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 part
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The Northern Lights
The 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!
The Northern Lights
The 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:Right
B:Wrong
C:Not mentioned
A:Right
B:Wrong
C:Not mentioned