Astronomy Ch.8 and 30

The region around the Earth where charged particles are trapped and spiral around is called:

a. the magnetosphere

The process of convection involves

a. the slow upward flow of warmer material and downward flow of cooler material

Which of the following is a way we believe that the early atmosphere of the Earth differed from the atmosphere we have today?

a. there was little if any free oxygen early on b. there was no ozone layer early on c. there was probably more carbon dioxide early on than there is today d. all of the above

A spot where magma rises to the surface can be seen as a

a. volcano

The average temperature on planet Earth is higher than you would expect just from the heating of sunlight alone. What is the explanation for this?

b. carbon dioxide (and other gases) in the atmosphere cause a greenhouse effect

4. If no one has ever visited the core of the Earth, how do we know that it is made of metals?

b. circulating liquid metals in the core set up a large (measurable) magnetic field

he largest part of the Earth is its

c. mantle

In terms of numbers, the most common life-forms on Earth are

c. microscopic creatures, too small to see with our eyes

Scientists now understand that the Earth consists of layers, with the densest materials in the core. What allowed the differentiation of the Earth's layers to happen?

c. the early Earth must have been so hot it was like a liquid and heavier things sank to the middle

In which region of the Earth's atmosphere have you spent most of your life?

c. the troposphere

According to the fossil record, how old is the oldest evidence of life forms on the surface of the Earth?

d. about 3.5 billion years

One way in which the ozone layer is useful for life forms on the Earth's surface is that it

d. absorbs ultra-violet light, preventing much of it from reaching the surface

3. Which part of the Earth has the greatest density?

d. core

An important way that scientists have been able to study the interior of the Earth is by:

d. measuring how seismic waves are transmitted through the Earth

The most abundant gas in the Earth's atmosphere is

e. nitrogen

According to the theory of plate tectonics,

e. slow motions within the mantle of the Earth move large sections of the crust around

If you wanted to find a type of atom in your little finger that has been in its present form (been the same element) since the beginning of the universe, which element would you look for

hydrogen

In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization?

no, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etC.) that we believe are necessary to start life as we know it

Which band of the electromagnetic spectrum do astronomers suggest is likely to be the best (cheap, little competition from nature, penetrates atmospheres) for communication between civilizations around different stars?

radio waves

In 1980, scientists suggested that the great mass extinction of 65 million years ago (which ended the reign of dinosaurs) may have been caused by a large impact from space. What discovery gives a big boost to this idea?

the discovery of a buried crater (about 200 km across) near Chicxulub, Mexico

the number of civilizations out among the stars with which we might communicate

the number of civilizations out among the stars with which we might communicate

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is

the speed of light

Which of these did the June 1908 impact event in Siberia and the 2013 event in the Russian city of Chelyabinsk have in common?

they both exploded high in the atmosphere and produced a shock wave that reached the ground

From a scientific perspective, which of the following statements about life elsewhere in the universe is best supported by current evidence?

while we have evidence of the building blocks of life elsewhere in the universe, we have no definite evidence about life around other stars at this time