Chapter 7 Earth and the Terrestrial Worlds. Understanding the similarities and differences between the planets of the solar system, in particular, the four terrestrial planets, can tell us how Earth becomes the way it is today. The similarities and differences of the terrestrial worlds.
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Internal heating causes Mantle Convection---hot rock rises to the top and cools off, cool rock sinks to the bottom, resulting in the cooling of the planet…Heating of the Terrestrial Planets
Lines indicate points with equal magnetic field strength
We can study the interior structure of the Earth by studying how seismic waves travel through Earth…
Seismic waves propagate through Earth in two modes:
P wave can travel through any material.
S wave cannot travel through liquid.
Processes shaping the surface of the planets
Erosion is a blanket term for a variety of processes that break down or transport rock through the action of ice, liquid, or gas.
are all examples of erosion.
Mauna Kea and Mauna Loa are very tall, but as we move toward the west, the volcanoes gets lower and lower…
Mercury and the Moon don’t have an atmosphere because they are too small. Their weak gravitation field is not enough to keep the gas.
Given the same temperature…
Given the same temperature, the thermal velocity of lighter gases are higher compared with velocity with heavier gases. Therefore, the lighter gases have better chance of acquiring a speed greater than the escape velocity of the Earth and escape…(remember that the escape velocity of the Earth is about 14 km/sec, and independent of the mass of the escaping object).
Similarities between Mercury and the Moon:
Surface of Mercury looks very similar to the Moon
Venus and Earth are very similar in size, and Mars is a little smaller. Their surface features are somewhat similar also – they both have few impact craters, and they all have volcanoes and evidence of tectonic activities.
Although there is a very large difference in the amount of gases on Venus and Mars, their chemical compositions are very similar – high percentage of CO2
Among the three large terrestrial worlds, the surface environment of Earth is very unique.
The “No Greenhouse Temperature” of a planet depends on its distance from the Sun, and its albedo (or the reflectivity of a surface or a body)…
However, the presence of an atmospheres can drastically change the surface temperature of a planet.
Objects with temperature of a few hundred degree Kelvin emit thermal radiation in the IR
Depending on the composition of the atmosphere, the effect can be very different
T = 740 K.