Astronomy Final HW 8-14
The lowest temperature in Earth's atmosphere is about
-80°C or 193K.
Since 1900, how much has the global temperature risen?
0.7°C
In the early solar nebula, iron sulfide condensed into solid form at a temperature of about 750 K. What is the smallest distance from the Sun at which this would have happened?
0.9 AU
Together, hydrogen and helium account for what percentage of the total mass of all matter in the universe?
98%
The age of Earth is considered to be
about 4.6 billion years
Various ices condense at temperatures less than 300K. What is the smallest distance from the Sun in the early solar nebula at which these ices would have condensed to form solid particles?
2 AU
Our solar system seems to have formed about how long ago?
5 billion years
Earth has an average density of
5.5 times that of water.
What protects us from the damaging radiation effects of the high-speed solar wind that flows through interplanetary space?
Earth's magnetic field
The planet whose atmosphere is composed primarily of nitrogen is
Earth.
How has the present mix of chemical elements in the universe been produced?
H and some He were formed in the Big Bang, while the heavier elements have been slowly formed in the centers of stars over the life of the universe.
What is surprising about the planet orbiting the star 51 Pegasi?
It has a mass almost as large as Jupiter, but its orbital radius is smaller than that of Mercury.
In a rotating physical system (e.g., a star formation region, or a skater), what happens to the rotation rate (or angular speed) when the mass of the system condenses toward the center of rotation?
It increases.
One of the major differences between Earth and its neighboring planets, Venus and Mars, is the lack of large quantities of CO2 in its atmosphere. If all three planets were originally formed with significant quantities of this gas in their atmospheres, where is the majority of this CO2 on Earth at the present time?
It is locked up in carbonate, and carbon rich rocks and minerals formed in these and on Earth's surface.
Which one of the following statements about the solar wind is true?
Its particles travel at very high speeds.
The idea that the Sun and planets formed from a large cloud of gas and dust was first proposed by
Kant and Laplace.
What is surprising about the extra solar planets that have been discovered?
Many of them giant planets like Jupiter, orbiting at distances characteristic of terrestrial planets.
Suppose Earth was put into orbit around a cool star (cooler than our Sun) at the right distance for our oceans to remain liquid so that life could still exist but the star emitted no UV radiation. Each of the following statements gives a consequence of this change, except one. Which would not be a consequence of this change?
Our magnetosphere would disappear.
Photosynthesis is a chemical process which takes place in green plants. What is its effect on our atmosphere?
Photosynthesis is consumes carbon dioxide from our atmosphere and produces oxygen.
The most probable time sequence for the solar system's formation was that the
Sun contracted first as a gas ball ,and the planets and moons formed shortly afterward by accretion and condensation.
We have found that the upper layers of the mantle are "plastic." Why is this important?
The continents are able to float and drift on these layers.
A theory of the origin of the solar system must take into account all important general properties of the planets. These include three of the four properties listed below. Which one is not an important general property of the planets?
The magnetic fields of the planets are produced by a variety of mechanisms.
Why do transverse seismic S waves not traverse Earth's deep interior?
They cannot travel through the liquid part of the core.
An early theory of solar system formation was the tidal hypothesis - the idea that a star passed close enough to the Sun to draw out a long filament of material which then condensed to form the planets and other solar system bodies. Why was this theory discredited?
Tidal forces strong enough to pull a filament out of the Sun would also be strong enough to cause it to disperse before it could condense into planets.
The green house effect is the
absorption by atmospheric gases of infrared radiation emitted by a planet that has been heated by solar visible and ultraviolet radiation.
Which of the following roles played by the massive rain forests of Earth is perhaps the most important in the maintenance of the entire world's living environment?
absorption of CO2 and production of O2, renewing our atmosphere and reducing the greenhouse effect
The large amount of free oxygen in Earth's present atmosphere is primarily a result of
a biological process such as photosynthesis.
The material from which our solar system formed is believed to be
a cold, dark cloud of gas and dust.
Ozone is
a molecule made of three oxygen atoms.
What is the astrometric method used in searches for planets orbiting stars other than the Sun?
a search for tiny wobbles in the position of the star due to the gravitational pull of a planet orbiting around it
The Oort cloud is
a spherical solar system of icy objects far beyond the orbit of Pluto.
The formation of terrestrial-type planets around a star is most likely to have occurred by what process?
accretion, or slow accumulation of smaller particles by mutual gravitational attraction
The outer core of Earth is molten, but the inner core is solid. The reason for this is that the
actual temperature is below the melting point of the core material at the high pressure of the interior.
A "Slinky" toy is made up of a long flexible spring. The analogous wave to primary wave produced in an earthquake would be generated by moving the end of the spring
back and forth in a direction along the spring.
Where is the mantle of Earth located?
between core and crust.
So far, what is the typical mass of the majority of extra solar planets discovered?
between the mass of Saturn and a few times the mass of Jupiter
According to modern theories, the most significant difference between the formation of the terrestrial and Jovian planets is that
both formed by accretion of planetesimals, but the Jovian planets became massive enough to attract gas onto them directly from the solar nebula.
Which of the following molecular species plays a major role in the greenhouse effect in planetary atmospheres?
carbon dioxide.
Where in the universe are heavy elements with masses greater than that of helium being produced at this time?
central cores of stars
Auroras, or northern and southern lights, are caused by
charged particles from the magnetosphere, striking atoms in the upper atmosphere and causing the gases to emit light.
"Continental drift" on Earth is now thought to be caused by
circulation currents in the deep interior causing slabs of Earth's crust to move slowly.
The age of the solar system has been dated rather precisely to 4.56 billion years. What method was used to determine this number?
determining the age of meteorites by radioactive dating
The point on Earth's surface directly above an earthquake is known as its
epicenter.
If a large cloud of gas and dust is initially rotating, and it begins to contract without losing any mass, it will rotate
faster.
The most probable theory for the solar system's formation is
gas and dust clouds condensed to form the Sun, while planets formed later within a nebular disk.
You are a geologist detecting S (secondary) seismic waves from a source somewhere else on Earth. You know that these S waves
have not passed through the center of Earth.
At the present time, how many extra-solar planets have had confirmed discoveries?
hundreds
The most common elements in the universe are
hydrogen, smaller quantities of helium, and very small quantities of heavier elements.
The most abundant material in the universe is
hydrogen.
The birth place of the Sun and planets (and of other stars and maybe their planets) is thought to have been
in cool gas and dust clouds.
Terrestrial planets are thought to have dense iron cores because
in earlier molten states the heavy elements sank and lighter materials floated to the surface by chemical differentiation.
The oldest rocks, as measured by radioactive age-dating, have been found
in meteorites.
What is the direct source of the energy which warms the lowest layers of our atmosphere?
infrared radiation from the ground
The greenhouse effect heats a planet because
infrared radiation is trapped.
The magnetic field of Earth
is related to its rotation around its axis.
The temperature in the stratosphere increases with increasing altitude because
it is heated by the absorption of solar ultraviolet radiation by ozone.
Sedimentary rocks are found
just about everywhere on Earth's surface.
The long and high mountain ranges found in the centers of several major oceans on Earth, such as the Mid-Atlantic Ridge, are caused by
lava upflow as the tectonic plates on the seafloor split apart and separate.
One distinct difference between Earth and its neighboring planets, Venus and Mars, is the presence of
liquid water on its surface and water molecules chemically locked into rocks.
Which of the following is not a region of Earth's atmosphere?
magnetosphere
Sedimentary rocks commonly form from
minerals precipitating out of the oceans and accumulating on the ocean bottom.
If you were able to measure Earth's magnetic field at sometime, say, 100,000 to 200,000 years ago, you would
most likely find the field to be quite different in magnitude from what it is today.
Earth is the only planet whose atmosphere contains a significant amount of
oxygen.
Astrometry is the branch of astronomy dealing with the measurement of the
precise positions of stars and galaxies.
What name is given to the concentration of mass that formed at the center of the solar nebula, eventually becoming the Sun?
protosun
Which of the following areas of human endeavor and development is having the most impact on Earth at the present moment?
rapid increase in human population
The albedo of a planet is the fraction of energy that is
reflected by the whole planet, including atmosphere and surface.
Earth's magnetosphere is the
region beyond the atmosphere, where the magnetic field protects us from solar wind.
The Van Allen belts are
regions of high-energy charged particles trapped within Earth's magnetosphere.
Which of the following types of material has the highest condensation temperature in the planetary system?
rocks and dust grains
The three common substances believed to have been important in planet formation are
rocks, ices, and gases
The waves that geologists and geophysicists use to probe the inside of Earth are
seismic waves.
We need the ozone layer because it
shields us from harmful solar ultraviolet radiation.
Earth's magnetic field originates in
slowly moving currents of molten iron which produce electric currents in the deep interior of Earth.
Which of the following is the major power source that drives the dynamics of Earth's atmosphere?
solar radiation
What is the basic structure of Earth's interior?
solid iron inner core, molten iron outer core, rocky mantle, lighter rocky crust
In which layer of Earth's atmosphere is the ozone layer located?
stratosphere
Which of the following techniques is used by geologists and geophysicists to probe the structure of Earth's core and mantle?
study of the deflection of seismic waves produced by earthquakes
More than any other, which physical parameter probably controlled the early evolution of the planetary system and dictated the characteristics of the planets that eventually formed?
temperature distribution within the nebula
In order for the disk instability model to be able to account for the formation of the Jovian planets
the gas in the nebular disk would have to be clumpy rather than smooth.
The surface temperature of Earth is actually warmer than expected from the amount of sunlight received. This is a result of
the greenhouse effect.
The reason for the vast amount of hydrogen in the interior of Jupiter is probably that
the mass of the initial condensation of rocks at Jupiter's orbit was sufficient to attract vast amounts of gas to it.
The temperature began to rise at the center of the solar nebula because
the nebula was contracting, increasing the speed of motion of the atoms.
Earth's interior received its heat energy from the impacts of planetesimals and from radioactivity. This heat energy is gradually radiating into space. As Earth's interior continues to cool, we can expect that, in the distant future,
the outer core will become solid like the inner core.
All the boundaries of the major moving tectonic plates on Earth's surface coincide with
the positions of maximum earthquake occurrence.
Each of the following contributes substantially to changes in the temperature of Earth's surface, except one. Which is the exception?
the size of the hole in the ozone layer
The lowest pressure in Earth's atmosphere occurs where?
the upper thermosphere
The hottest part of Earth's atmosphere is
the upper thermosphere.
The protosun became a full fledged star when
thermonuclear fusion reactions began at its center.
In which layer of Earth's atmosphere does all weather occur?
troposphere
The major layers of Earth's atmosphere from the surface upward in correct order are
troposphere, stratosphere, mesosphere, thermosphere.
The Mid-Atlantic Ridge in Earth's crust is a region where
two tectonic plates are slowly spreading apart.
The San Andreas fault in California is an example of
two tectonic plates sliding past each other.
The Mid-Atlantic Ridge is being produced by
volcanic upflow pushing two tectonic plates apart.
Suppose that an astronaut trained in geology lands on the surface of a distant planet and finds that most of the rock at the landing site is composed of limestone. The astronaut can immediately surmise that the location of the landing site
was once the bed of an ancient ocean.
Which substances form ice in the outer solar system?
water, ammonia, methane
Most earthquakes occur
where crustal plates are colliding, separating or sliding past each other.