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核变化引发地球磁场变化 卫星恐失去保护
核变化引发地球磁场变化 卫星恐失去保护
5 ~, B) T3 Y, o: A2008-08-20 11:50:23 来源: 网易探索(广州)
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美国科学家日前发现，地球内部的地核正在发生着变化，受此影响地球的磁场也在变化。科学家们担心地指出，这些变化将给卫星等航天器带来巨大危险。
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( g$ t3 j" p5 @- F* Y+ t地球会发生磁性逆转
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! ]/ g0 \( Y9 N地球外核指的是从地表向下2500英里至3500英里的区域，这里金属呈液体状态；地球内核指的是以地心为中心，半径500英里的区域，那里金属呈固体状态
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太阳风带来的高能粒子将使地球磁场变形
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2 E( K, u: T! u网易探索8月20日报道 据生活科学网站报道，美国科学家日前发现，地球内部的地核正在发生着变化，受此影响地球的磁场也在变化。科学家们担心地指出，这些变化将给卫星等航天器带来巨大危险，因为地球磁场对于来自外太空的高能量辐射有保护作用，就好像给卫星等航天器穿上了一层防辐射服。如果地球磁场发生了变化，那么围绕地球旋转的成千上万颗卫星和其他航天器将失去地球磁场的保护，它们将毫无保护地受到外太空高能辐射。
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2 p3 |, V/ k4 g2 N" t一项最新的研究表明，地球总磁场的弱化将会持续数百甚至上千年，直到最后磁场完全消失殆尽，但地球磁场在几个月的微小而频繁的变化都会使卫星失去保护，而这是科学家无法解决的问题。用过去9年卫星数据设立的模型可以获悉，地核内的流体运动改变地球的外围磁场的过程。这是科学家们首次发现地球磁场仅在数月内就有可能发生如此巨大的变化。
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德国科研中心所属的赫尔曼-冯-黑尔姆霍尔茨联合会（GFZ German Research Center ）一直致力于地球磁场的研究，该研究机构的地球物理学家曼德拉表示：“南大西洋的地球磁场已经出现了这些变化，该地区的磁场与地球其他地区相比较弱，仅为一般磁场的三分之一”，甚至在我们发现新的磁场变化以前，南大西洋的磁场已经出现了相当反常的现象，目前那里已经是地球磁场最薄弱的地区，这意味着地球的磁场保护网在该地区已经出现了凹陷。丹麦哥本哈根大学（University of Copenhagen ）的地球物理学家奥尔森（Nils Olsen）与曼德拉合作，二人共同确立了一个地核流体的模型，该模型计算出的结果与卫星检测到的地球磁场变化结果一致。
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由于地球磁场的弱化已经使南大西洋区域磁场出现反常，并将严重影响卫星等航天器的运行。失去了地球磁场的保护，来自太阳的辐射风暴将会干扰卫星上的电子设备。曼德拉解释称：“对于卫星来说，这是个极为严峻的挑战。太阳的辐射风暴和一些高能粒子将会使卫星的信号受到影响，并与地面失去联系。”太阳风和其他来自太阳的辐射正在频繁地对地球进行轰炸，磁场在遭到这些袭击后为地球形成了气泡保护膜，但是这种强有力的保护也并非密不透风。2006年发生的一次巨大的太阳辐射风暴使一些卫星出现了短暂的失灵。国际空间站的宇航员们也不得不进入保护区，避免暴露在核辐射之下。在过去的150年里，地球的磁场已经减弱了近10%。目前曼德拉和奥尔森正根据新的观测数据继续对模型进行修正，希望能对其进行完善，以便能精确的预测将来地球磁场的变化。
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' D7 y1 Y9 B$ ?$ `& L- b% [地球的磁场到底有多大呢？它向太空绵延58000公里，保护着我们的星球。地核能够导电，它好像一个巨大的电磁铁，地球磁场就是它在旋转过程中产生的。这些磁场形成了一个泪珠形状的气泡保护在地球表面，从而对地球上的生物形成保护膜，避免它们受到来自太阳高能的辐射。在地球漫长的历史中曾出现多次磁性逆转（magnetic reversal）的现象，最近一次发生在78万年以前。当地球南北磁性逆转后，新的磁极需要经过一段时间后才能重新确立和恢复。科学家证实，下一次磁性逆转即将发生。! u. e2 e/ [, h! R( O+ I) B( C% M
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Sloshing Inside Earth Changes Protective Magnetic FieldBy Jeremy Hsu, Staff Writer
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posted: 18 August 2008 06:35 am ET0 y0 s( u& u+ z/ X3 E/ }5 \
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4 f9 p, W/ i9 t# a. A' ]. ^! T, xThe innermost part of the earth. The outer core extends from 2500 to 3500 miles below the earth's surface and is liquid metal. The inner core is the central 500 miles and is solid metal. Credit: John Lahr, USGS Open-File Report 99-132; g. W1 N/ O- w, o
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" ~' k' g8 `/ F4 w k t6 K+ rThe solar wind is a continuous flow of particles from the Sun consisting of electrically charged particles in a state known as plasma. The Earth’s magnetic field is distorted by the solar wind to a droplet-shaped magnetic bubble called the magnetosphere. On the nightside, the Earth’s magnetic field is stretched into a long tail, the magnetotail, much like the tail of a comet. The blue cavity represents the magnetosphere. The red area denotes the region where a large amount of charged particles reside and intense electric currents flow within the magnetosphere. The four Cluster satellites encountered a flow reversal region in the magnetotail. Credit: Tony Lui, JHU/APL ; T4 k' {4 L& J( v* T% Z8 p
8 ^4 q8 |1 V& W$ oThe innermost part of the earth. The outer core extends from 2500 to 3500 miles below the earth's surface and is liquid metal. The inner core is the central 500 miles and is solid metal. Credit: John Lahr, USGS Open-File Report 99-132
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+ S* D% u6 s& k1 @7 S* P9 |) BThe solar wind is a continuous flow of particles from the Sun consisting of electrically charged particles in a state known as plasma. The Earth’s magnetic field is distorted by the solar wind to a droplet-shaped magnetic bubble called the magnetosphere. On the nightside, the Earth’s magnetic field is stretched into a long tail, the magnetotail, much like the tail of a comet. The blue cavity represents the magnetosphere. The red area denotes the region where a large amount of charged particles reside and intense electric currents flow within the magnetosphere. The four Cluster satellites encountered a flow reversal region in the magnetotail. Credit: Tony Lui, JHU/APL Something beneath the surface is changing Earth's protective magnetic field, which may leave satellites and other space assets vulnerable to high-energy radiation.
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6 J7 J/ j& c5 kThe gradual weakening of the overall magnetic field can take hundreds and even thousands of years. But smaller, more rapid fluctuations within months may leave satellites unprotected and catch scientists off guard, new research finds." ^9 s+ ^0 v$ r8 o, j, I; Z5 K
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A new model uses satellite data from the past nine years to show how sudden fluid motions within the Earth's core can alter the magnetic envelope around our planet. This represents the first time that researchers have been able to detect such rapid magnetic field changes taking place over just a few months.
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"There are these changes in the South Atlantic, an area where the magnetic field has the smallest envelope at one third [of what is] normal," said Mioara Mandea, a geophysicist at the GFZ German Research Center for Geosciences in Potsdam, Germany.- ~0 o. H: {( }1 |5 \9 R, w% ?/ Z# m
; g8 ?: @$ H- B9 Z7 k9 E5 WEven before the newly detected changes, the South Atlantic Anomaly represented a weak spot in the magnetic field — a dent in Earth's protective bubble.' a& k& p# U1 u5 u
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The Earth's magnetic field extends about 36,000 miles (58,000 km) into space, generated from the spinning effect of the electrically-conductive core that acts something like a giant electromagnet. The field creates a tear-drop shaped bubble that has constantly shielded life on Earth against much of the high-energy radiation flowing from the sun.; s H9 p! B/ ~9 E4 h5 g5 T& V
/ h/ S) |. s0 k+ @+ [0 ^" ?7 nThe last major change in the field took place some 780,000 years ago during a magnetic reversal, although such reversals seem to occur more often on average. A flip in the north and south poles typically involves a weakening in the magnetic field, followed by a period of rapid recovery and reorganization of opposite polarity.
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: B$ x& s) }% x3 `Some studies in recent years have suggested the next reversal might be imminent, but the jury is out on that question.- U) W7 O& m6 u$ a3 @
# @3 e Z1 T2 A1 HMeasuring interactions between the magnetic field and the molten iron core 1,864 miles (3,000 km) down has proven difficult in the past, but the constant observations of satellites such as CHAMP and Orsted have begun to bring the picture into focus.
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Mandea worked with Nils Olsen, a geophysicist at the University of Copenhagen in Denmark, to create a model of the fluid core that fits with the magnetic field changes detected by the satellites.
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) l# w# N0 J& i" N( ^7 u1 e; cHowever, the rapid weakening of the magnetic field in the South Atlantic Anomaly region could signal future troubles for such satellites. Radiation storms from the sun could fry electronic equipment on satellites that suddenly lacked the protective cover of a rapidly changing magnetic field.
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"For satellites, this could be a problem," Mandea told SPACE.com. "If there are magnetic storms and high-energy particles coming from the sun, the satellites could be affected and their connections could be lost."
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The constant radiation bombardment from the sun blows with the solar wind to Earth, where it flows against and around the magnetic field. The effect creates the tear-drop shaped magnetosphere bubble, but even the powerful field cannot keep out all the high-energy particles.% l L5 R" m/ W6 \7 D4 A( e3 e
1 V& A8 h8 b( @4 R& \8 s, eTopsy-turvy history
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A large sunspot set off a major radiation storm in 2006 that temporarily blinded some sun-watching satellites. Astronauts on the International Space Station retreated to a protected area as a precaution to avoid unnecessary radiation exposure.
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* S# z& Z( M* J8 ^5 vThe Earth's overall magnetic field has weakened at least 10 percent over the past 150 years, which could also point to an upcoming field reversal.8 W! k7 B& u% J, [& X! b
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Mandea and Olsen hope to continue refining their model with updated observations, and perhaps to eventually help predict future changes in the Earth's magnetic field.6 H- |6 f9 q2 q7 V
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The study was detailed in the May online edition of the journal Nature Geoscience.+ F+ @; q$ {3 C6 d: s5 b: W* [
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. _* N0 q: g8 W, z9 @+ Ohttp://www.livescience.com/space/080818-mm-earth-core.html
+ [0 c" D. w( M原文地址及网友评论+ B" ?( n( q: l% A7 F, U s
- D( c) g3 E5 z" S+ D1 hhttp://globalwarming-arclein.blo ... magnetic-field.html, |4 z0 g, D, W5 l/ Z
关于地球磁场
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! `: B8 U1 Y- ]% b# u6 Qhttp://www.lightworker.com/Science/?p=119) g( D/ G2 ^3 D/ g3 d* C0 w7 p
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