Exam 2 Astro
(a)The planet discovered orbiting a star, 59 light-years from Earth, moves in an orbit with semimajor axis 0.54 AU and eccentricity 0.43. The period of the orbit is 105.8 days. Find the mass of the star. (Hint: The planet has far less mass than the star.) 3.73e30 kg (b) Compare your answer with the mass of the Sun. 1.87 solar masses
(a) 3.73e30 kg F=G m1m2/R^2 P^2=[4pi^2/G(m1+m2)]a^3 m1 +m2= 4pi^2a^3/GP^2 G=6.67 x 10^-11 m1 + m2= (b) 1.87 solar masses mass of the sun is 1.9891 x 10^30 kg
(a) How does our current understanding of the formation of the solar system account for the observation that all planetary orbits lie in nearly the same plane? 1. A rotating disk of material, like the solar nebula, tends to flatten out and become planar. 2. As the early Sun rotated, instabilities tended to develop along the equator—where the rotation was fastest. The materials that later became the solar system were spewed out through these instabilities, in the equatorial plane of the Sun. (b) How does our current understanding of the formation of the solar system account for the observation that all planetary orbits are nearly circular? 1. Planetary orbits are nearly circular because noncircular orbits would be unstable due to gravitational perturbations from other solar-system objects. 2. Planetary orbits are nearly circular because planets in non-circular orbits have peak velocities, which are large enough to allow the planet to escape from the solar system. (c) How does our current understanding of the formation of the solar system account for the observation that all the planets orbit the Sun in the same direction the Sun itself rotates? 1. The counterclockwise orbital motion of the planets and the counterclockwise rotation of the Sun descended from the original counterclockwise rotation of the solar nebula. 2. The original solar rotation caused instabilities to form along the equator, and the material spewed out through these instabilities—which later became the planets—continued to rotate in the same direction as the Sun.
(a) A rotating disk of material, like the solar nebula, tends to flatten out and become planar. (b) Planetary orbits are nearly circular because noncircular orbits would be unstable due to gravitational perturbations from other solar-system objects. (c) The counterclockwise orbital motion of the planets and the counterclockwise rotation of the Sun descended from the original counterclockwise rotation of the solar nebula.
(a) What is meant by accretion? 1. As a planet moves around the Sun, it collides with the residual gas and dust in its orbit. The gas and dust stick to the planet and increase its mass. This is accretion. 2. Accretion is the process in which an object gathers smaller bits of matter to itself through gravitational attraction. (b) Why are the terrestrial planets denser at their centers than at their surfaces? 1. When these planets were molten in the early solar system, the denser, iron-rich minerals sank to the centers of the planets, whereas the less dense, silicon-rich minerals floated to their surfaces. 2. The terrestrial planets formed gradually as the early Sun cooled, and thus are differentiated with respect to condensation temperatures. First, the cores of the planets formed from dense iron-rich materials with high condensation temperatures. Then, as the Sun cooled, less dense silicon-rich materials with lower condensation temperatures condensed out of the solar nebula and were added to the terrestrial planets by accretion.
(a) Accretion is the process in which an object gathers smaller bits of matter to itself through gravitational attraction. (b) When these planets were molten in the early solar system, the denser, iron-rich minerals sank to the centers of the planets, whereas the less dense, silicon-rich minerals floated to their surfaces.
(a) What is a planetesimal? 1. A planetesimal is a small planet-like object, like Ceres or Pluto, too small to be classified as a planet. 2. Planetesimals are asteroid-like bodies with diameters of a kilometer or so. (b) How did planetesimals give rise to the terrestrial planets? 1. Collisions between planetesimals generated heat, which welded the planetesimals together to form the terrestrial planets. 2. The early solar system was filled with rock and dust. These were attracted gravitationally to the planetesimals, causing them to grow into terrestrial planets.
(a) Planetesimals are asteroid-like bodies with diameters of a kilometer or so. (b) Collisions between planetesimals generated heat, which welded the planetesimals together to form the terrestrial planets.
The figure below shows that carbon, nitrogen, and oxygen are the most abundant elements (after hydrogen and helium). In our solar system, the atoms of these elements are found primarily in the molecules CH4 (methane), NH3 (ammonia), and H2O (water). Why is this? 1. Hydrogen is the most abundant element and is chemically reactive. Carbon, nitrogen, and oxygen are abundant and chemically reactive, so it is not surprising that compounds of these elements with hydrogen are also abundant. 2. Hydrogen has a single valence electron, but carbon needs four, nitrogen three, and oxygen two. So, these are the only combinations of these elements that can be formed.
. Hydrogen is the most abundant element and is chemically reactive. Carbon, nitrogen, and oxygen are abundant and chemically reactive, so it is not surprising that compounds of these elements with hydrogen are also abundant.
Why should solar flares and coronal mass ejections be a concern for businesses that use telecommunication satellites? 1. Solar flares eject large numbers of particles into Earth's atmosphere. This heats the atmosphere and causes it to expand. This expansion produces additional atmospheric drag on satellites and can slow them and cause them to fall back to Earth. 2. Telecommunication satellites could be damaged by the flux of particles from flares or coronal mass ejections. Solid-state electronic devices are particularly vulnerable.
. Telecommunication satellites could be damaged by the flux of particles from flares or coronal mass ejections. Solid-state electronic devices are particularly vulnerable.
Mercury distance from the Sun
.4 AU
Venus distance from the Sun
.7 AU
Earth distance from the sun
1 AU
Mars distance from the Sun
1.5 AU
The distance from the asteroid 433 Eros (see the figure below) to the Sun varies between 1.13 and 1.78 AU. What is the period of Eros' orbit? 1. The period varies between 1.20 and 2.37 years. 2. 1.76 years 3. 3.57 years
1.76 years
Saturn distance from the Sun
10 AU
How do astronomers know that the temperature of the corona is so high? 1. Spacecraft orbiting the Sun have passed through the corona and have made direct temperature measurements before burning up. 2. Astronomers know that the temperature of the corona is so high because they see spectral lines of highly ionized atoms that can exist only at those high temperatures. 3. Some comets have passed through the Sun's corona. By monitoring the rate at which the nucleus vaporizes and the coma grows, a good estimate of the temperature can be obtained.
2. Astronomers know that the temperature of the corona is so high because they see spectral lines of highly ionized atoms that can exist only at those high temperatures.
Three-quarters of the radioactive potassium (40K) originally contained in a certain volcanic rock has decayed into argon (40Ar). How long ago did this rock form? 1. 1.3 billion years 2. 2.6 billion years 3. 975 million years
2.6 billion years
Uranus distance from the Sun
20 AU
Scientists realized that the Sun's energy cannot be due to gravitational contraction because the Sun would only last for
20 million years
Einstein's equation, which determines the amount of energy created from a given amount of mass, is given by which of the following? 1. E = mc 2. E = m^2c 3. E = mc^2 4. E = m^3c
3. E = mc^2
Neptune distance from the Sun
30 AU
Which of the following equations correctly depicts the by-products of the proton-proton cycle? a) 4 protons → 4He + 2 positrons + 2 neutrinos b) 2 protons + 2 neutrons → 4He + 2 electrons + 1 neutrino c) 4 protons → 4He + 1 neutrino + 1 positron d) 2 protons + 2 electrons → 4He + 2 positrons
4 protons → 4He + 2 positrons + 2 neutrinos
Half-life of Uranium (238U)
4.5 billion years range of ages that can be determined (years) 10 million--4.54 billion Final stable Isotope is Lead (206Pb)
Half-life of Rubidium (87 Rb)
47.0 billion years Range of ages that can be determined (years) 10 million--4.54 billion Final stable Isotope is Strontium (87Sr)
Jupiters distance from the Sun
5 AU
Half-life of Carbon (14C)
5730 range of ages that can be determined (years) 100-70,000 Final stable Isotope Nitrogen (14N)
What is a Trans-Neptunian Object? 1. A Trans-Neptunian Object is a small body of rock and ice that orbits the Sun beyond the orbit of Neptune. 2. A Trans-Neptunian Object is a small body of rock and ice that orbits the Sun in an elliptical orbit, which takes it near the Sun and then out beyond the orbit of Neptune.
A Trans-Neptunian Object is a small body of rock and ice that orbits the Sun beyond the orbit of Neptune.
A) If you start with 0.80 kg of radioactive potassium (40K), how much will remain after 1.3 billion years? 1. none 2. 0.20 kg 3. 0.40 kg B) How much will remain after 2.6 billion years? 1. none 2. 0.20 kg 3. 0.10 kg C) How much will remain after 3.9 billion years? 1. 0.10 kg 2. 0.05 kg 3. none D) How long would you have to wait until there was no 40K remaining? 1. forever 2. 13 billion years 3. 1.3 billion years
A) 0.40 kg B) 0.20 kg C) 0.10 kg D) forever Half-life for Potassium is 1.3 billion range of ages that can be determined (Years) 50,000--4.54 billion Final stable Isotope is Argon (40Ar)
Why do nuclear fusion reactions, like those in the Sun, take place only at high temperatures? 1. The high temperatures are a result of the energy released in the reactions. They are not actually needed to produce the reactions. 2. To undergo fusion reactions, a nucleus must separate into its constituent particles (neutrons and protons), and this happens only at high temperatures. 3. The high temperatures are needed to ionize the atoms (to strip them of their electrons) so that the bare nuclei can interact. 4. All nuclei are positive, and high temperatures—and the high velocities that go with them—are necessary to force these repulsive nuclei together.
All nuclei are positive, and high temperatures—and the high velocities that go with them—are necessary to force these repulsive nuclei together.
Which of the following best describes the orbits of the inner planets? 1. Half of the planets orbit clockwise, half counterclockwise. 2. Individual orbits randomly reverse direction. 3. Individual orbits predictably reverse direction. 4. All of the planets orbit counterclockwise.
All of the planets orbit counterclockwise.
Which of the following best describes the orbits of the outer planets? 1. One of the planets revolves clockwise, while the rest revolve counterclockwise. 2. Individual orbits randomly reverse direction. 3. Individual orbits predictably reverse direction. 4. All of the planets orbit counterclockwise.
All of the planets orbit counterclockwise.
What is an asteroid? 1. An asteroid is a small rocky body orbiting the Sun in the inner part of the solar system. Asteroids are debris left over from a planet that was destroyed early in the history of the solar system. 2. An asteroid is a small rocky body orbiting the Sun in the inner part of the solar system. Asteroids are debris left over from the original formation of the solar system.
An asteroid is a small rocky body orbiting the Sun in the inner part of the solar system. Asteroids are debris left over from the original formation of the solar system.
The graphite in your pencil is a form of carbon. Where were these carbon atoms formed? 1. Carbon is formed by nuclear reactions in stars. At the ends of their lives, stars can erupt in novae or supernovae, and these send elements like carbon across the interstellar medium. 2. Heavy elements like carbon are formed only in supernovae.
Carbon is formed by nuclear reactions in stars. At the ends of their lives, stars can erupt in novae or supernovae, and these send elements like carbon across the interstellar medium.
The surfaces of Mercury, the Moon, and Mars are riddled with craters formed by the impact of space debris. Many of these craters are billions of years old. By contrast, there are only a few conspicuous craters on Earth's surface, and these are generally less than 500 million years old. Why this difference? 1. Earth is a geologically active planet, and the surface also experiences erosion. Plate tectonics, in particular, have resurfaced the planet and removed the older craters. The other bodies have been geologically inactive for billions of years. 2, Earth's surface is three quarters water. Most of the space debris that strikes us lands in the ocean without making a crater, so only the continents have craters.
Earth is a geologically active planet, and the surface also experiences erosion. Plate tectonics, in particular, have resurfaced the planet and removed the older craters. The other bodies have been geologically inactive for billions of years.
Nuclear fusion converts mass into energy. This means that by the time all of the hydrogen in the core of the Sun has been fused into helium, the Sun will be substantially less massive. True False
False
The Sun's light is produced by three main sources: gravitational contraction, chemical burning, and nuclear fusion. True False
False
The tides cause ocean water to circulate around the world. True False
False
The complete solar magnetic cycle repeats approximately every 11 years. True False
False The total magnetic cycle is 22 years when polarity reversals are taken into account.
The internal heat energy of the Sun largely comes from which of the following products released in the proton-proton chain? 1. Gamma rays 2. He nucleus 3. Neutrino 4. Positron 5. Deuteron
Gamma rays
Which planet is moving fastest? 1. Jupiter 2. Saturn 3. Uranus 4. Neptune 5. They are all moving with the same speed.
Jupiter
Mercury rotates once on its axis every 58.646 days, compared to one day for Earth. Based on this information, how would you expect Mercury's magnetic field to compare with Earth's magnetic field? 1. Magnetic fields in a body are produced by electric currents, which are created when the body rotates. The faster it rotates, the larger the current, and the stronger the magnetic field. So Earth's magnetic field is much larger than Mercury's. 2. When a body rotates, the magnetic fields inside it become twisted and distorted. This is especially evident in the Sun, but it is true for planets and satellites as well. So the strongest magnetic fields exist in bodies that do not rotate (or rotate slowly) so that the fields are undisturbed. Thus Mercury has a stronger magnetic field than Earth.
Magnetic fields in a body are produced by electric currents, which are created when the body rotates. The faster it rotates, the larger the current, and the stronger the magnetic field. So Earth's magnetic field is much larger than Mercury's.
Which planet has the longest year? 1. Mercury 2. Venus 3. Earth 4. Mars 5. Their years are all the same length.
Mars
Which planet is moving fastest? 1. Mercury 2. Venus 3. Earth 4. Mars 5. They are all moving with the same speed.
Mercury
Are all the planetary orbits circular? 1. Yes. All of the planetary orbits are nearly circular. 2. No. None of the planetary orbits are even close to being circular. 3. Most of the planetary orbits are nearly circular.
Most of the planetary orbits are nearly circular.
Which planet has the longest year? 1. Jupiter 2. Saturn 3. Uranus 4. Neptune 5. Their years are all the same length.
Neptune
Which of the following products of the proton-proton chain has little or no mass and no charge? 1. Gamma rays 2. He nucleus 3. Neutrino 4. Positron 5. Deuteron
Neutrino
Does Eros lie in the asteroid belt? 1. Yes. Eros' semi-major axis is larger than that of Mars. 2. Yes. All asteroids lie within the asteroid belt, by definition. 3. No. Eros' semi-major axis is inside the orbit of Mars.
No. Eros' semi-major axis is inside the orbit of Mars
What is the evidence that other stars existed before our Sun was formed? 1. The collapse of the gas and dust cloud to form the solar nebula could only have been triggered by a supernova explosion, and this requires an earlier generation of stars. 2. Our Sun is not massive enough and consequently not hot enough to produce heavy elements. Yet heavy elements exist in the Sun, and these must have been formed in an earlier generation of hot, massive stars.
Our Sun is not massive enough and consequently not hot enough to produce heavy elements. Yet heavy elements exist in the Sun, and these must have been formed in an earlier generation of hot, massive stars.
How does the size of a terrestrial planet influence the amount of cratering on the planet's surface? 1. Small planets show less evidence of cratering for two reasons. A smaller planet tends to present a smaller target to debris moving through the solar system. Also, a planet's gravity pulls in objects that might otherwise miss the planet. So, small planets with less gravitational pull tend to avoid cratering. 2. Smaller bodies retain less of their internal heat and thus have less geologic activity. Geologic activity re-surfaces a planet and obliterates craters, so small planets tend to retain more evidence of cratering.
Smaller bodies retain less of their internal heat and thus have less geologic activity. Geologic activity re-surfaces a planet and obliterates craters, so small planets tend to retain more evidence of cratering.
How does the interstellar medium become enriched over time with heavy elements? 1. On some planets the gravitational force is insufficient to trap the atmosphere and keep it close to the planet. On such planets, the escaping atmosphere contributes heavy elements to the interstellar medium. 2. Supernovae form heavy elements and spew them throughout the interstellar medium when they erupt.
Supernovae form heavy elements and spew them throughout the interstellar medium when they erupt.
Why did the terrestrial planets form close to the Sun whereas the Jovian planets formed far from the Sun? 1. The gravitational pull of the Sun drew all the heavy materials (out of which the terrestrial planets are composed) into the inner part of the solar system and left all the lighter materials (out of which the Jovian planets are composed) in the outer part of the solar system. 2. Terrestrial planets are composed mainly of rock, which remains solid at the relatively high temperatures near the Sun. The Jovian planets contain an abundance of light gases like hydrogen and helium, which would have escaped if the temperature had been higher and the average molecular speeds larger.
Terrestrial planets are composed mainly of rock, which remains solid at the relatively high temperatures near the Sun. The Jovian planets contain an abundance of light gases like hydrogen and helium, which would have escaped if the temperature had been higher and the average molecular speeds larger.
What is the difference between disk instability models Vs Core model?
The Core Accretion Model Grains of dust in the solar nebula attract each and clump together through gravity to form planetesimals. In the inner solar system, due to the heat generated by the protosun, heavier elements such as iron, nickel, etc accrete to form planetesimals and hence the solid, dense nature of the terrestrial planets (i.e. Mercury, Venus, Earth, Mars). The outer Jovian planets (i.e. Jupiter, Saturn, Uranus and Neptune) formed through a similar process of core accretion. However, due to the lower temperature in the outer solar system the cores contained much more ice making them generally less dense. These cores reached a point where they started to attract large amounts of Hydrogen and Helium in the outer solar system and thus formed what we call the gas giants. Disk Instability Model Some astronomer theorise that the Jovian planets all formed through pure contraction of gas under gravitational attraction. They postulate that due to the non-uniform nature of the material in the solar nebula, areas of gas started to clump and rotate around their common centre of gravity (due to the conservation of momentum). As the process accelerated and more gas treamed in, dense gaseous cores formed and the thus the gas giants were born. The problem with both models is that the planets such as Neptune and Uranus couldn't have formed as gas giants so far out in the solar system. So how did they get where they are? Finally, of the two models presented above, which one is the more plausible model for planetary formation?
Why do smaller worlds retain less of their internal heat? 1. The amount of heat energy a body contains is proportional to its volume, and the volume is proportional to the cube of the radius. On the other hand, the rate at which heat leaks out of a body is proportional to its surface area, and this is proportional to its radius squared. A body will retain its heat longer if it has a large volume compared to its surface area. The ratio of volume to area is proportional to radius, so objects with a larger radius retain heat longer. 2. The amount of heat energy a body contains is proportional to its volume, and the volume is proportional to the square of the radius. On the other hand, the rate at which heat leaks out of a body is proportional to its surface area, and this is proportional to its radius. A body will retain its heat longer if it has a large volume compared to its surface area. The ratio of volume to area is proportional to radius, so objects with a larger radius retain heat longer.
The amount of heat energy a body contains is proportional to its volume, and the volume is proportional to the cube of the radius. On the other hand, the rate at which heat leaks out of a body is proportional to its surface area, and this is proportional to its radius squared. A body will retain its heat longer if it has a large volume compared to its surface area. The ratio of volume to area is proportional to radius, so objects with a larger radius retain heat longer.
What is meant by the average density of a planet? 1. The average density of a planet is the total mass divided by the total volume. 2. The average density of a planet is the total mass of the planet divided by the mass of an equivalent volume of water.
The average density of a planet is the total mass divided by the total volume.
What does the average density of a planet tell us? 1. If the average density of a planet is less than one, the planet would float in water (like Saturn). If the average density is greater than one, the planet would not float in water (like Earth). 2. The average density of a planet tells us whether the interior is primarily heavy materials like iron and rock or lighter materials like gases and liquefied gases.
The average density of a planet tells us whether the interior is primarily heavy materials like iron and rock or lighter materials like gases and liquefied gases.
What is the interstellar medium? 1. The interstellar medium is the rarified material that exists throughout the solar system, in the space between the planets. 2. The interstellar medium is the rarified material that exists in the space between the stars.
The interstellar medium is the rarified material that exists in the space between the stars.
Why do most of the satellites of Jupiter orbit that planet in the same direction that Jupiter rotates? 1. The major satellites of Jupiter are thought to have condensed out of a nebula around Jupiter, much like the planets condensed out of the solar nebula. The entire Jupiter nebula was rotating in the same direction. 2. The major satellites of Jupiter are thought to have been expelled from Jupiter because of its very large rotation rate. These were ejected in the equatorial plane, where the rotation was fastest, and thus move in same direction as Jupiter rotates.
The major satellites of Jupiter are thought to have condensed out of a nebula around Jupiter, much like the planets condensed out of the solar nebula. The entire Jupiter nebula was rotating in the same direction.
Saturn's satellite Titan has an appreciable atmosphere, yet Jupiter's satellite Ganymede—which is about the same size and mass as Titan—has no atmosphere. Why is there a difference? 1. The presence or absence of an atmosphere depends on a comparison of the escape speed and the average molecular speed on the planet. Escape speed depends on the size and mass of the body, so these are about the same. Average molecular speed depends on temperature. Since Titan is much farther from the Sun than is Ganymede, its temperature is lower, its average molecular speed is lower, and fewer of its molecules have sufficient speed to escape. 2. The presence or absence of an atmosphere depends entirely on composition. Titan is like Saturn, and its interior contains materials like methane and hydrocarbons, which are easily expelled to the surface through volcanoes. Ganymede is more like Earth—its volcanoes would expel magma (molten rock) except that it is too cold at that distance from the Sun. So nothing is expelled, and it has no atmosphere.
The presence or absence of an atmosphere depends on a comparison of the escape speed and the average molecular speed on the planet. Escape speed depends on the size and mass of the body, so these are about the same. Average molecular speed depends on temperature. Since Titan is much farther from the Sun than is Ganymede, its temperature is lower, its average molecular speed is lower, and fewer of its molecules have sufficient speed to escape.
The orbits of the planets, as seen from above and from the side, suggest which of the following about the formation of the solar system? 1. The solar system formed from two counter-rotating disks of gas and dust. 2. The solar system formed from a single rotating disk of gas and dust. 3. The solar system formed when clumps of matter coming in from many directions began orbiting together. 4. The solar system formed from two disks of gas and dust that were originally rotating perpendicularly to each other.
The solar system formed from a single rotating disk of gas and dust.
Why are terrestrial planets smaller than Jovian planets? 1. There was far more material available for planet formation in the outer part of the solar nebula (where ices could exist) than in the inner part. Thus the planets that formed in the outer part were larger. 2. The Jovian planets probably formed farther out from the Sun than their present location. They are mostly gas, and when they moved closer to the Sun, the higher temperatures made them expand.
There was far more material available for planet formation in the outer part of the solar nebula (where ices could exist) than in the inner part. Thus the planets that formed in the outer part were larger.
Which of the following best describes the planes of the planets' orbits? 1. They all lie extremely close to the plane of the ecliptic (the plane of Earth's orbit). 2. They are randomly distributed. 3. They are all nearly perpendicular to the plane of the ecliptic. 4.Half lie close to the plane of the ecliptic, half lie nearly perpendicular to it.
They all lie extremely close to the plane of the ecliptic (the plane of Earth's orbit).
In what ways are asteroids and Trans-Neptunian Objects like and unlike planets? 1. They are both like planets in that they orbit the Sun in prograde orbits very close to the plane of the ecliptic, but they are unlike planets in that they are small, very numerous, and have not "cleaned out" their neighborhood of the solar system. Also, their orbits tend to be highly elliptical. 2. They are both like planets in that they orbit the Sun in prograde orbits, but they are unlike planets in that they are small, very numerous, and have not "cleaned out" their neighborhood of the solar system.
They are both like planets in that they orbit the Sun in prograde orbits, but they are unlike planets in that they are small, very numerous, and have not "cleaned out" their neighborhood of the solar system.
Which of the following are among the seven giant satellites?
Triton the Moon Ganymede Io Titan
Based on the amount of hydrogen in its core, our Sun will generate energy via the proton-proton cycle for about 10 billion years. True False
True
Cold ocean currents flow deep in the ocean. True False
True
The energy arriving from the Sun is usually greatest at or near the equator. True False
True
There is no actual burning in nuclear burning. True False
True
The energy released by a single solar flare can exceed the total amount of energy produced by the solar core per second. True False
True Large flares have been known to release as much as 1030 joules of energy.
Could you use a compass to find your way around Venus? 1. Venus has no magnetic field, so a compass would not be useful. 2. Venus has no planet-wide magnetic field, but it does have remnant fields from a historic planet-wide field. These would be useful in navigation.
Venus has no magnetic field, so a compass would not be useful.
Do all the planets orbit the Sun in the same direction? 1. Yes. All the planets orbit the Sun in the same direction. 2. No. Venus has a retrograde orbit. 3. No. The planets have a random mix of prograde and retrograde orbits.
Yes. All the planets orbit the Sun in the same direction.
(a) Assuming that the current rate of hydrogen fusion in the Sun remains constant, what fraction of the Sun's mass will be converted into helium over the next 5 billion years? 1. 25% 2. 30% 3. 5.0% (b) How will this affect the overall chemical composition of the Sun? 1. The composition will change only slightly, from about 74% hydrogen and 25% helium to about 69% hydrogen and 30% helium. 2. The most significant change will be in the amount of heavy elements, which will increase from about one percent to almost 10 percent. 3. The composition will change significantly, from less than 50% helium now to more than 50% helium in five billion years.
a) 5.0% b) The composition will change only slightly, from about 74% hydrogen and 25% helium to about 69% hydrogen and 30% helium.
What are the characteristics of a Jovian planet?
contain much hydrogen and helium large diameters (five or more times Earth) low average densities
Which of the following is NOT caused by magnetic field activity on the Sun? 1. sunspots 2. prominences 3. convective cells 4. flares 5. coronal mass ejections
convective cells Convective cells are found in the convective layer of the Sun; they are created when low-lying material is heated by absorption of radiation traveling up from the radiative zone, causing the material to become buoyant and rise.
Which three of the following properties of the solar system are thought to be a result of how the solar system formed? (Select all that apply.) 1. directions and orientations of planetary orbits compared to the Sun's rotation 2. only eight planets 3. size and composition of the terrestrial planets versus the Jovian planets 4. clockwise rather than counter-clockwise rotation of planets 5. size of terrestrial planetary orbits versus Jovian planetary orbits
directions and orientations of planetary orbits compared to the Sun's rotation size and composition of the terrestrial planets versus the Jovian planets size of terrestrial planetary orbits versus Jovian planetary orbits
Which force prevents protons from fusing in the Sun at temperatures below 10 million Kelvins? 1. electromagnetic force 2. gravitational force 3. strong nuclear force 4. weak nuclear force
electromagnetic force
Which of the following characterize terrestrial planets?
have a definite surface relatively small (size of Earth) high average densities composed primarily of rocky materials
At least some of the largest satellites have characteristics that are dissimilar to characteristics of the terrestrial planets. Which of the following are among them
low average densities composition includes much ice
Some energy is generated in the proton-proton cycle as the result of the annihilation of which two particles? 1. electron & proton 2. positron & electron 3. proton & neutron 4. positron & neutrino
positron & electron
The largest satellites have some characteristics that are similar to characteristics of the terrestrial planets. Which of the following are among them?
similar sizes (diameters 3000—13,000 km) have a definite surface
If sunspot pairs in the northern hemisphere have north/south polarity, then pairs in the southern hemisphere will have which of the following? 1. north/south polarity 2. south/north polarity 3. north/north polarity 4. south/south polarity
south/north polarity The polarity of sunspot pairs is always opposite between the two hemispheres, so if the northern pairs have north/south polarity, then the southern pairs will have south/north polarity.
What force keeps the protons in a nucleus bound together? 1. electromagnetic force 2. gravitational force 3. strong nuclear force 4. weak nuclear force
strong nuclear force
What are at the bases of prominences? 1. flares 2. spicules 3. field loops 4. sunspots
sunspots Sunspots are areas on the surface of the Sun where magnetic field loops emerge from, or rejoin, the solar surface.
Hydrostatic equilibrium tells us that 1. the force of gas pressure outward is balanced by the pull of gravity inward. 2. convectively moving gas is always replaced by an equal amount of fresh gas. 3. the energy produced in the core of the Sun is balanced by the flow of energy from the Sun's surface into space. 4. the centripetal force outward due to the Sun's rotation is balanced by the force of gravity inward.
the force of gas pressure outward is balanced by the pull of gravity inward.
