Chapter 9 Flashcards
What properties affect a planet’s outcome?
- Size
- Irradiation (distance from sun)
- rotation
- and other properties to a lesser extent
What does the interior look like for terrestrial planets?
Earth and venus are roughly the same in terms of interiors Mars and Mercury are vastly different mars has a large lithosphere whilst mercury has a large core.
What makes up the interior of a planet? from least dense to most dense
- Rocky crust (lower density)
- Litosphere (part of crust and mantle)
- Mantle (medium density)
- Metal core (high density)
Why are planets spherical?
After a certain size, the force of gravity on a planet is greater than the tensile forces within the rock. this deforms the shape into a sphere.
What were the dominant sources of heat in Earth’s early history?
Conversion from GPE to heat was main this was done through the accretion of planetesimals and differentiation converts PE to heat. Currently, radioactive decay produces the most heat
What three ways are heat transmitted or loss
- Convection
- Conduction
- Radiation
What does heat lead to?
heat drives geologic activity. This is because heat leads to convection which means that hot rocks rise and cool rocks fall.
What is the difference between smaller planets and larger planets, in terms of heat?
- Smaller planets cool faster so tectonic and volcanic activity ceases. The lack of volcanism means little outgassing and low gravity allows gas to escape more easily. No atmosphere means no erosion.
- Warmer interiors mean that tectonic and volcanic activity continues. Due to volcanism, outgassing produces a strong atmosphere and strong gravity holds it so that erosion is possible. The core may be molten which also creates a magnetic field if rotating fast enough.
What are the three requirements for a magnetic field
- Electrically conducting field
- Convection in fluid layer
- moderately rapid rotation
What are the four main geological processes?
- impact cratering - impacts by asteroids or comets
- volcanism - eruption of molten rock onto surface
- tectonics - disruption of a planet’s surface by internal stress
- erosion - surface changes made by wind, water, or ice
What is the main source of atmosphere on terrestrial planets?
outgassing is teh most importnat. There is also evaporation of surface liquids and ice and impacts of particles and photons on worlds without significant atmospheres can also release gasses from surface
What are tectonics and how do they work?
Convection in the mantle causes stress in the crust, pushing and pulling the crust together or pulling it apart and creating mountains or valleys.
How does erosion work?
erosion sculpts rocks, forming valleys, dunes, etc. this however requires an atmosphere (wind) and presence of water (liquid water and glaciers)
What causes erosion
- size the bigger the more outgassing the more erosion
- distance from the sun if too close then too hot for erosion if too far then too cold for erosion
- rotation the faster planet rotates the more wind it has.
Why are parts of the moon so smooth
- initially cratered surface
- large impacts damaged the lithosphere
- Molten rock leaks up and floods the large crater
- rock solidifies leaving a smooth surface.
Earth’s geology?
Earth’s geology is driven by tectonic plates. In specific convergent plates and divergent plates.
Olympus Mons creation on land near Hawaii
based on tectonic motions
temperature with altitude?
forms an s line almost
What is the Carbon cycle
- atmospheric CO2 dissolves with rainwater
- rain erodes materials that flow into the oceans
- minerals combine with carbon to make rocks on the ocean floor
- continental drift carries carbon-rich rock down into the earth’s mantle
- Rock melts in the mantle and Co2 is outgassed back into the atmosphere through volcanoes.
