Astronomy Chapter 7
What unique features of Earth are important for life?
— Surface liquid water — Atmospheric oxygen — Plate tectonics — Climate stability
Why is Venus so hot?
— The runaway greenhouse effect made Venus too hot for liquid oceans. — All carbon dioxide remains in the atmosphere, leading to a huge greenhouse effect.
Is Venus geologically active?
- Its surface shows evidence of major volcanism and tectonics during the last billion years. - There is no evidence for erosion or plate tectonics.
The earthquakes that occur in Southern California generally occur above a
Fault
The large, roundish, low-elevation region in the southern hemisphere is called
Hellas Basin
Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a
Hot Spot
Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?
size
How many of the five terrestrial worlds are considered "geologically dead"?
two
Which of the following is a strong greenhouse gas?
water vapor
What geological features tell us that water once flowed on Mars?
— Dry riverbeds, eroded craters, and rock-strewn floodplains all show that water once flowed on Mars. — Mars today has ice, underground water ice, and perhaps pockets of underground liquid water.
What makes a planet habitable?
— Earth's distance from the Sun allows for liquid water on Earth's surface. — Earth's size allows it to retain an atmosphere and enough internal heat to drive geological activity.
Why did Mars change?
— Mars's atmosphere must have once been much thicker for its greenhouse effect to allow liquid water on the surface. — Somehow Mars lost most of its atmosphere, perhaps because of a declining magnetic field.
How does Earth's atmosphere affect the planet?
1. Erosion 2. Radiation protection 3. Greenhouse effect 4. makes the sky blue
What processes shape Earth's surface?
1. Impact cratering 2. Volcanism 3. Tectonics 4. Erosion
How is human activity changing our planet?
— Human activity is releasing carbon dioxide into Earth's atmosphere, increasing the greenhouse effect and producing global warming.
Larger planets are supposed to stay warm inside __________ than smaller planets.
Longer
Why is Earth geologically active?
We have a lot of internal heat & we are large enough to keep it
Scientists can estimate the age of a planetary surface by counting __________.
impact craters
Larger planets are also _______ able to retain atmospheres, making erosion more important there.
Better
The tallest mountain on Mars is called
Olympus Mons
Which describes our understanding of flowing water on Mars?
It was important once, but no longer.
Thus, these worlds experience volcanism and tectonics for much _____ than smaller worlds do.
Longer
Which heat source continues to contribute to Earth's internal heat?
Radioactive decay
found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.
Seafloor Crust
The slowly increasing distance between South America and Africa is due to
Seafloor Spreading
Layered ________ exposed by erosion can be seen when looking at the Grand Canyon in the United States.
Sedimentary Rock
The extremely deep ocean Marianas Trench is a result of
Subduction
high-elevation region dotted by tall volcanoes.
Tharis Bulge
Seismic studies on Earth reveal a "lost continent" that held great human cities just a few thousand years ago but is now buried beneath the Atlantic seafloor.
This is not plausible. Plates move only a few centimeters per year, so a continent could not be subducted in a few thousand years. Neither could erosional processes bury a continent on the time scale of human civilization.
The long, deep canyon running along the equator is called
Valles Marineris
Was there ever geological activity on the Moon or Mercury?
Yes both had some volcanism and tectonics when they were young.
In general, what kind of terrestrial planet would you expect to have the thickest lithosphere?
a small planet
Australia is composed of relatively old and thick
continental crust
