How the Earth was formed/The Motions of the Earth and Moon Flashcards
(28 cards)
planets were gradually formed from planetesimals that were results of accretion
how the Earth may have formed
Core Accretion Model
a process in which different elements accumulate in separate areas due to their physical or chemical properties
Chemical Differentiation
How did the Earth form its layers?
Chemical differentiation made heavier elements (Fe, Ni) sink to the center and formed its core while lighter elements came to the surface. A primitive crust was then formed as temperatures began to cool.
around 4.5 billion years ago, a large Mars-sized celestial body made impact w/ the Earth; undifferentiated Earth materials ejected and accumulated into the Moon
this may have also caused the Earth’s 23.5 degree tilt
Giant Impact Hypothesis
How did life on Earth start?
- Asteroids with atmospheric, oceanic, and biological components may have bombarded the Earth, setting the stage for life on Earth
- As temperatures cooled, gases from the interior were released, resulting in the first atmosphere
- Atmospheric water vapor condensed, producing torrential rains and vast oceans
- Cyanobacteria/aerobic bacteria increased oxygen in the atmosphere
when a body spins on its axis
Rotation
imaginary line that passes through the center of the Earth, from the North Pole to the South Pole
Axis
tilt of the Earth’s axis
23.5 degrees
duration of one complete Earth rotation
23 hours, 56 minutes, and 4 seconds
the change in axial tilt
Obliquity
41,000 years is equal to ____
the axial tilt of Earth can vary every 41,000 years
One Milankovitch Cycle
shortest day of the year
Winter Solstice
longest day of the year
Nick Joaquin 😛
Summer Solstice
when day and night are equal in duration
Equinox
Earth orbiting around the Sun
Revolution
duration of one complete Earth revolution
w/ an average speed of 30 km/s
365 days, 6 hours, and 9 minutes
Earth is farthest from the Sun
Aphelion
‘ap-‘ = “away from”
Earth is closest to the Sun
Perihelion
‘peri-‘ = “near”
the change in direction in which the axis points
Axial Precession
one sidereal month is equal to ____
the time it takes for the Moon to complete one revolution around the Earth
27.32 days
one synodic month is equal to ____
the time it takes for the Moon to cycle through its phases
29.5 days
27.32 days
one sidereal month
29.5 days
one synodic month
what causes the Moon’s phases?
- the Moon’s motion
- amount of sunlight reflected off the surface
