Are there other Earths out there?  Do they have life on them?  Thislecture looks at the search for ExoEarths - Earth-sized planets in thehabitable zones of their parent stars, and what we might learn frommeasuring them.  The ultimate goal of all planet searches is to findother Earth's, what the late Carl Sagan so poetically calledthe "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.

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.

Lecture 38: The Pale Blue Dot - Seeking Other Earths

This first lecture of Unit 4 - Life in the Solar System - is a quicktour of our Solar System reviewing the planets, dwarf planets, moons,and small bodies that make up our celestial home.  This lecture willintroduce many of the places we will be considering in detail over thenext two weeks, and which we'll find around other stars.  Recorded liveon 2009 Oct 26 in Room 1005 Smith Laboratory on the Columbus campus ofThe Ohio State University.

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.

Lecture 22: The Family of the Sun

For many, the most likely place in the Solar System to search for lifebeyond the Earth is Mars.  This lecture describes the properties ofMars, a desert world with a thin, dry, cold carbon dioxide atmosphere.I will review evidence that has begun to point unequivocally to theconclusion that Mars had flowing and standing liquid water on itssurface 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 theColumbus campus of The Ohio State University.

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.

Lecture 26: The Deserts of Mars

What are the properties of the 400+ exoplanets we have discovered sofar?  This lecture reviews the properties of exoplanets, and finds acouple of surprises: Jupiter-mass planets orbiting close to their parentstars, and Jupiter-mass planets in very elliptical orbits.  Both seem torequire some mechanism for migration: strong gravitational interactionswith either the protoplanetary disk or other giant planets to cause theplanets to move inward from their birth places beyond the "Ice Line".We will then briefly discuss why we are seeing systems very differentfrom our own, mostly we think a selection effect due to our searchmethods to date.  Microlensing, however, is more sensitive to systemslike ours, and is starting to find them.  Earths, however, remainelusive so far, but the hunt is on.  Recorded live on 2009 Nov 18 inRoom 1005 Smith Laboratory on the Columbus campus of The Ohio StateUniversity.

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.

Lecture 37: Strange New Worlds

This lecture was to be about the Earth's atmosphere, its composition andstructure, the greenhouse effect, and the primordial atmosphere, butabout 2 seconds into the lecture, unbeknownst to me, the batterycompartment on my digital voice recorder came open in my pocket.  At theend of lecture, I took it out of my pocket to turn it off and thebattery didn't come with it.  Oops! Fail.  My apologies, I'll put insome work to prevent a recurrence in future lectures.  Recorded live on2009 Oct 6 in Room 1005 Smith Laboratory on the Columbus campus of TheOhio State University.

This lecture was to be about the Earth's atmosphere, its composition and structure, the greenhouse effect, and the primordial atmosphere, but about 2 seconds into the lecture, unbeknownst to me, the battery compartment on my digital voice recorder came open in my pocket. At the end of lecture, I took it out of my pocket to turn it off and the battery didn't come with it. Oops! Fail. My apologies, I'll put in some work to prevent a recurrence in future lectures. Recorded live on 2009 Oct 6 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.

Lecture 10: The Earth's Atmosphere Erratum

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 substantialatmosphere, composed of nitrogen and methane, dense enough to maintain aweather cycle with methane analogous to the water cycle on Earth, evenincluding great lakes of liquid methane and ethane at the poles.Enceladus has fountains of water vapor and ice particles that coat itssurface in fresh ices, and indicates the presence of liquid waterbeneath its icy surface.  Is this just pockets of tidal-heated water, orhints of a deep global liquid water ocean.  I will describe new resultson these two children of Saturn, and the possibilities they have forfinding life, or life-like conditions, elsewhere in our Solar System.Recorded live on 2009 Nov 4 in Room 1005 Smith Laboratory on theColumbus campus of The Ohio State University.

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.

Lecture 29: The Children of Saturn

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.

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.

Lecture 24: The Jovian Planets

So, Where is Everybody?  Interstellar colonization, in principle, is anexponential growth process that would fill the galaxy in a few millionyears even with a very modest star flight capability.  This is a smallfraction of the lifetime of the Milky Way Galaxy, so the Galaxy shouldbe teaming with life.  But, we so far have no compelling evidence ofextraterrestrial visitations, alien artifacts, or any other evidencesthat the Galaxy is populated.  Physicist and Nobel Laureate EnricoFermi's apparent paradox and some of the proposed resolutions are thetopic of this lecture.  I will review the Fermi Paradox and describe themost common possible resolutions.  The Fermi Paradox is useful inhelping to frame the question of extraterrestrial life, even if we sofar have no answers.  At the end I only touch on the Rare EarthHypothesis, but this is a very nuanced question which requires a wholeother lecture to explore that I have not had time to fully prepare forduring this busy quarter.  Recorded live on 2009 Nov 30 in Room 1005Smith Laboratory on the Columbus campus of The Ohio State University.

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.

Lecture 42: The Fermi Paradox

The geological revolution revealed that the Earth is of great antiquityand yet has a history we can read in the land.  We will discuss ideas of cyclic and linear time, historical versus physical age estimates, the discovery of geological time, andradiometric dating methods that give us our present estimate of4.54+/-0.05 Gyr for the age of the Earth.  Recorded live on 2009 Sep 30in Room 1005 Smith Laboratory on the Columbus campus of The Ohio StateUniversity.

The geological revolution revealed that the Earth is of great antiquity and yet has a history we can read in the land. We will discuss ideas of cyclic and linear time, historical versus physical age estimates, the discovery of geological time, and radiometric dating methods that give us our present estimate of 4.54+/-0.05 Gyr for the age of the Earth. Recorded live on 2009 Sep 30 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.

Lecture 6: The Geological Revolution - Deep Time and the Age of the Earth

How have we pieced together the geological history of the Earth?This lecture reviews the different types of rocks and the cycleof transformation between them, with particular emphasis on stratigraphy.  I will outline the 4 major Eons in Earth's history, and focus on theearliest Hadean Eon which proceeded from the formation of the Earth to the end of the epoch of Heavy Bombardment.  The Hadean Eon saw the formationof 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.

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.

Lecture 11: The History of the Earth

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.

Astronomy 161 & 162

Thanks for these podcasts. Been listening to them for 9hrs straight now :D

Thank you

Astronomy 141, Life in the Universe, is a one-quarter introduction to Astrobiology for non-science majors taught at The Ohio State University. This podcast presents audio recordings of Professor Richard Pogge's lectures 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.

Astronomy 141 - Life in the Universe - Autumn Quarter 2009

If we ever detect life elsewhere, how will we go visit?  This lectureconsiders the challenges of interstellar travel and colonization.  Theproblem is one of basic physics (the enormous energy requirements ofstar flight) coupled with the vast, irreducible distances between thestars.  I will describe various starship concepts that use reasonableextrapolations of current technologies (nuclear propulsion and solarsails), ignoring for our discussions science-fiction exotica likefaster-than-light drives and wormholes.  My interest is in thescientific aspects of the problem, not an exploration of speculativefiction. I then turn to interstellar colonization, and how evena relatively modest star-flight capability might allow a determinedcivilization to colonize the entire galaxy very rapidly.  This hasimplications for how we might interpret the results of Drake Equationtype arguments about the frequency of intelligent life in the Galaxy,and leads to the Fermi Paradox that will be the topic of the nextlecture.  Recorded live on 2009 Nov 25 in Room 1005 Smith Laboratory onthe Columbus campus of The Ohio State University.

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.

Lecture 41: Interstellar Travel and Colonization

An introduction and review of the basic notation and physical units we will beusing throughout this course.  In particular, we will be using theMetric (SI) system for lengths, masses, times, and temperatures, andspecial astronomical units for distances (AU and Light Years) and masses(Earth Masses and Solar Masses) appropriate when discussinginterplanetary and interstellar scales.  Recorded live on 2009 Sep 24 inRoom 1005 Smith Laboratory on the Columbus campus of The Ohio StateUniversity.

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.

Lecture 2: Astronomical Numbers

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, ourhopes and our fears, than about extraterrestrial life.  The scientificinquiry we are undertaking must therefore approach the problem from adifferent direction.  Recorded live on 2009 Sep 25 in Room 1005 SmithLaboratory on the Columbus campus of The Ohio State University.

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.

Lecture 3: Imagining Other Worlds

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

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.

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

How did life arise from non-life?  Frankly, we don't know, but currentexperimental work is aimed at trying to understand how it might work inbiochemical terms.  This lecture sets out the problem of "abiogenesis",and describes our current thinking about the likely origins of life onEarth.  We will review the classic Miller-Urey experiment, and look atits insights and limitations, discuss meteoritic sources of amino acids,and the basic requirements needed for protolife.  I will then describein outline two scenarios that are active areas of origins research: theRNA World model and the Metabolism First model.  Finally, I will verybriefly mention Exogenesis and Panspermia, which don't really addressthe problem of abiogenesis so much as move it elsewhere.  Recorded liveon 2009 Oct 20 in Room 1005 Smith Laboratory on the Columbus campus ofThe Ohio State University.

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.

Lecture 19: The Origin of Life on Earth

In this lecture we step back and look at the history of life on Earthfrom the first signs of life at start of the Archaean Eon 3.5 billionyears ago to just up to the present day.  We will review the appearanceof photosynthesis and the rise of oxygen in the atmosphere in theProterozoic, the appearance of the first eukaryotes and sexualreproduction, and the Cambrian explosion of plant and animal species atthe start of the Phanerozoic Eon, and briefly review the changes in lifeto the present day from the Cambrian Explosion to the colonization ofland by plants and then animals.  Most of the lecture will be where mostof the time was spent, in the early, microbiological Earth.  Recordedlive on 2009 Oct 21 in Room 1005 Smith Laboratory on the Columbus campusof The Ohio State University.

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.

Lecture 20: The History of Life on Earth

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

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.

Lecture 39: The Drake Equation

Cosmology is the study of the entire Universe as a physical system.  Thepast century has witnessed a revolution in cosmological thought that has revealed the vastness of space and the depths of cosmic time, a revolutionthat 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 timesince the Big Bang, and the origin of the elements.  We will return tomany of these topics later in the course, but this presents the bigpicture.  Recorded live on 2009 Oct 2 in Room 1005 Smith Laboratory onthe Columbus campus of The Ohio State University.

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.

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

What are the first recognizable forms of life that we find in thegeological record?  How far back can we go in geological time and stillfind life?  This lecture reviews three lines of evidence that haveemerged in recent years to suggest that life may have emerged very earlyon the young Earth, perhaps within a few hundred million years of theend of the epoch of heavy bombardment.  I will describe fossilstromatolites, microfossils, and carbon isotope data that are used toexplore these questions.  Recorded live on 2009 Oct 19 in Room 1005Smith Laboratory on the Columbus campus of The Ohio State University.

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.

Lecture  18: The First Living Things on Earth

We end our exploration of life on the Earth with a look at death in thefossil record.  This lecture looks at the role asteroidal impacts haveplayed in the history of the Earth, and their possible role in massextinction events in the fossil record.  We will discuss near-earthasteroids, historical impacts, and the K-T event in which a massiveasteroid impact caused a mass extinction of species that included allnon-avian dinosaurs among its victims, opening up the biosphere to thedominance of mammals.  We'll look at other mass extinctions during thepast 500Myr, and talk about whether extinction-class impacts are in ourfuture.  Recorded live on 2009 Oct 22 in Room 1005 Smith Laboratory onthe Columbus campus of The Ohio State University.

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.

Lecture 21: Impacts and Extinction

Modern science was borne of an effort over many centuries to understandthe motions of celestial bodies.  The Copernican Revolution of the 16thand 17th centuries was the crucial moment in history when we finallyunderstood the nature of celestial motions, and opened the door to themodern world.  This lecture reviews the problem of celestial motions,the two competing models for explaining them, and the final revolutionin thought starting with Copernicus and ending with Newton.  Mid-lecturemy classroom AV system lost power, and the recovery slowed things down abit.  These are recorded live, after all.  This lecture was conducted on2009 Sep 28 in Room 1005 Smith Laboratory on the Columbus campus of TheOhio State University.

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.

Lecture 4: The Copernican Revolution

What is the nature of matter, and how did we come to understand thechemical elements and atomic structure?  This lecture is a brief andselective overview of the history of our understanding of the nature ofmatter and chemistry.  We will also introduce spectroscopy andradioactivity, two very powerful tools that came out of the chemicalrevolution that are crucial for the inquiry in this class into thequestion of life on other worlds.  Recorded live on 2009 Sep 29 in Room1005 Smith Laboratory on the Columbus campus of The Ohio StateUniversity.

What is the nature of matter, and how did we come to understand the chemical elements and atomic structure? This lecture is a brief and selective overview of the history of our understanding of the nature of matter and chemistry. We will also introduce spectroscopy and radioactivity, two very powerful tools that came out of the chemical revolution that are crucial for the inquiry in this class into the question of life on other worlds. Recorded live on 2009 Sep 29 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.

Lecture 5: The Chemical Revolution and the Nature of Matter

What stars are near the Sun?  Now that we have some idea of what we arelooking for - rocky planets in the habitable zones of low-massmain-sequence stars - what are the prospects near the Sun?  This lectureexamines the hunting ground for planets, the nearby stars that make upthe Solar Neighborhood.  I will describe our nearest neighbor, theProxima Centauri/Alpha Centauri triple system, and then look at theproperties of our nearest stellar neighbors.  What we will find is thatG-type stars like the Sun are uncommon, only about 7% of all nearbymain-sequence stars.  Red dwarfs, on the other hand, are very common,about 75%.  To find Sun-like main sequence stars, we will have to extendour search to larger distances into our Milky Way galaxy proper.Recorded live on 2009 Nov 16 in Room 1005 Smith Laboratory on theColumbus campus of The Ohio State University.

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.

Lecture 35: The Solar Neighborhood

What happens to a star when it runs out of hydrogen in its core?  Thislecture describes the post main-sequence evolution of stars.  Whathappens depends on the star's mass.  Low mass stars swell up into RedGiants, and eventually shed their envelopes and end their lives as whitedwarf stars.  High mass stars become Red Supergiants, and if largeenough, end their lives in a spectacular supernova explosion that leavesbehind a neutron star or black hole.  The explosion itself createsmassive quantities of heavy elements, which then seed interstellar spacewith metals to be incorporated into subsequent generations of stars.Recorded live on 2009 Nov 12 in Room 1005 Smith Laboratory on theColumbus campus of The Ohio State University.

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.

Lecture 33: The Deaths of Stars

Why do stars shine?  How long do they shine?  This lecture describes thephysics of stars on the main sequence, describes the mass-luminosityrelation of main sequence stars, introduces nuclear fusion power and thenuclear fusion lifetimes of stars.  From this we gain an importantinsight into one of the criteria we might apply to the search for lifearound other stars: we want planets around low-mass main sequence starsthat can shine more or less steadily for more that 500 Myr to 1 billionyears - maybe longer if our goal is to find intelligent life.  Recordedlive on 2009 Nov 10 in Room 1005 Smith Laboratory on the Columbus campusof The Ohio State University.

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.

Lecture 32: The Lives of Stars

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 SmithLaboratory on the Columbus campus of The Ohio State University.

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.

Lecture 27: Is There Life on Mars?

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