单选题The transition of the Earth’s magnetic field is possibly caused by _____.Athe flows of melted iron inside the EarthBthe periodical movement of the EarthCthe mechanical energy of the solar systemDthe force coming from outer space
单选题
The transition of the Earth’s magnetic field is possibly caused by _____.
A
the flows of melted iron inside the Earth
B
the periodical movement of the Earth
C
the mechanical energy of the solar system
D
the force coming from outer space
参考解析
解析：
文章最后一段：谁也不能准确地知道为什么地球磁场会周期性转换，但是科学家说其原因可能在于地壳中融化了的铁的无序流动，它们看起来就像木星上组成云的气体一样。
文章最后一段：谁也不能准确地知道为什么地球磁场会周期性转换，但是科学家说其原因可能在于地壳中融化了的铁的无序流动，它们看起来就像木星上组成云的气体一样。
相关考题：
Permanent magnetism is caused by ______.A.operation of electrical equipment and generators on board shipB.the earth's magnetic field affecting the ship's hard iron during constructionC.the horizontal component of the earth's magnetic field acting on the horizontal soft ironD.the vertical component of the earth's magnetic field acting on the vertical soft iron
The direction of prevailing winds in the Northern hemisphere is caused by the ______．A.Magnetic field at the North PoleB.Gulf StreamC.Earth's rotationD.Arctic cold fronts
共用题干The Northern LightsThe Sun is stormy and has its own kind of weather It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma,and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate,flicker,or even move like waves.During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!Some scientists are worrying about the possible disappearance of the Earth's protective magnetic field in the future.A: RightB: WrongC: Not mentioned
共用题干Solar StormAt the end of October 2003,a sudden solar storm hit the earth.A solar storm refers to the large amounts of charged particles released into space_________(1)the solar energyincreases.The release of the energy_________(2)place along with the activity of the sunspots with a cycle of 11 years.This time,the_________(3)of the storm exceeded expectations.This_________(4)of intense solar storm was caused by the eruption of a solar flare （闪光）and the ejection（喷发）of the solar corona（日冠）on October28, 2003. Large amounts of charged particles moved 150, 000,000 kilometers through space toward the _________(5)in 19 hours. They could affect aircraft roaming（漫游）in space.The high-energy particles will_________(6)some of the parts of an aircraft.They may also cause it to fail.High-energy particles can threaten the safety of an aircraft at a high orbit.If an aircraft orbits at a lower orbit,it is_________(7)because it is under the protection of the earth's magnetic field.A solar storm not only affects aircraft but also is a_________(8)to the environment and humans.The aerosphere and magnetic field of the earth can_________(9)humans from ultraviolet radiation and X-rays. While most of the X-rays are absorbed after they enter the aerosphere（大气层）,still a few can_________(10) the ground.The geomagnetic storm caused by this round of solar storm reaches its highest level on the two_________(11)of the earth,which affects electricity supply of North America. Overexposure to_________(12)threatens the health of passengers on planes flying over the Polar Regions.If we fly in the sky during such a solar storm,it_________(13)we receive ten times the X-ray radiation.It's really damaging.Scientists say a solar eruption is like the sun sneezing,which will make the earth _________(14)a cold.Though this natural force is irresistible,scientists can still _________(15)its movement accurately by monitoring.Facing successive solar storms, humans can't drop their guard._________(13)A:recommends B:means C:proposes D:advises
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!What is the author's tone toward the Northern Lights?A:Indifferent.B:Sarcastic.C:Sharp.D:Appreciative.
共用题干The Northern LightsThe Sun is stormy and has its own kind of weather It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma,and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate,flicker,or even move like waves.During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!The auroras are formed when the electrons falling into the Earth's atmosphere at the poles and colliding with gas molecules in the atmosphere.A: RightB: WrongC: Not mentioned
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!The solar wind comes into being as a result of_______.A:disappearance of the Sun's gravityB:unpredictable weather of the SunC:fast flow of energy away from the SunD:a stream of particles being blown away
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!What happens when solar wind comes to the Earth?A:It is trapped in magnetic belts around the Earth.B:A protective magnetic field is formed at the same time.C:It destroys the protective magnetic field surrounding the Earth.D:It breaks magnetic field lines and does severe damage to the Earth.
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!Which of the following statements is true of the Northern Lights?A:Their movement is slow enough to be observed with the eyes.B:People cannot see them unless traveling to Alaska or Canada.C:They are very close to the ground.D:They are very long and thick.
共用题干The Northern LightsThe Sun is stormy（狂暴的）and has its own kind of weather. It is so hot and active that even the Sun ' s gravity cannot hold its atmosphere in check（控制，支配）!Energy flows away from the Sun toward the Earth in a stream of electrified particles（电粒子）that move at speeds around a million miles per hour. These path- dles are called plasma（等离子体）, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field （磁场）surrounds our planet. The same magnetic field that makes your compass point north also steer（引导）the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles（原子粒子）called electrons（电子）trapped in the belts to fall into the Earth ' s atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules（分子）in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glow red and green and nitrogen glows violet- purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker,or even move like waves. During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far-north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!You cannot see the Northern Lights unless you are in Alaska or Canada.A:RightB:WrongC:Not mentioned
共用题干California Gives Green Light to Space Solar PowerEnergy beamed down from space is one step closer to reality,now that California has given the green light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts（兆瓦）of power beamed down from solar-power satellites beginning in 2016.But some major challenges will have to beovercome if the technology is to be used widely.A start-up company called Solaren is designing the satellites,which it says will use radio waves to beamenergy down to a receiving station on Earth.The attraction of collecting solar power in space is the almost uninterrupted sunshine available in geo- synchronous（与地球同步的）orbit. Earth-based solar cells , by contrast , can only collect sun light during day-time and when skies are clear.But space-based solar power must grapple（努力克服）with the high cost per kilogram of launching things in- to space,says Richard Schwartz of Purdue University in West Lafayette,Indiana."if you're talking about it being economically viable for power of the Earth,it's a tough go,"he says.Cal Boerman,Solaren's director of energy services,says the company designed its satellites with a view to keeping launch costs down."We knew we had to come up with a different,revolutionary design,"he says. A patent the company has won describes ways to reduce the system's weight,including using inflatable mir- rors to focus sunlight on solar cells,so a smaller number can collect the same amount of energy.But using mirrors introduces other challenges,including keeping the solar cells from overheating,says Schwartz."You have to take care of heat dissipation（散发）because you're now concentrating a lot of energy in one place,"he says.According to the company's patent,Solaren's solar cells will be connected to radia-tors to help keep them cool.Though Boerman says the company believes it can make space-based solar power work,it is not expec-ting to crowd out other forms of renewable energy.Laws in California and other states require increasing use of renewable energy in coming years,he points out."To meet those needs,we're going to need all types of renewable energy sources,"he says.Space-based solar power will rule out other forms of renewable energy sources.A:RightB:WrongC:Not mentioned
共用题干Solar StormAt the end of October 2003,a sudden solar storm hit the earth.A solar storm refers to the large amounts of charged particles released into space_________(1)the solar energyincreases.The release of the energy_________(2)place along with the activity of the sunspots with a cycle of 11 years.This time,the_________(3)of the storm exceeded expectations.This_________(4)of intense solar storm was caused by the eruption of a solar flare （闪光）and the ejection（喷发）of the solar corona（日冠）on October28, 2003. Large amounts of charged particles moved 150, 000,000 kilometers through space toward the _________(5)in 19 hours. They could affect aircraft roaming（漫游）in space.The high-energy particles will_________(6)some of the parts of an aircraft.They may also cause it to fail.High-energy particles can threaten the safety of an aircraft at a high orbit.If an aircraft orbits at a lower orbit,it is_________(7)because it is under the protection of the earth's magnetic field.A solar storm not only affects aircraft but also is a_________(8)to the environment and humans.The aerosphere and magnetic field of the earth can_________(9)humans from ultraviolet radiation and X-rays. While most of the X-rays are absorbed after they enter the aerosphere（大气层）,still a few can_________(10) the ground.The geomagnetic storm caused by this round of solar storm reaches its highest level on the two_________(11)of the earth,which affects electricity supply of North America. Overexposure to_________(12)threatens the health of passengers on planes flying over the Polar Regions.If we fly in the sky during such a solar storm,it_________(13)we receive ten times the X-ray radiation.It's really damaging.Scientists say a solar eruption is like the sun sneezing,which will make the earth _________(14)a cold.Though this natural force is irresistible,scientists can still _________(15)its movement accurately by monitoring.Facing successive solar storms, humans can't drop their guard._________(5)A:star B:earth C:moon D:sun
共用题干The Northern LightsThe Sun is stormy and has its own kind of weather It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma,and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate,flicker,or even move like waves.During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!The Earth is quite safe with a magnetic field surrounding it to protect it from the attack by the solar wind.A: RightB: WrongC: Not mentioned
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!The Northern Lights are created when_______.A:the magnetic field lines fail to reconnectB:the electrons falling to the Earth shine in different colorsC:atomic particles fall to the Earth and collide with atmospheric gas moleculesD:oxygen and nitrogen are separated from the atmospheric gases
共用题干The Northern LightsThe Sun is stormy and has its own kind of weather It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma,and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate,flicker,or even move like waves.During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!The Sun's gravity is too weak to keep its plasma from flowing to the Earth.A: RightB: WrongC: Not mentioned
共用题干The Northern LightsThe Sun is stormy and has its own kind of weather It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma,and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth's atmosphere at the poles. As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting,but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate,flicker,or even move like waves.During solar maximum,auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!An aurora is generally close to the ground and is very long and thick.A: RightB: WrongC: Not mentioned
共用题干California Gives Green Light to Space Solar PowerEnergy beamed down from space is one step closer to reality,now that California has given the green light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts（兆瓦）of power beamed down from solar-power satellites beginning in 2016.But some major challenges will have to beovercome if the technology is to be used widely.A start-up company called Solaren is designing the satellites,which it says will use radio waves to beamenergy down to a receiving station on Earth.The attraction of collecting solar power in space is the almost uninterrupted sunshine available in geo- synchronous（与地球同步的）orbit. Earth-based solar cells , by contrast , can only collect sun light during day-time and when skies are clear.But space-based solar power must grapple（努力克服）with the high cost per kilogram of launching things in- to space,says Richard Schwartz of Purdue University in West Lafayette,Indiana."if you're talking about it being economically viable for power of the Earth,it's a tough go,"he says.Cal Boerman,Solaren's director of energy services,says the company designed its satellites with a view to keeping launch costs down."We knew we had to come up with a different,revolutionary design,"he says. A patent the company has won describes ways to reduce the system's weight,including using inflatable mir- rors to focus sunlight on solar cells,so a smaller number can collect the same amount of energy.But using mirrors introduces other challenges,including keeping the solar cells from overheating,says Schwartz."You have to take care of heat dissipation（散发）because you're now concentrating a lot of energy in one place,"he says.According to the company's patent,Solaren's solar cells will be connected to radia-tors to help keep them cool.Though Boerman says the company believes it can make space-based solar power work,it is not expec-ting to crowd out other forms of renewable energy.Laws in California and other states require increasing use of renewable energy in coming years,he points out."To meet those needs,we're going to need all types of renewable energy sources,"he says.Solar-power satellites will use radio waves to beam energy down from space.A:RightB:WrongC:Not mentioned
单选题Deviation is caused by（）.Achanges in the earth's magnetic fieldBnearby magnetic land masses or mineral depositsCmagnetic influence inherent to that particular vesselDthe magnetic lines of force not coinciding with the lines of longitude
单选题During the transition of the Earth’s magnetic field _____.Athe compass will become uselessBman and animals will be confused as to directionsCthe magnetic strength of the Earth will disappearDthe magnetic strength of the Earth will be stronger
单选题Variation in a compass is caused by（）.Aworn gears in the compass housingBmagnetism from the earth's magnetic fieldCmagnetism within the vesselDlack of oil in the compass bearings
单选题According to the passage, _____.Awe should not worry about the transition of the Earth’s magnetic fieldBthe Earth’s magnetic field will not change for at least 2000 yearsCthe Earth’s magnetic field has decreased its strength rapidlyDthe transition of the Earth’s magnetic field can be controlled by modern science
单选题Permanent magnetism is caused by（）.Aoperation of electrical equipment and generators on board shipBthe earth's magnetic field affecting the ship's hard iron during constructionCthe horizontal component of the earth's magnetic field acting on the horizontal soft ironDthe vertical component of the earth's magnetic field acting on the vertical soft iron
单选题We learn from the passage that ______.Aall living things on the earth depend on the sun for their foodBa forest looks dark in winter because it absorbs solar energyConly 0.023 of the energy from the sun is made use of on the earthDgreenhouse gases allow heat energy to escape from the earth’ s surface
单选题The vertical component of the Earth’s magnetic field causes induced magnetism in vertical soft iron. This changes with latitude. What corrects for this coefficient of the deviation? （）AThe Flinders barBThe heeling magnetCQuadrantal soft iron spheresDBar magnets in the binnacle
单选题Compass deviation is caused by（）.Amagnetism from the earth's magnetic fieldBmisalignment of the compassCmagnetism within the vesselDa dirty compass housing
单选题At the magnetic equator there is no induced magnetism in the vertical soft iron because（）.Athe lines of force cross the equator on a 0°-180°alignmentBthe quadrantal error is 0°Cthere is no vertical component of the Earth's magnetic fieldDthe intercardinal headings have less than 1°
单选题The magnetic compass magnets are acted on by the horizontal component of the Earth’s total magnetic force. This magnetic force is GREATEST at the（）.Anorth magnetic poleBsouth magnetic poleCmagnetic prime vertical meridianDmagnetic equator