1: Is There Life Elsewhere in Our Universe?

• Is there life in our universe? As you get an overview of the course-including the five major questions it will endeavor to answer-consider the possibility that life exists in some form in the cosmos. Learn how exponential growth in technological developments is enabling breakthroughs that were recently impossible.

2: Bang! A Universe Built for Life

• How did we go from a dead universe to a universe full of life? Begin to answer this question by evaluating the scientific evidence supporting the big bang theory of the universe's creation, and learning the role stars play in creating carbon and the key elements needed for life.

3: A Star Is Born-Forming the Solar System

• How do you make a planet? Look at what is currently known about the process by which our solar system's planets formed from billions of small planetesimals, as well as how this process left the universe teaming with asteroids and comets that play an important role in life on Earth.

4: The Early Earth and Its Moon

• Follow a series of mishaps and cataclysmic events that set the stage for early Earth to finally flourish with life after 650 million years. Learn how a hot core, a large moon, and other properties on Earth helped lead to an active biosphere.

5: Impacts-Bringers of Death ... or Life?

• Delve into the Late Heavy Bombardment period that kept Earth stuck in a lifeless state for 650 million years, then watch an animation demonstrating the K-T impact event that wiped out the dinosaurs. Consider whether it's possible to protect ourselves from asteroids hurtling toward Earth-and why Hollywood gets it all wrong.

6: Evidence of the First Life on Earth

• How has the Earth managed to stay within a moderate range of temperatures for billions of years, despite the atmosphere's wild fluctuations in oxygen? Study how convection, greenhouse gases, and the carbon rock cycle contribute to a powerful system of checks and balances that keep Earth's climate consistent with supporting life. Also, meet some of Earth's earliest life.

7: Common Themes for All Life on Earth

• Now that you have covered the key elements necessary for life to exist, take a closer look at the things all life on Earth shares. Learn why the Biosphere 2 experiment in the 1990s failed, examine the behavior of microbes-the most important constituents of our biosphere-and trace life back to your universal ancestor.

8: Origin of Terrestrial Life

• For something to be "living," it generally must use energy to drive chemical reactions, be capable of reproduction, and undergo some degree of evolution. Sort through science's best educated guesses for how and why life sprang from nonliving matter, including lessons from the groundbreaking Miller-Urey experiment. Watch an animation of protocells growing and splitting to replicate geneti...

9: Astrobiology-Life beyond Earth

• Why is liquid water so important? Why do icebergs float? After quickly reviewing what you have learned about the requirements for terrestrial life, take a closer look at the "liquid water carbon chemistry juggernaut," which allows organic life to thrive on Earth. Consider whether other liquids could operate as solvents for life.

10: Has Mars Always Been Dead?

• Mars ranks as NASA's number one priority in the search for exolife. Here, you delve into why Mars is so intriguing to astrobiologists and what the search has found to date. Start with a comparison of Mars and the Earth, then watch the first-ever observation of water ice on Mars sublimating into vapor.

11: Evidence for Fossilized Life from Mars

• In 1996, NASA claimed to have found evidence of past life on Mars inside an unassuming meteor. Evaluate the three points scientists gave in support of the microbes being Martian in origin to determine their validity. Then, learn about the theory of panspermia and meet the water bear, a tiny animal capable of surviving the extreme conditions of outer space.

12: Could Life Ever Have Existed on Venus?

• Venus is the closest planet to the Earth and the next planet moving toward the sun, so it is a logical place to look for life. However, Venus is extremely hot and dry. Could life ever have existed? Explore the nightmarish conditions on Venus and learn why all the water vanished.

13: Liquid Assets-The Moons of Jupiter

• Gas giant Jupiter is unlikely to inhabit life-but what about its moons? Look quickly at the importance that Galileo's discovery of Jupiter's moons had for the powerful Medici family before moving on to examine the connection between the moons' mean motion resonance and the possibility of subsurface life existing in the ice-covered oceans of Europa, Ganymede, and possibly, Callisto.

14: Liquid on Titan and Enceladus

• Continue traveling to the cold gas giant Saturn and its large moon, Titan. Watch a video featuring actual data taken by the Huygens Probe as it pierces the thick atmosphere and lands on the surface of this frozen world, and witness the surprising Earth-like structures this probe and its mother ship found on their journey to Saturn's moons.

15: Discovery of Extrasolar Planets

• Is our solar system common or rare? As you investigate planets orbiting around other stars, learn how the use of adaptive optics allows extrasolar planetary scientists to discover new alien solar systems with ground telescopes, and explore the three main ways astronomers detect planets: small "radio velocity wobbles," "transits," and direct imaging.

16: The Kepler Spacecraft's Planets

• The Kepler mission is changing everything we know about extrasolar planets. Learn how this supersensitive-imaging instrument works to monitor 157,000 stars continuously for years and what it has uncovered since launching in 2009. But first, review the transit effect created when a parent star crosses its orbiting planet.

17: A Tour of Exotic Alien Solar Systems

• Based on data from Kepler, there are thought to be four main classes of transiting planets: hot Jupiters, hot Neptunes, super-Earths, and Earth-like planets. In this lecture, you will look at detailed highlights of the most fascinating examples of each of these new classes of alien worlds, from most to least massive.

18: Extraterrestrial Intelligent Life

• How common is simple life is in our universe? What about intelligent life? Start to answer these questions by estimating the prevalence of prokaryotic single-celled microbes and reviewing the process of evolution. Evaluate arguments in the book Rare Earth by Ward and Brownlee claiming that while microbial life is common, only Earth has intelligent life. Finally, touch on how aliens might appear.

19: SETI-The Search for Intelligent Life

• In a lecture that "skims right on the edge of science fact and science fiction," delve into the search for extraterrestrial life, or SETI, as the method used to gauge the likelihood of intelligent communicating civilizations is known. Look closely at the Drake Equation-the mathematical rubric commonly used in the field of SETI-and consider the challenge of communicating across our enormo...

20: The Fermi Paradox-Where Is Everyone?

• After 50 years of SETI, we have zero hard evidence of alien civilizations, "cosmic wanderlust" resulting in Earth visitations, or UFOs being extraterrestrial in nature, despite-or perhaps because of-the expansiveness of the galaxy. Speculate on reasons for, and solutions to, this so-called Fermi Paradox.

21: Space Travel-A Reality Check

• Space is so vast that inventing a method of faster-than-light travel is the only way humans could conceivably travel the cosmos conveniently. How hard is space travel, really? In this mind-bending lecture, review the obstacles to space travel and consider their theoretical solutions-from combining matter and antimatter into energy, to taking "short cuts" via warp drive and wormholes.

22: Terraforming a Planet

• Terraforming is a new scientific concept whereby an uninhabitable planetary environment is engineered to become more Earth-like to support human life. Explore how this complex process would play out on the two planets considered potential candidates, Mars and Venus, to fully understand the individual steps involved and the technologies necessary to achieve those steps.

23: The Future of Terrestrial Life

• Professor Close highlights why we shouldn't be complacent about the long-term viability of Earth and presents the timescale in which humans will need to leave Earth or become vulnerable to extinction. Inspect historical evidence indicating that Earth is warming, and learn what will happen to the atmosphere in the future.

24: The Search for Another Earth

• Now that you've seen why humanity will eventually have to leave Earth, consider astronomers' next steps, challenges, and planned missions. Examine why specialized optical systems called coronagraphs are necessary to detect habitable Earths, and how the use of direct imaging spectra is crucial to identifying whether the biomarkers of life are present on other worlds.

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