Blockson's computer model reveals that at the South Atlantic Anomaly, the magnetic field isn't just weaker than anywhere else on the planet. It's actually reversed polarity. There is a patch on the core in the South Atlantic where things are not poin

发表于:2019-01-22 / 阅读(68) / 评论(0) 分类 自然百科2011年

Larry Newitt from the Geological Survey of Canada charts the movement of the magnetic North Pole as it wanders the icy reaches of northern Canada. To determine where the magnetic pole / is, we can't rely on one single observation. What I try to do is

发表于:2019-01-22 / 阅读(71) / 评论(0) 分类 自然百科2011年

As the vast sphere reaches / maximum speed, something incredible happens. Huge lines of magnetism arc in and out of the model core. Well, we can't see the magnetic field coming out of the experiment, we can measure them, we can put many different mag

发表于:2019-01-22 / 阅读(71) / 评论(0) 分类 自然百科2011年

Easily confused by this idea, there has a big thawed iron inner core, so that I think it's just the bar magnet, just permanent magnet frozen in nad, and that's where causes all the magnetic field. But it's too hot inside the Earth, that can't happen

发表于:2019-01-22 / 阅读(68) / 评论(0) 分类 自然百科2011年

The loss of the magnetic field has a catastrophic impact on the planet's evolution. Mars becomes the red planet we see today. If earths magnetic protection continues to fade, would it suffer the same fate? If it vanishes completely, the planet might

发表于:2019-01-22 / 阅读(78) / 评论(0) 分类 自然百科2011年

It's clear from the fact that the Martian crust is strongly magnetized, that there must have been a magnetic field on Mars in the past, that the only way we know to magnetize rocks is for them to form in the presence of magnetic field. Why did Mars l

发表于:2019-01-22 / 阅读(58) / 评论(0) 分类 自然百科2011年

Scientists believe that the South Atlantic Anomaly, is a sign of a global decline in the magnetic field. Evidence of this comes from a surprising source. Dr. Mimi Hill uses pottery to uncover the secrets of earth's magnetic past. Ancient pots tell us

发表于:2019-01-22 / 阅读(66) / 评论(0) 分类 自然百科2011年

In polar regions where the magnetic field is / weakest, auroras glow in the sky. These dazzling displays of colored lights form when solar particles slam into gases in our atmosphere causing them to glow. The stronger the solar wind, the more dramati

发表于:2019-01-22 / 阅读(74) / 评论(0) 分类 自然百科2011年

If we could flip a switch and just turn off the Earth's magnetic field, it will take about 15,000 years to disappear, based on the rate of decay of the field that we've seen over the last 150 years. It's currently decaying at a rate that would see an

发表于:2019-01-22 / 阅读(62) / 评论(0) 分类 自然百科2011年

By analyzing different samples of lava, Herrero / Bervera has built up a picture of how the filed has changed since long before humans were around. They are actually the recorders of the Earth's magnetic field in hundreds of years, thousands of years

发表于:2019-01-22 / 阅读(73) / 评论(0) 分类 自然百科2011年

We drive them about 20 miles away to the North, and release them, and we track them as they try to fly back home. We drive them about 20 miles away to the North, and release them, and we track them as they try to fly back home. Hes up, OK. Holland wa

发表于:2019-01-22 / 阅读(72) / 评论(0) 分类 自然百科2011年

By analyzing thousands of lava samples, geophysicists discover/ that the Earth's magnetic field has reversed over 18,000 times in the last 20 million years. On either side of these reversals is a long period of dramatically reduced field strength. Du

发表于:2019-01-22 / 阅读(62) / 评论(0) 分类 自然百科2011年

Glatsmire's model shows that the magnetic poles swap places spontaneously due to / complex processes within the core. We were used to the idea that a compass points somewhere near the North Pole and hence we can use it for navigation, but there are p

发表于:2019-01-22 / 阅读(63) / 评论(0) 分类 自然百科2011年

Six years later, they come to believe these light flashes are the results of high energy, heavy cosmic rays penetrating the spacecraft and the crew members' eyes. These/ protons or electrons, just very, very high energy, ripped / part of atoms, sprin

发表于:2019-01-22 / 阅读(79) / 评论(0) 分类 自然百科2011年

During its magnetic cycle, the Sun undergoes periodic changes in activity. Every 11 years, it enters solar maximum. This 11 years cycle of solar activity has peaks where theres lots of solar storms. And right now where the sun is taking a little napp

发表于:2019-01-22 / 阅读(102) / 评论(0) 分类 自然百科2011年

In about four or five billion years, it will grow into a much bigger star, a star called a red giant. And that outer atmosphere of gases will be held so loosely by the sun at that time that the gases will be blown away gently in what I call a cosmic

发表于:2019-01-22 / 阅读(66) / 评论(0) 分类 自然百科2011年

We are at a foundry here, and they are pouring molten iron from all machinery. And they are going to make parts for new machines out of that iron, so they are recycling yet, but all that iron was created and ejected into the cosmos by gigantic stars

发表于:2019-01-22 / 阅读(70) / 评论(0) 分类 自然百科2011年

Once theyve caught the light of a dying star with their state of our telescopes. The detective work can begin. We collect that light and we analyze it in great detail in order to determine whats going on, whats the chemical makeup of the star, whats

发表于:2019-01-22 / 阅读(61) / 评论(0) 分类 自然百科2011年

To understand how these calamities occur, astronomers need to catch a massive star in its death throes. Astronomers are like detectives. We have to figure out what's going on in the universe, sometimes based on a minimum number of clues. And in the c

发表于:2019-01-22 / 阅读(73) / 评论(0) 分类 自然百科2011年

Like nebulae which spawn stars, it is made of gas and dust. But that's where most similarities end. For Alex Filippenko, it represents an intriguing industrial zone within our galaxy where the elements from which our world is made or manufactured. Wh

发表于:2019-01-22 / 阅读(77) / 评论(0) 分类 自然百科2011年