The Northern Lights
The 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！
練習(xí)：
1.The Sun's gravity is too weak to keep its plasma from flowing to the Earth.
A Right B Wrong C Not mentioned
2.The Earth is quite safe with a magnetic field surrounding it to protect it from the attack by the solar wind.
A Right B Wrong C Not mentioned
3.Some scientists are worrying about the possible disappearance of the Earth's protective magnetic field in the future.
A Right B Wrong C Not mentioned
4.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 Right B Wrong C Not mentioned
5.You cannot see the Northern Lights unless you are in Alaska or Canada.
A Right B Wrong C Not mentioned
6.Tens of thousands of tourists take special trips to Norway and Sweden every year to watch the Northern Lights.
A Right B Wrong C Not mentioned
7.An aurora is generally close to the ground and is very long and thick.
A Right B Wrong C Not mentioned
答案與題解：
1.B 題句意思是：太陽的重力太弱，等離子逃離太陽，流向地球。這一說法與短文第一段第一、二句表達(dá)的內(nèi)容不符。句子表達(dá)的重點(diǎn)不是太陽的重力太弱，而是太陽太熱，其活動又太劇烈，造成等離子逃離太陽，流向地球。所以，答案是選項(xiàng)B.
2.A 題句說地球相當(dāng)安全，因?yàn)橛写艌鲈诟呖瞻鼑厍?，將太陽風(fēng)擋在地球大氣層外面。題句表達(dá)的意思與短文第二段第一句傳遞的信息相符。雖然短文中沒有用safe這個詞，但是“don‘t worry because a protective magnetic field surrounds our planet”包含了safe這層意思，所以選項(xiàng)A是答案。
3.C 題句說，有些科學(xué)家擔(dān)心包圍地球起防護(hù)作用的磁場有一天會消失。短文中找不到這一信息，所以答案是C.
4.A 短文第二、三段解釋極光的成因。當(dāng)強(qiáng)大的太陽風(fēng)侵入地球磁場，磁場的磁力線會斷開和閉合，等離子流的電子進(jìn)入大氣層，流向極地上空，與大氣層的氣體分子發(fā)生碰撞，發(fā)出極光。題句表達(dá)的意思與短文介紹的極光成因相符，所以答案是A.
5.B 題句的說法明顯與短文第三段的敘述不符。第四段介紹說，當(dāng)太陽風(fēng)暴達(dá)到峰期間，明亮的北極光甚至在位于極南面的佛羅里達(dá)州乃至墨西哥都能看到。所以答案是B.
6.C 題句說，每年有幾萬游客專程前往挪威和瑞典觀看北極光。短文中找不到這一內(nèi)容，所以答案是C.
7.B 題句說極光通常很接近地面，又長又厚。這一說法有兩點(diǎn)與短文第五段的介紹不符。第一點(diǎn)，極光不是接近地面，而是“似乎很接近地面（Auroras often seem to be very close to the ground）”，事實(shí)上，最靠近地面的極光離地面也有100公里。第二點(diǎn)，極光不厚，“only a few hundred meters thick”。所以答案是B.
The 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！
練習(xí)：
1.The Sun's gravity is too weak to keep its plasma from flowing to the Earth.
A Right B Wrong C Not mentioned
2.The Earth is quite safe with a magnetic field surrounding it to protect it from the attack by the solar wind.
A Right B Wrong C Not mentioned
3.Some scientists are worrying about the possible disappearance of the Earth's protective magnetic field in the future.
A Right B Wrong C Not mentioned
4.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 Right B Wrong C Not mentioned
5.You cannot see the Northern Lights unless you are in Alaska or Canada.
A Right B Wrong C Not mentioned
6.Tens of thousands of tourists take special trips to Norway and Sweden every year to watch the Northern Lights.
A Right B Wrong C Not mentioned
7.An aurora is generally close to the ground and is very long and thick.
A Right B Wrong C Not mentioned
答案與題解：
1.B 題句意思是：太陽的重力太弱，等離子逃離太陽，流向地球。這一說法與短文第一段第一、二句表達(dá)的內(nèi)容不符。句子表達(dá)的重點(diǎn)不是太陽的重力太弱，而是太陽太熱，其活動又太劇烈，造成等離子逃離太陽，流向地球。所以，答案是選項(xiàng)B.
2.A 題句說地球相當(dāng)安全，因?yàn)橛写艌鲈诟呖瞻鼑厍?，將太陽風(fēng)擋在地球大氣層外面。題句表達(dá)的意思與短文第二段第一句傳遞的信息相符。雖然短文中沒有用safe這個詞，但是“don‘t worry because a protective magnetic field surrounds our planet”包含了safe這層意思，所以選項(xiàng)A是答案。
3.C 題句說，有些科學(xué)家擔(dān)心包圍地球起防護(hù)作用的磁場有一天會消失。短文中找不到這一信息，所以答案是C.
4.A 短文第二、三段解釋極光的成因。當(dāng)強(qiáng)大的太陽風(fēng)侵入地球磁場，磁場的磁力線會斷開和閉合，等離子流的電子進(jìn)入大氣層，流向極地上空，與大氣層的氣體分子發(fā)生碰撞，發(fā)出極光。題句表達(dá)的意思與短文介紹的極光成因相符，所以答案是A.
5.B 題句的說法明顯與短文第三段的敘述不符。第四段介紹說，當(dāng)太陽風(fēng)暴達(dá)到峰期間，明亮的北極光甚至在位于極南面的佛羅里達(dá)州乃至墨西哥都能看到。所以答案是B.
6.C 題句說，每年有幾萬游客專程前往挪威和瑞典觀看北極光。短文中找不到這一內(nèi)容，所以答案是C.
7.B 題句說極光通常很接近地面，又長又厚。這一說法有兩點(diǎn)與短文第五段的介紹不符。第一點(diǎn)，極光不是接近地面，而是“似乎很接近地面（Auroras often seem to be very close to the ground）”，事實(shí)上，最靠近地面的極光離地面也有100公里。第二點(diǎn)，極光不厚，“only a few hundred meters thick”。所以答案是B.