Ch. 8: Earth as a Planet

Ch. 8: Earth as a Planet

Earth’s Atmosphere is layered Earth’s Atmosphere is layered. We live in the troposphere, which has most of the mass and weather.

Convection heats the lower atmosphere, distributing heat from the ground.

Factors include: Water vapor Clouds Snow cover Carbon dioxide Methane The Greenhouse Effect plays a major role in heating the Earth’s atmosphere. Factors include: Water vapor Clouds Snow cover Carbon dioxide Methane CFC gases Dust and pollution Desertification Agriculture City “heat islands”

Global Warming is definitely occurring, but this may be due to several reasons.

Global Warming may be due partly to increasing carbon dioxide levels which increase the Greenhouse effect.

Increasing carbon dioxide levels have been measured on the Hawaiian volcano, Mauna Loa.

Earth’s interior is revealed by seismology, the study of earthquakes Earth’s interior is revealed by seismology, the study of earthquakes. Earth is layered. A layered object: Inner core Outer core Mantle Crust Hydrosphere Atmosphere Magnetosphere

Observation of Seismic Waves due to earthquakes reveals the interior structure of the Earth

Global Plates move slowly – plate tectonics The motion at their boundaries causes earthquakes.

Earth is the only planet we know of that has Plate Drift causes many effects: earthquakes, rift valleys, mountain chains, volcanoes, mid-Atlantic ridge, etc. Earth is the only planet we know of that has these tectonic features (drifting continents).

Earth’s Magnetosphere varies in size, depending on the solar wind.

Van Allen Belts, named after James Van Allen of the Univ Van Allen Belts, named after James Van Allen of the Univ. of Iowa, who sent instruments up on early U.S. spacecraft.

There are also aurorae around Jupiter, Saturn, Uranus, and Neptune. The Aurora Borealis are due to charged particles trapped in the Earth’s magnetic field, causing air molecules to glow. There are also aurorae around Jupiter, Saturn, Uranus, and Neptune.

Cratered Worlds: The Moon

Earth’s Moon: the interior is not well understood. Missing from the Moon are these features: Hydrosphere Atmosphere Magnetosphere

Full Moon, Near Side – we see maria (old lava flows)

Far side of the Moon.

Moon craters, maria, and highlands.

Meteoroid impacts cause craters and ejecta.

Tides are mostly due to the gravity of the Moon.

Solar and Lunar effects on Tides depend on the relative orientations of the Earth, Moon, and Sun

The tidal bulge is actually offset somewhat from being directly underneath the Moon. This produces a torque, a kind of twisting force on the Earth. The tides cause the Earth to slow down and the Moon’s orbit to increase in radius (4 cm per century). Also, the Moon’s rotation is synchronous with its orbit.

The Moon’s formation is believed to be due to a collision of a massive (Mars-sized) object with the early Earth. Computer simulation show that this could leave a moon-sized satellite in the correct orbit.

Lunar Evolution: the Moon after the early bombardment

Lunar Evolution: the formation of the maria by volcanic eruptions

Lunar Evolution: after 3 billion years of cratering