More heavily cratered regions are older

More heavily cratered regions are older
 Differentiation: heavier elements sink to the middle
8. Sun
 Location of the sun at sunset: North west in CU
 Zenith: Directly Ahead
 98% hydrogen and helium gas
9. Half life
 1 half life-> 50, 2 half lives -> 25, 3 half lives -> 12.5
 Speed of light = 3.97x10^13
10. More on planets’
 Mercury , the smallest planet, is only a little bigger than Earth’s moon, and like
the Moon, is covered in craters.
 Venus is the closest planet in size and mass to Earth, but its thick, toxic
atmosphere produces a runaway greenhouse effect that leaves the surface hot
enough to melt lead.
 Earth’s oceans—the presence of liquid water in abundance on the surface—make
it unique in the solar system.
 Mars is a frozen desert planet. Like Earth, it has seasons, weather, polar ice caps,
volcanoes, and canyons
11. Comets/Asteroids

 Comets have 3 parts (Nucleus, coma, tail) (only have tails when by sun)
 Stonys (94% of meteorite falls) (rocky composition)