Introduction: The Earth today, and the alien worlds around it 1. Before Earth o Formation of the solar system: temperature and compositional gradients in the cloud o Planetary rings as analogs to our protoplanetary disk · Lords of the rings, moons and waves o Views of extrasolar disks and what they tell us of our roots · Seeing our past through Hubble and Spitzer o The "snow line" and structure of the early Sun''s nebular cloud o Our solar system''s habitable zone · Habitable zones around other stars o Our place in the Milky Way galaxy · The galactic habitable zone 2. Earth=Mercury: Earth as a molten world o Terrestrial planets begin as molten balls of rock § Accretion and differentiation § Earth formation: cold or hot? § The importance of layers o Mercury''s beginnings: raining rock and metal § The sky is falling: metallic vs stony asteroids, cometary ices o How Mercury and the Earth differ, solar influences o Shared heritage, the echoes of planet Mercury within the rocks of Earth · [news inset: newly discovered mineral inside a diamond hints at the nature of Earth''s deepest mantle] 3. Earth=Venus: Our planet as a Dante-esque oven o Ocean vs desert, and where the balance lies o Oceans condense from atmosphere o Earth before rust: land and sea without free oxygen · [news inset: Earth''s evil twin: why did Venus end up so different from Earth? Asteroid impacts may be the culprit] o New dawn for Venus: upcoming missions and what they may soon tell us 4. Earth and the Asteroid belt: the impact of an uneasy relationship during the great solar system cleanup o Are the asteroids a failed planet? o What the asteroids added to the Earth''s mix § Specific minerals, water, gases o Birth of the Moon. § Theia impact o [inset: Large low-shear velocity provinces: evidence for Theia remnants?] o The Moon''s importance for tides, axial stabilization, etc o The Earth/Jupiter relationship, a natural force-field · [news inset: missions to the asteroids: can we move the rocks?] · [news inset: what we''ve learned from Ryugu and Itokawa samples] 5. Earth=Titan o Titan as a chemical proxy for the early Earth (nitrogen and methane, a winning combination?) § Titan''s methane as starting point for complex organics § Titan as a snapshot of Earth''s prebiotic chemistry · Photochemistry leads to building blocks of life · Earth evidence wiped out, but Titan''s is frozen for us to explore o The great mystery: first life § Was the atmosphere of pre-biotic Earth reduced or oxidized? § Hydrogen cyanide and the "cyanosulfidic" pathway to life § Panspermia and its problems; cosmic dust and precursors to amino acids § Carbonaceous chondrites, comets, and how they relate to life o Earth as a nursery § Chemistry and energy in the beginnings of life § Life under pressure: synthesis of organic matter from inorganic molecules near submarine hydrothermal vents and geothermal pools o Earth''s oxygenating event and how biology sculpts a planetary environment o Titan as a primordial Earth analog § Many parallels with ancient Earth · Reduced atmosphere; early Titan warmer and richer in oxygen, similar to Earth · Primary chemical composition and vertical profile of the atmosphere · Physical and chemical combinations (including thymine and cytosine production at Titan) · Energy sources (sunlight, Saturn radiation, possible cryovolcanism) · Atmospheric greenhouse effects § Life''s building blocks? · Cell membranes from acrylonitrile · Photochemically produced organic chemistry, amino acids and tholins (Miller- Urey and follow-on experiments) · Three places for water on Titan · Carbon-based life without accessible water · Ammonia instead of water: N chemistry and pseudo biochemistry · Where is the methane coming from? § Is life in the universe inevitable? Dinosaurs to protozoans, a rich menagerie § Future Titan: a new birthplace? · [news inset: changes in Earth''s spin may have led to oxygen buildup] 6. Earth=Mars: the "Snowball" or "Slushball" Earth o The past lives of Earth and Mars § Water, water everywhere, but not a drop to breathe: oxygen-poor watery environments of early Mars and Earth § Continent configuration: how landmass arrangement affects climate (did Mars have plate tectonics?) § The "lost" billion years of Earth geology § Making a snowball: balance between greenhouse effects and runaway freeze · The role of sea-ice dynamics, wind, etc · The role of the carbon cycle and volcanism · Escape from the ice palace: the blossoming of oceans and freeing of metals · Links to the Cambrian explosion? § Raptian group of Canadian Cordillera: glaciers sandwiched between limestone, and other equatorial glacier evidence of snowball Earth § Earth''s oxygenating event and how biology sculpts a planetary environment § The progression of life and its effect on the environment · [news inset: dinosaurs may have gotten huge during a rainy era] o Martian glaciers and echoes of Earth § Orbital obliquity and past glaciation § Morraines, scour marks and hanging valleys § Rock glaciers, active even today? · Kasei Valles, western sides of Tharsis volcanoes (for example) o Compare to ocean moons: Europa, Ganymede, Enceladus, others § Why did the ocean moons not freeze solid? Tidal and radiogenic heating o Earth''s Moon and axial stability (Stromatolite evidence of Earth''s stable orbit) 7.

Distant Earths: exoplanets with potential o What we''ve found (the statistics) § Worlds orbiting red dwarfs, and the dangers of flares · [news inset:Our own Sun''s flares in history] o&nbs.