Astronomy last chapter
According to the fossil record, how old is the oldest evidence of life forms on the surface of the Earth?
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
absorbs ultra-violet light, preventing much of it from reaching the surface
Which of the following is a way we believe that the early atmosphere of the Earth differed from the atmosphere we have today?
all of the these
If no one has ever visited the core of the Earth, how do we know that it is made of metals?
circulating liquid metals in the core set up a large (measurable) magnetic field
Which part of the Earth has the greatest density?
core
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?
he early Earth must have been so hot it was like a liquid and heavier things sank to the middle
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 should you look for?
hydrogen
The largest part of the Earth is its
mantle
An important way that scientists have been able to study the interior of the Earth is by:
measuring how seismic waves are transmitted through the Earth
In terms of numbers, the most common life-forms on Earth are
microscopic creatures, too small to see with our eyes
The most abundant gas in the Earth's atmosphere is
nitrogen
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
According to the theory of plate tectonics,
slow motions within the mantle of the Earth move large sections of the crust around
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 region around the Earth where charged particles are trapped and spiral around is called:
the magnetosphere
The Drake Equation allows astronomers to estimate
the number of civilizations out among the stars with which we might communicate
The process of convection involves
the slow upward flow of warmer material and downward flow of cooler material
in which region of the Earth's atmosphere have you spent most of your life?
the troposphere
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
A spot where magma rises to the surface can be seen as 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?
water vapor and gases like carbon dioxide in the atmosphere cause a greenhouse effect
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
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
