The earth has many mysteries for people to explore and we live on the earth for protection. Do you know that the earth has two North Poles? There’s the geographic North Pole, which never changes. And there’s the magnetic (有磁性的) North Pole, which is always on the move. Over the past 150 years, the magnetic North Pole has casually wandered 685 miles across northern Canada. But right now it’s racing 25 miles a year to the northwest. This could be a sign that we’re about to experience something humans have never seen before: a magnetic polar flip (翻转). And when this happens, it could affect much more than just your compass.
Right now on the surface of the planet, it looks like it’s just a bar magnet. Our compasses are just pointing to one pole at a time because there’s mainly a two-pole system. But sometimes, the earth doesn’t just have a single magnetic North and South Pole. Evidence suggests that, for hundreds to thousands of years at a time, our planet has had four, six, and even eight poles. This is what has happened when the magnetic poles flipped in the past. And when it happens again, it won’t be good news for humans.
Now you might think, eight poles must be better than two. But the reality is that multiple magnetic fields would fight each other. This could weaken the earth’s protective magnetic field by up to 90% during a polar flip.
The earth’s magnetic field is what protects us from harmful space radiation which can damage cells and cause cancer. With a weaker field in place, some scientists think this could expose planes to higher levels of radiation, making flights less safe.
This could also interrupt the internal sense of direction in many animals that use the magnetic field for navigation (导航). Even worse, it could make certain places on the planet too dangerous to live in. But what exactly will take place on the surface is less clear than what will undoubtedly happen in space.
Satellites and space missions will need extra shelter that we’ll have to provide ourselves. Without it, intense universal and solar radiation will fry circuit boards and increase the risk of cancer in astronauts.
12. Which of the following can best describe the earth’s magnetic field?
A.The focus of scientific research. | B.The navigation of satellites. |
C.The center of the universe. | D.The protective umbrella of humans. |
13. What will some animals be faced with when the magnetic poles flip?
A.Losing the ability to hunt for food. |
B.Bearing very loud noise day and night. |
C.Being unable to find directions exactly. |
D.Being unable to protect themselves from danger. |
14. What can we learn from the text?
A.Astronauts are more likely to suffer from cancer. |
B.The magnetic North Pole is moving faster than before. |
C.Flights aren’t allowed to travel as usual when the magnetic poles flip. |
D.There are always more than two magnetic poles on the earth at a time. |
15. What may be the best title for the text?
A.What will happen when the poles flip? | B.The ways that scientists research poles |
C.How and when will the poles flip? | D.The reasons why scientists research poles |