

46mins

Play

Lecture 26: The Deserts of Mars

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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.

Oct 30 2009

47mins

Play

Lecture 33: The Deaths of Stars

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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.

Nov 12 2009

47mins

Play

Lecture 46: This View of Life (Course Finale)

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Course finale and summary. We look back over where we've been the last
eleven weeks, and bring together all of the main themes of this course
on Life in the Universe. Recorded live on 2009 Dec 4 in Room 1005 Smith
Laboratory on the Columbus campus of The Ohio State University.

Dec 04 2009

41mins

Play

Lecture 45: The Future of Life in the Universe

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How will life, the Universe, and everything end? This lecture looks at
the evolution of our expanding Universe to project the prospects for
life into the distant cosmological future. Recent observations show
that we live in an infinite, accelerating universe. I will trace the
evolution of the universe from the current age of stars into the future.
The final state of the Universe will be cold, dark, and disordered, and
ultimately inhospitable to life as we understand it or perhaps can
imagine it. Recorded live on 2009 Dec 3 in Room 1005 Smith Laboratory
on the Columbus campus of The Ohio State University.

Dec 03 2009

44mins

Play

Lecture 44: The Future of Life in the Solar System

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What is the future of life on Earth and in our Solar System? The Sun is
the source of energy for life on the Earth, but it will not shine
forever. This lecture looks at the impact of the various stages of the
evolution of the Sun on the habitability of the Solar System, with
particular emphasis on the continued habitability of the Earth. I will
refer to state-of-the-art computer models of the Sun to get is
properties at various stages in its past and future life. NOTE: Due to
a recorder malfunction this lecture was re-recorded later in the day on
2009 Dec 2, rather than being live from the class room in Smith
Laboratory. As such, it is about 10 minutes longer than usual (my
pacing is off when not in front of class).

Dec 02 2009

55mins

Play

Lecture 43: Extraterrestrial Life

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What does extraterrestrial life look like? This lecture explores
current thinking about what extraterrestrial life might be like not by
guessing their appearances, but instead applying lessons learned from
our growing understanding of how evolution and biochemistry work on
Earth. I will discuss Universal versus Parochial characteristics,
Convergent Evolution, Radical Diversity, and other ideas from
evolutionary biology that might inform how life might emerge on other
worlds. We will then look at alternatives to carbon biochemistry,
specifically the possibility of silicon-based life, and alternatives to
liquid water as a solvent medium for biochemistry, specifically the
possible role of Ammonia. Finally I will give one example of a highly
speculative idea about life without chemistry. In the end, the outcome
of such studies may not be to tell us much about extraterrestrials as to
help focus questions on how we ourselves arose. Recorded live on 2009
Dec 1 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio
State University.

Dec 01 2009

45mins

Play

Lecture 42: The Fermi Paradox

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So, Where is Everybody? Interstellar colonization, in principle, is an
exponential growth process that would fill the galaxy in a few million
years even with a very modest star flight capability. This is a small
fraction of the lifetime of the Milky Way Galaxy, so the Galaxy should
be teaming with life. But, we so far have no compelling evidence of
extraterrestrial visitations, alien artifacts, or any other evidences
that the Galaxy is populated. Physicist and Nobel Laureate Enrico
Fermi's apparent paradox and some of the proposed resolutions are the
topic of this lecture. I will review the Fermi Paradox and describe the
most common possible resolutions. The Fermi Paradox is useful in
helping to frame the question of extraterrestrial life, even if we so
far have no answers. At the end I only touch on the Rare Earth
Hypothesis, but this is a very nuanced question which requires a whole
other lecture to explore that I have not had time to fully prepare for
during this busy quarter. Recorded live on 2009 Nov 30 in Room 1005
Smith Laboratory on the Columbus campus of The Ohio State University.

Nov 30 2009

44mins

Play

Lecture 41: Interstellar Travel and Colonization

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If we ever detect life elsewhere, how will we go visit? This lecture
considers the challenges of interstellar travel and colonization. The
problem is one of basic physics (the enormous energy requirements of
star flight) coupled with the vast, irreducible distances between the
stars. I will describe various starship concepts that use reasonable
extrapolations of current technologies (nuclear propulsion and solar
sails), ignoring for our discussions science-fiction exotica like
faster-than-light drives and wormholes. My interest is in the
scientific aspects of the problem, not an exploration of speculative
fiction. I then turn to interstellar colonization, and how even
a relatively modest star-flight capability might allow a determined
civilization to colonize the entire galaxy very rapidly. This has
implications for how we might interpret the results of Drake Equation
type arguments about the frequency of intelligent life in the Galaxy,
and leads to the Fermi Paradox that will be the topic of the next
lecture. Recorded live on 2009 Nov 25 in Room 1005 Smith Laboratory on
the Columbus campus of The Ohio State University.

Nov 25 2009

45mins

Play

Lecture 40: SETI - The Search for Extra-Terrestrial Intelligence

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Is anybody out there? This lecture reviews the ideas behind SETI, the
Search for Extra-Terrestrial Intelligence, an effort to find other
intelligent communicating civilizations by tuning in on their radio or
other electromagnetic communications. I will discuss the basic
approaches being taken by various SETI efforts, and what we expect to
find. In addition to listening, we have also been broadcasting,
intentionally or otherwise, messages into space, and we have sent
physical artifacts with descriptions of our home on robotic spacecraft
headed out of our solar system into interstellar space. Recorded live
on 2009 Nov 24 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.

Nov 24 2009

46mins

Play

Lecture 39: The Drake Equation

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How many intelligent, communicating civilizations live in our Galaxy?
We have no idea. One way to approach the question and come up with
quasi-quantitative estimates is the Drake Equation, first introduced by
radio astronomy Frank Drake in the 1960s. I will use the Drake equation
as an illustration of the issues related to the question of
extraterrestrial intelligence, and to set the stage for future lectures
on the likelihood of finding other intelligences in our Universe.
Recorded live on 2009 Nov 23 in Room 1005 Smith Laboratory on the
Columbus campus of The Ohio State University.

Nov 23 2009

45mins

Play

Lecture 38: The Pale Blue Dot - Seeking Other Earths

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Are there other Earths out there? Do they have life on them? This
lecture looks at the search for ExoEarths - Earth-sized planets in the
habitable zones of their parent stars, and what we might learn from
measuring them. The ultimate goal of all planet searches is to find
other Earth's, what the late Carl Sagan so poetically called
the "pale blue dot" as seen from the depths of space. This lecture
discusses what we might learn about such planets from studies of our own
Earth, spectroscopic biomarkers that might reveal life, and variability
studies that might give us insight into surface features (continents
and oceans) and weather (clouds and even climate). Recorded live on
2009 Nov 19 in Room 1005 Smith Laboratory on the Columbus campus of
The Ohio State University.

Nov 19 2009

44mins

Play

Lecture 37: Strange New Worlds

Podcast cover
Read more
What are the properties of the 400+ exoplanets we have discovered so
far? This lecture reviews the properties of exoplanets, and finds a
couple of surprises: Jupiter-mass planets orbiting close to their parent
stars, and Jupiter-mass planets in very elliptical orbits. Both seem to
require some mechanism for migration: strong gravitational interactions
with either the protoplanetary disk or other giant planets to cause the
planets to move inward from their birth places beyond the "Ice Line".
We will then briefly discuss why we are seeing systems very different
from our own, mostly we think a selection effect due to our search
methods to date. Microlensing, however, is more sensitive to systems
like ours, and is starting to find them. Earths, however, remain
elusive so far, but the hunt is on. Recorded live on 2009 Nov 18 in
Room 1005 Smith Laboratory on the Columbus campus of The Ohio State
University.

Nov 18 2009

46mins

Play

Lecture 36: Exoplanets - Planets Around Other Stars

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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.

Nov 17 2009

47mins

Play

Lecture 35: The Solar Neighborhood

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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.

Nov 16 2009

46mins

Play

Lecture 34: Habitable Zones around Stars

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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.

Nov 13 2009

47mins

Play

Lecture 33: The Deaths of Stars

Podcast cover
Read more
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.

Nov 12 2009

47mins

Play

Lecture 32: The Lives of Stars

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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.

Nov 10 2009

46mins

Play

Lecture 31: The Properties of Stars

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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.

Nov 09 2009

46mins

Play

Lecture 30: Goldilocks and the Three Planets

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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.

Nov 05 2009

46mins

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Lecture 29: The Children of Saturn

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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.

Nov 04 2009

46mins

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Lecture 28: The Galilean Moons of Jupiter

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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.

Nov 03 2009

44mins

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Lecture 27: Is There Life on Mars?

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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.

Nov 02 2009

47mins

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