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Astronomy Chapters 5-10
Chapters 5-10 Astronomy for HCC
110
Astronomy
Undergraduate 1
03/29/2014
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Term
5. Fusion is the process by which
 Definition
elements are transformed into heavier elements by nuclear reactions.
Term
5. A curious fact about the structure of the planet Jupiter, compared with the structure of Earth, is that it has
 Definition
much greater mass but much lower average density.
Term
5. The most probable theory for the formation of the solar system is
 Definition
the condensation of a nebula of hot gas into the Sun and planets.
Term
5. the condensation of a nebula of hot gas into the Sun and planets.
 Definition
Many of the extrasolar planets are giant planets like Jupiter, orbiting at distances characteristic of terrestrial planets like Earth, where giant planets cannot form.
Term
5. The albedo of Mercury is about 0.1. This means that
 Definition
Mercury reflects 1/10 of the sunlight falling on it.
Term
5. The albedo of Mercury is about 0.1. This means that
 Definition
Mercury reflects 1/10 of the sunlight falling on it.
Term
5. What was the material from which the solar system formed?
 Definition
nebula made mostly of hydrogen and helium gas but enriched in heavier elements from supernova explosions
Term
5. Where was all the hydrogen in the universe formed?
 Definition
in the Big Bang, at the very beginning of the universe
Term
5. The manner in which the terrestrial planets formed was the
 Definition
accretion of solid planetesimals containing mostly rocky material.
Term
5. The overall shape of the orbits of most of the planets in the solar system is
 Definition
slightly elliptical, but nearly circular.
Term
5. What is the basic difference between comets and asteroids?
 Definition
Comets are mostly composed of ices, whereas asteroids are mainly composed of rocks.
Term
5. The average density of a planet is
 Definition
its total mass divided by its total volume.
Term
5. In our solar system, which of the following planets is NOT a member of the terrestrial group?
 Definition
Jupiter
Term
5. How do we measure the mass of an extrasolar planet?
 Definition
We use Newton’s law of gravity, using the measured distance of the planet from its star and the planet’s gravitational pull on the star
Term
5. In the search for planets around other stars, which of the following possible lines of evidence has NOT yet been seen?
 Definition
faint pinpoints of light slowly circling a star
Term
5. Which planet in our solar system has the largest mass?
 Definition
Jupiter
Term
6. Most of the mountain ranges on the Moon are the
 Definition
circular edges and rims of large maria that have been formed by impacts from large objects.
Term
6. Earth’s magnetic field is most probably generated by
 Definition
electric currents in Earth’s electricity-conducting molten core.
Term
6. How was the Mid-Atlantic Ridge formed?
 Definition
Molten rock pushed up from Earth’s interior and forced two crustal plates apart.
Term
6. What process created the lunar regolith?
 Definition
cracking and pulverizing by meteoric bombardment
Term
6. Craters are not apparent on Earth at the present time in the abundance seen on the Moon because
 Definition
plate tectonics has returned cratered surface layers into Earth’s interior, and weathering has obliterated the more recent craters.
Term
6. Subduction on Earth is the process by which
 Definition
dense material sank while lighter material rose to the surface during the early geological history of Earth.
Term
6. What is the most likely cause of the smooth and relatively crater-free surfaces of lunar maria?
 Definition
The lava in these basins flowed in the relatively late geological history of the Moon, after the period of major bombardment.
Term
6. What is a typical speed of drift for a continent sliding over Earth’s surface?
 Definition
a few centimeters per year
Term
6. Lunar rilles are
 Definition
meandering, canyonlike valleys.
Term
6. Which of the following mechanisms is most likely to have taken place while Earth was molten to form the present structure of Earth?
 Definition
Heavy elements sank to the center under gravity while lighter materials rose to the surface and solidified into rocks.
Term
6. Which of the following observations have been made about the Moon that will be very helpful (if they prove true) as humans begin to plan for its colonization?
 Definition
discovery of evidence of water (as ice) that can be used for the support of life, the growth of food, and as fuel if it is split into hydrogen and oxygen by sunlight
Term
6. What is the basic structure of Earth’s interior?
 Definition
solid iron inner core, molten iron outer core, rocky mantle, lighter rocky crust
Term
6. Why does the temperature in the stratosphere increase with increasing altitude?
 Definition
The stratosphere is heated by solar ultraviolet radiation absorbed by the ozone layer.
Term
6. In its orbit around Earth, the Moon
 Definition
keeps the same side toward Earth.
Term
6. Where did the majority of the large amount of carbon dioxide (CO2) from the second major atmosphere to form on the early Earth end up?
 Definition
still in the atmosphere, but the quantity of nitrogen and oxygen has since risen to make these constituents the most abundant and relegate carbon dioxide to a minor constituent
Term
6. The Moon rotates synchronously as it orbits Earth, always keeping one side pointed toward Earth, because
 Definition
of the effect of the gravitational pull of Earth on the tidally induced bulge on the Moon.
Term
6. If Earth is known to have an average albedo of 0.37, what percentage of the sunlight hitting Earth is absorbed by it?
 Definition
63%
Term
6. The troposphere of Earth is the
 Definition
atmospheric layer closest to the ground.
Term
6. Which of the following theories is now considered to be the most likely for the formation of the Moon?
 Definition
collision-ejection theory, where an interplanetary collision knocked material into orbit around Earth that eventually formed into the present-day Moon
Term
6. Auroras on Earth are caused by
 Definition
high-energy charged particles from the magnetosphere guided by Earth’s magnetic field into polar regions of the atmosphere.
Term
The two conditions that appear to be necessary for the generation of a powerful magnetic field in planets that are NOT present simultaneously on Mercury are
 Definition
rapid rotation and a molten iron core.
Term
“This planet has a large iron core, a heavily cratered surface, and no atmosphere.†Which planet in our solar system fits this description?
 Definition
Mercury
Term
Which of the following statements best describes our current understanding of the Valles Marineris?
 Definition
The valley system formed primarily by cracking and faulting of the Martian surface, but some valleys at the eastern end appear to have been carved by water.
Term
The conditions on the surface of Venus are
 Definition
a high-pressure, high-temperature, carbon dioxide atmosphere.
Term
What significant evidence is there for the idea that large quantities of water once flowed on the planet Mars?
 Definition
deep, winding canyons and flood plains
Term
The moons of Mars are
 Definition
irregularly shaped, cratered, and grooved.
Term
Why has Mercury become locked into a 3-to-2 spin orbit coupling instead of a 1-to-1 coupling like the Moon around the Earth?
 Definition
Mercury’s orbit is very eccentric, so its orbital speed varies while its rotation rate remains constant, preventing a 1-to-1 lock.
Term
The severe atmospheric conditions that quickly destroyed spacecraft that soft-landed on the surface of Venus were
 Definition
high temperatures, high pressures, and corrosive acid clouds and mist.
Term
What is the principal reason we have no volcanoes on the Earth anywhere near the size of Olympus Mons?
 Definition
Because of tectonic activity on the Earth, a volcano does not sit over the same spot for long periods and continue to grow.
Term
Temperatures on the surface of Mercury are seen to fluctuate between very cold 100 K (–173°C) and extremely hot 700 K (427°C). What does this measurement indicate about conditions on Mercury?
 Definition
The planet is close to the Sun, has no atmosphere to maintain heat from the Sun, and is rotating.
Term
In view of the present surface and atmospheric conditions on Mars, why would there be no liquid water on its surface?
 Definition
The very low atmospheric pressure would allow the water to boil and evaporate rapidly.
Term
The reason that very few impact craters are seen on Venus compared with the Moon is believed to be that
 Definition
lava flows and surface melting have covered all but the most recent craters.
Term
Venus has
 Definition
no magnetic field.
Term
What is the main reason that the greenhouse effect has been much more effective in raising the surface temperature on Venus than in raising the surface temperature on the Earth?
 Definition
Carbon dioxide, which traps heat from the planet’s surface, is the major component in the very dense Venusian atmosphere, while it is a only a minor constituent of the Earth’s.
Term
7. How have we obtained samples of Martian rocks?
 Definition
Rocks were blasted off Mars by impacts and landed on Earth as meteorites.
Term
7. Mercurys iron core takes up approximately what fraction of the volume of the planet?
 Definition
about 40%
Term
7. What is the Caloris Basin?
 Definition
multiringed impact basin on Mercury
Term
7. There are many reasons why a multiday hiking trip on foot through the Valles Marineris on Mars would not be advisable, at least not without suitable protection. Which of the following conditions would NOT be a concern?
 Definition
oppressively high atmospheric pressure
Term
7. The Martian magnetic field is
 Definition
weak and localized, not at all like the global magnetic field of the Earth.
Term
8. Triton, the giant moon of Neptune, differs from all other major moons of the planets because
 Definition
it orbits in a retrograde direction, opposite to the planets rotation.
Term
8. Which planetary satellites are known to have plumes of gas escaping through their surfaces?
 Definition
Io and Triton
Term
8. Jupiters mass makes up what fraction of the total mass of the planetary system, excluding the Sun?
 Definition
70%
Term
8. How was Neptune discovered?
 Definition
by a careful application of Newtons laws to the somewhat irregular motions of Uranus
Term
8. One interesting feature of Jupiters rotation is the fact that
 Definition
regions of Jupiter at different latitudes appear to rotate at different rates.
Term
8. The specific and unique property of water that was responsible for the large-scale surface features dark polygons surrounded by heavily grooved and lighter terrain”on Ganymedes surface is
 Definition
the fact that it expands when it freezes. Water squeezed out from beneath old, dark ice expanded to produce the lighter, raised terrain
Term
8. Which planetary satellite shows strong evidence of disruption by an impact at some time in its history and of subsequent partial reassembly and reshaping by self-gravity?
 Definition
Miranda
Term
8. The major gaps in the rings of Saturn are most likely to be caused by
 Definition
combined gravitational forces from Saturn and its moons that deflect the paths of particles that stray into the gaps.
Term
8. The requirement(s) for the generation of a powerful magnetic field in a Jovian planet (e.g., Jupiter, Saturn) appear(s) to be a
 Definition
liquid metal interior and relatively rapid rotation.
Term
8. The Roche limit around a planet is defined as the
 Definition
distance at which a planet creates tides on its moons surface high enough to pull its moon apart.
Term
8. Neptunes high cirrus clouds consist of
 Definition
methane ice crystals.
Term
8. Which characteristic of Jupiters satellite Io makes it different from 8. any other known satellite in the solar system?
 Definition
Io is volcanically active, with gas plumes and lava flows.
Term
8. The ocean water that is predicted to occur below the surface of Jupiters moon Europa is kept unfrozen by heat from
 Definition
tidal distortions of the moon by the combined gravity of Jupiter and the other moons.
Term
8. The surface of Callisto, the outer Galilean moon of Jupiter, can best be described as
 Definition
relatively smooth, with a great many impact craters and one large basin created by an asteroid impact.
Term
8. What causes the banded structure on Jupiters visible surface as seen from the Earth?
 Definition
breaking up by underlying mountain ranges of the strong eastward flow caused by Jupiters rapid rotation
Term
8. What characteristic of Saturns satellite Titan makes it different from any other known satellite in the solar system?
 Definition
Titan has a permanent and dense atmosphere.
Term
8. What gives Uranus its blue-green coloration?
 Definition
absorption of red light by methane gas
Term
8. The internal structure of the two largest Jovian planets (from the center outward) is a(n)
 Definition
rocky core, a liquid “ice†layer, a liquid metallic hydrogen and helium layer, and an ordinary hydrogen and helium gaseous layer.
Term
8. Saturn is less massive than Jupiter but almost the same size. Explain.
 Definition
The smaller mass exerts less gravitational force and is unable to compress the mass as much as in Jupiter.
Term
8. Which of the following effects is now thought to be the most likely cause for the inclinations of spin axis of several of the planets such as Uranus (and even the Earth) to their orbital planes?
 Definition
major collision with another planetlike body
Term
9. How large does the coma, or gas cloud surrounding a comet nucleus, become when it reaches its closest point to the Sun?
 Definition
about 106 km, as big as the Sun
Term
9. Most of the asteroids of the solar system move around the Sun between the orbits of which planets?
 Definition
Mars and Jupiter
Term
9. The Kuiper belt is
 Definition
a flat or donut-shaped distribution of distant comets around the Sun, extending out about 500 AU.
Term
9. What mechanism controls the direction in which a comets ion tail is aligned in space?
 Definition
flow of solar wind past the comets head
Term
9. What is the typical distance between asteroids in the asteroid belt?
 Definition
10 million km
Term
9. A piece of rock from outer space that reaches Earth’s surface after surviving a fiery passage through Earths atmosphere is known as a(n)
 Definition
meteorite
Term
9. Stony iron meteorites are believed to
 Definition
originate from differentiated asteroids (in which iron sank to the center).
Term
9. What is considered to be the most likely origin of the comets in the Oort cloud?
 Definition
The comets in the Oort cloud formed near the orbits of Uranus and Neptune and were flung outward by the gravitational influence of these two planets.
Term
9. If you were standing on Pluto, how often would you see the satellite Charon rise above the horizon each day?
 Definition
once every 2 days because Charon orbits in the same direction Pluto rotates but more slowly
Term
9. A shooting star is a
 Definition
small particle of interplanetary dust burning up and glowing as it enters Earths atmosphere.
Term
9. The Allende meteorite contained an abundance of 26Mg, an isotope of magnesium. What is the significance?
 Definition
26Mg is the stable product of the decay of radioactive 26Al. The 26Al from which the 26Mg formed was probably produced in a nearby supernova explosion about the time the solar system was formed.
Term
9. The cause of the meteor showers seen at regular times each year on Earth is most probably
 Definition
Earth moving through the remnant dust and rock fragments of an old comet that are orbiting the Sun in the comets old orbit.
Term
9. Stony meteorites
 Definition
are very much like ordinary silicate rocks.
Term
9. The most likely origin of the dirty snowballs that become comets when they are deflected into orbits that bring them closer to the Sun is the
 Definition
Kuiper belt and Oort cloud surrounding the solar system.
Term
9. Interplanetary material
 Definition
falls on Earth at the rate of several hundred tons per day, mostly as micrometeoroids.
Term
10. The order of the layers or parts of the Sun, as radius increases, is
 Definition
radiative zone, convection zone, photosphere, chromosphere, corona.
Term
10. The temperature of the Sun’s photosphere is
 Definition
5800 K.
Term
10. The major feature that distinguishes a sunspot from other regions on the Sun is
 Definition
its very powerful magnetic field.
Term
10. One particular feature of the solar corona is its
 Definition
very high temperature.
Term
10. Which occurrence led astronomers to the conclusion that the temperature of the gases in the solar corona was very high?
 Definition
detection of emission lines from highly ionized elements like iron
Term
10. Spectral lines observed in the granules seen at the center of the Sun’s disk are
 Definition
blueshifted near the center of the granule and redshifted near the edge of the granule.
Term
10. In the thermonuclear process that is thought to heat the Sun, the nuclei of which chemical elements are converted to other nuclei to produce the requisite energy?
 Definition
Hydrogen is converted to helium.
Term
10. Any object will collapse under its own weight unless something stops it. In an ordinary star like the Sun, this collapse is prevented by
 Definition
gas pressure inside the star.
Term
10. What is the cause of the sunspot cycle on the Sun?
 Definition
Subsurface magnetic fields are twisted by the Sun’s differential rotation and break through the surface as sunspots, then gradually cancel each other and return below the surface.
Term
10. How does the number of sunspots on the Sun vary with time?
 Definition
The number of sunspots varies relatively regularly, with a period of about 11 years.
Term
10. Recent solar neutrino experiments have confirmed the suspicion that the explanation for the apparent shortfall in neutrino detection rates over the last 30 years is that
 Definition
2/3 of the solar neutrinos transform into types of neutrinos that were undetectable by old detection techniques.
Term
10. The strength of the magnetic field in a sunspot is estimated from Earth by
 Definition
observing the wavelength splitting of atomic spectral lines by the Zeeman effect.
Term
10. Where would you expect to find spicules?
 Definition
as small but rapidly erupting gas jets in the atmosphere of the Sun
Term
10. The solar wind is made up primarily of
 Definition
hydrogen nuclei and electrons, some He nuclei.
Term
10. Apart from the helium nuclei and energy that are produced in proton-proton reactions in the Sun’s core, what are the other by-products?
 Definition
positive electrons (positrons), gamma rays, and neutrinos
Term
10. In what fundamental way does the overall solar magnetic field differ from that of Earth?
 Definition
The solar field lies just beneath the surface, while Earth’s field passes through the whole Earth.
Term
10. Coronal holes are thought to be the source of
 Definition
the solar wind.
Term
10. The word chromosphere refers to a
 Definition
layer in the Sun’s atmosphere.
Term
10. Over the course of a sunspot cycle of about 11 years, the regions of sunspot occurrence on the Sun move
 Definition
equatorward, moving from 30° to 10° latitude.
Term
10. If a solar flare produces an X-ray outburst and also triggers a coronal mass ejection (CME), what will be the arrival times of these components, referenced to the time of occurrence on the Sun?
 Definition
The X rays arrive about 8 minutes after the flare, while the CME material arrives after about 2 days.
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