PROPERTIES OF THE SUN
Luminosity- total energy radiated by the Sun (can be calculated from the
fraction of that energy that reaches Earth.
Solar constant- the amount of energy that reaches Earth (1400 W/m sq.)
Energy balance- the rate at which
-The great contribution of Nicholas Copernicus was to create a detailed model of our solar
system with the Sun rather than Earth at the center.
-The great contribution of Tycho Brahe was to observe planetary positions with sufficient
EARLIEST LIFE FORMS
Life probably arose on Earth more than 3.85 billion years ago, shortly
after the end of heavy bombardment.
Evidence comes from fossils, carbon isotopes.
Fossils in Sedimentary Rock
Relative ages: deeper layers formed earlie