Astronomy exam hw 4
What unique property of water allows ice to fracture mountains?
When water freezes to Ice it EXPANDS and can thus fracture rocks to form sheer cliffs and sharp rock formations in relatively new mountain ranges
Are mountains formed principally at rift zones or subduction zones?
Mountains are principally formed at subduction zones
Los Angeles, on the Pacific Plate, is moving toward the San Francisco on the North American Plate at a rate of 4 cm per year. San Francisco and Los Angeles are 600 km apart, how long will it take for LA to be in San Francisco
600 km/4 cm/yr = 600 km/ 4 x 10-5 km/yr = 1.5 x 107 yrs (15 million years)
What is the composition of the Earth's atmosphere?
78% Nitrogen, 21% Oxygen, 1% other
What two types of geologic processes can affect the structure of the surface of the Earth?
Endogenic - from inside the Earth; Exogenic - from outside of the Earth
What are the 5 types of planetary matter?
Fluid(gas), Ice, Rock, Metal, Plasma
In the Solar Nebulae theory what two conditions allowed a broadly distributed 'cloud' of gas matter to form into a rotating solar system?
Gravitational force causing the cloud to collapse, and conservation of angular momentum causing the cloud to speed up in rotation (from some infinitesimal initial rotation).
Are greenhouse gases transparent or absorbing in the infrared?
Greenhouse gases are not transparent in the infrared.
Hurricanes, tornadoes and cyclones are low-pressure areas. In which direction do they rotate in the northern hemisphere and why
Hurricanes, etc., rotate due to the Coriolis force resulting from the rotation of the Earth; they would rotate clockwise in the southern hemisphere, and counterclockwise in the northern hemisphere.
What is the believed composition of the earth's core, and why?
It is believed to be primarily Iron since iron is the most prevalent metallic element
Jupiter is approximately 5 times farther away from the sun than is the Earth, how much less radiation per unit area falls on Jupiter as compared to Earth?
Radiation/unit area 1/distance2; Earth rad/area = 1/12 = 1, Jupiter rad/area = 1/52 = 1/25
What technique has been used to define the internal structure of the Earth?
Seismography
What is the origin of igneous rock?
Solidification from molten state - volcanic
When do Spring Tides occur?
Spring Tides occur when the Moon and the sun are in line with the Earth.
What are the Aurora due to?
The Aurora are due to electrons precipitating down the Earth's magnetic field lines and colliding with air atoms causing them to emit radiation.
What is the origin of the Earth's magnetic field?
The Earth's magnetic filed is due to rotation of a conducting liquid (molten iron) in the core. generating an electric current which generates a magnetic field.
What is the Ring of Fire?
The Ring of Fire is the Pacific plate boundary along which multiple volcanoes are found.
In the Magnetosphere what are the Van Allen Belts?
The Van Allen Belts are captured electrons in donut orbits about the Earth (two specific donuts) held in place by the Earth's magnetic field.
If the density of rock is ~ 2.5 gm/cm3, what is the first clue that the Earth must have a dense (metallic) core?
The density of the Earth is ~ 5.5 g/cm3
