1. Why is life like on Earth so rare in our universe? -life needs habitable conditions -we haven’t been able to examine very many other planets 2. How is Earth so special among other solar bodies? -it supports life!

3. How is Earth well-suited for the study of astronomy? -our atmosphere is transparent so we can see out -our location in the Milky Way-our view of other galaxies & the rest of the Universe isn’t obstructed by the stars in our own galaxy

4. How do changes in technology and society lead to new and better discoveries? -better technology=better tools for looking at the Universe and taking measurements

CORIOLIS EFFECTGREENHOUSE EFFECT  T he rotation of the planet pushes the air sideways-affects global wind patterns  The “greenhouse” gases absorb heat, then re-emit it in all directions, warming the atmosphere nd land

ACCRETION The gathering of “planetesimals” (little planets) and the accumulation of gases in the solar nebula.

PLANETISMAL PROTOPLANETARY DISC

NEBULAR THEORY NEBULA  the most widely accepted model explaining the formation and evolution of the Solar System  an interstellar cloud of dust, hydrogen, helium and other ionized gases.

PROTOSTARPROTOSUN  A contracting mass of gas that represents an early stage in the formation of a star, before nuclear fusion has begun.  The gaseous cloud that condensed to form our Sun

OUTGASSING T he outpouring of gases from the earth's interior

The Sun and all the objects that orbit it.

 The theory that explains the origin of the Universe.

 Thermal escape-a molecule moves fast enough to escape gravity  Bombardment  Atmospheric cratering  Condensation  Chemical reactions

SIMILARITIES:  Sun warms the atmosphere at the equator and creates convection cells  Clouds are always present  Clouds contain water  Rain forms and falls DIFFERENCES:  On Venus-  Clouds contain Sulfuric acid mixed with the water(both of these are replenished by volcanic eruptions)  Rain that falls evaporates long before it hits the ground

 The theory of how the universe was formed  Timeline:  Universe began as an infinitesimally small point of incredibly hot, dense matter/energy  Exploded-a sudden dramatic expansion  Matter out numbered antimatter  Subatomic particles formed, then elements began to form-this took between 500,000 years for atoms to start creating elements  Then 1 billion years to start forming stars/planets.  Happened 13.7 billions years ago

 One of the most important is the Cosmic Microwave background  Scientists predicted it, then were able to measure it with the COBE (Cosmic background explorer) satellite  Satellite was a big success for Big Band theorists- there is some radiation left over from the Big Bang and was as scientists predicted.

 Earth & Venus

 The smallest terrestrial planet  Made of: helium, sodium, oxygen  No weather-there’s not enough atmosphere!

 Made of: mostly Carbon dioxide (96%) and a little Nitrogen (3.5%)  Weather-slow winds with no big storms and lots of acid rain from sulfuric acid clouds, but the rain never reaches the ground-it evaporates quickly  No seasons because it isn’t tilted relative to the Sun  Rotates slowly

 Made of: mostly Nitrogen (77%) lots of Oxygen (21%), argon, water vapor, and other trace elements  Wind over the whole planet-global wind patterns, storms, hurricanes  Movement of winds affected by:  Heating of the atmosphere  Coriolis effect  Clouds made of water vapor  Lots of precipitation

 Thin atmosphere, created by bombardment  Gravity affects the Earth  Creates tides  Helps stabilize us in our orbit

 Thin atmosphere  Made of: mostly Carbon dioxide (95%), Nitrogen (2.7%) and Argon (1.6%)  Weather-some wind and dust storms, but there is very little pressure and the atmosphere is very thin

 Largest planet in the solar system  Magnetic field that protects its moons and extends all the way to Saturn  Gaseous planet, formed by gas accretion