Astronomy: Life in the Universe 09/11/2013
Extraterrestrial life – life beyond earth
Astrobiology – combination of astronomy (study of the universe) and biology (study of life)
Studying the conditions conductive to the origin and ongoing existence of life.
Looking for such conditions on other planets in our solar system + around other stars.
Looking for the actual occurrence of life elsewhere.
Microbes – single celled organisms too small to see with naked yee. Stretch the extreme living
conditions on Earth, first life forms on earth and are anywhere life exists on earth.
Scientific model – Conceptual representation whose purpose is to explain and predict observed
Theory – When a powerful yet simple model makes predictions that survive repeated and varied testing.
Cannot prove theories are correct.
Orbital period – time it takes for an object to complete one orbit.
Apparent retrograde motion – when planets reverse direction and move westward relative to the
stars opposed to eastward, usually happens from a few weeks to a few months.
Stellar parallax – annual shifts in star position.
Occam’s Razor – The idea that scientists should prefer the simpler of two models that agree equally
well with observations.
Atomists – Believed that our world formed among an infinite number of indivisible atoms and this infinity
implied the existence of other worlds.
Aristotelians – Believed that all Earth must have fallen to the center of the universe, which rationalized
the belief in a geocentric universe and the belief that the heavens were fundamentally different from Earth,
which implied that earth must be unique in which case no other worlds or other life could exist.
Geocentric model (Ptomlemy) – (Earth Centered) A spherical Earth at the center of a great
Heliocentric (Copernicus) – Sun in the center.
Pillars of Science: (ways to learn about the world)