I've heard, like the sun, the earth's magnetic field is an essential energy source for all living things. If the earth's magnetic field no longer existed, how would this effect all life on our planet?\n\nWithout this form of energy, could it be responsible for ending all life as we know it? If so, how long would it take before our planet "died"?
133790
Well, the Earth's magnetic field has dropped to near zero many times in the past; whenever a magnetic reversal occurs, the magnetic field grows much weaker before it reverses polarity. It has been shown that the Earth went with only an extremely, extremely weak magnetic field for about 2000 years. Apparently, life was not too adversely affected by it; we still exist, and no extinction events coincided with the time frame. Therefore, the most we would have to worry about is the radiation we would recieve from the sun and space; an increase in skin cancers could be expected, though not much else.
504808
It does, but the Earth's magnetic field strength is very weak so the resulting emf is too small to be noticed.\n\nThe strength of the field at the Earth's surface ranges from less than 30 microteslas (0.3 gauss) in an area including most of South America and South Africa to over 60 microteslas (0.6 gauss) around the magnetic poles in northern Canada and south of Australia, and in part of Siberia.\n\nSo let's assume that we have a simple setup that can induce an EMF from Earth's magnetic field:\n\nEMF = -dΦ/dt, where Φ is the magnetic flux\n\nIf we consider a very simple case where Φ = BA, where B is the magnetic field and A is the surface area. So let's assume that\n\nB = 60 microTesla = 60 x 10^-6 Tesla or 0.00006 T\nA = 1 square meters\n\nand let the time duration of the manetic flux change be = 1 sec\n\nThen EMF = |-dΦ/dt| = BA/t = (0.00006)(1)/(1) = 0.00006 Volts\n\nAs you can see, I had to let the area of the magnetic flux be rather large (1 square meters). To see any sizable effect, we would actually need to consider much much bigger area, maybe like a square kilometer.
93455
In physics, a magnetic field is an entity produced by moving electric charges (electric currents) that exerts a force on other moving charges. (The quantum-mechanical spin of a particle produces magnetic fields and is acted on by them as though it were a current; this accounts for the fields produced by "permanent" ferromagnets.) A magnetic field is a vector field: it associates with every point in space a (pseudo-)vector that may vary in time. The direction of the field is the equilibrium direction of a compass needle placed in the field.
660500
pole\nmagnetic pole, the two nearly opposite ends of the planet where the earth's magnetic intensity is the greatest, as the north and south magnetic poles. For the magnetic north, it is the direction from any point on the earth's surface linking the horizontal component of the magnetic lines of force with the observer and north magnetic pole; it is similar for magnetic south. The north magnetic pole, first located (1831) by English explorer Sir James C. Ross, is now about 78°N and 104°W in the Queen Elizabeth Islands of northern Canada. The south magnetic pole, reached (1909) by English geologists Sir T. W. E. David and Sir Douglas Mawson, is now about 66°S and 139°E on the Adélie Coast of Antarctica. The magnetic poles are not fixed but follow circular paths with diameters of about 100 miles (160 km). Studies of paleomagnetism also indicate that the earth's magnetic field has reversed its polarity many times in the geologic past. The best hypothesis to date for the origin of terrestrial magnetism is the self-exciting dynamo theory, where the earth's magnetic field is generated by the interaction of motion and electrical currents in the earth's liquid outer core.\n\n///\nMagnetic fields are produced by the motion of electrical charges. For example, the magnetic field of a bar magnet results from the motion of negatively charged electrons in the magnet. The origin of the Earth's magnetic field is not completely understood, but is thought to be associated with electrical currents produced by the coupling of convective effects and rotation in the spinning liquid metallic outer core of iron and nickel. This mechanism is termed the dynamo effect. \nRocks that are formed from the molten state contain indicators of the magnetic field at the time of their solidification. The study of such "magnetic fossils" indicates that the Earth's magnetic field reverses itself every million years or so (the north and south magnetic poles switch). This is but one detail of the magnetic field that is not well understood\n\n....\nIn order to explain the fact that ferromagnetic materials with spontaneous magnetisation could exist in the demagnetised state Weiss proposed the concept of magnetic domains. Weiss built on earlier work carried out by Ampère, Weber and Ewing suggesting their existence. The findings of this work revealed that within a domain large numbers of atomic moments are aligned  typically 1012-1018, over a much larger volume than was previously suspected. The magnetisation within the domain is saturated and will always lie in the easy direction of magnetisation when there is no externally applied field. The direction of the domain alignment across a large volume of material is more or less random and hence the magnetisation of a specimen can be zero.\n\nMagnetic domains exist in order to reduce the energy of the system. A uniformly magnetised specimen as shown in figure 5(a) has a large magnetostatic energy associated with it. This is the result of the presence of magnetic free poles at the surface of the specimen generating a demagnetising field, Hd. From the convention adopted for the definition of the magnetic moment for a magnetic dipole the magnetisation within the specimen points from the south pole to the north pole, while the direction of the magnetic field points from north to south. Therefore, the demagnetising field is in opposition to the magnetisation of the specimen. The magnitude of Hd is dependent on the geometry and magnetisation of the specimen. In general if the sample has a high length to diameter ratio (and is magnetised in the long axis) then the demagnetising field and the magnetostatic energy will be low.\n\nThe break up of the magnetisation into two domains as illustrated in figure 5(b) reduces the magnetostatic energy by half. In fact if the magnet breaks down into N domains then the magnetostatic energy is reduced by a factor of 1/N, hence figure 5(c) has a quarter
574729
I swear I answer this question 4 or 5 times a week. \n\n1) Even without the moon we would still get tides. The tides are caused by both the sun and the moon equally. Solar tides would only be half as high as normal tides, and they would occur with a regular 12 hour rhythm rather than the monthly rhythm we get now.\n\n2) It would be almost impossible for complex life to survive without the moon. The moon locks the Earth into a stable position WRT the sun. As a result the equator always faces a the sun and the poles have always been perpendicular. Planets that lack large moons wobble, and at times the poles face the sun and the equator rotates perpendicular to the sun. At those times the temperature and light extremes would exterminate all complex life forms. \n\nWe don't know how long the Earth would remain in a perpendicular orientation  without the moon, but some time within the next half million years it would tip. When it did all surface life would die. Life would still be possible but every time the axis moved too far from perpendicular it would have to start afresh from deep sea bacteria.\n\n3) We have only one moon, and a very large moon, because it resulted from a collision AFTER the Earth had solidified. That collision tore off a huge chunk of the Earth and hurled it into orbit. In contrast the moons of other planets are either comets that have become trapped in orbit or were formed from the solar gas cloud BEFORE the planet itself formed.\n\nThe Earth's moon is unique in our solar system and is in no small part responsible for our evolution and continued existence.
637607
As far as magnetizing a seed is about harming it. magnetic field is as harm as Radioactive field. But magnetic field affect the growth of any living thing. One has not observed the effect of magnetic field. or not conducted any experiment with it. but to my experience. magnetic field too is hazadous
353190
Well, that's very interesting cuz if u think about it, if it's NOT alive but creates life (plants) than how could something dead create life???  How long could earth possibly live/survive without that glorious light?  Is the earth alive? Hmmmmmmmmmmm\n\nVery thought provoking, I'll have to put this question on my watch list!  It is an eternal source of power tho (like God).  So my answer must be yes than:o]
216000
I actually did hear about that in my college Astronomy class. I think it's pretty awesome. I mean, what if our sun burnt out. Maybe we could still have a significant amount of solar energy and radiation that could help us survive. I'm not sure if the star is old enough to develop life or not. It could have already developed it, and we just have no knowledge of it.
1381
Wikipedia has an excellent article on this.  According to them, there are 3 main theories:\n\n1. Asteroid collision\n\nBasically a huge rock hit our planet causing a plum of sediment to float into our atmosphere reducing light from the sun.  This reduction killed off a huge portion of the existing plant life, thus wiping out the food supply for many animals.  As one thing leads to another, massive extinctions followed.\n\n2. The Oort cloud\n\nSimilar to the asteroid theory, an Oort cloud is a literal storm of comets.  The results follow pretty closely with the single asteroid theory.\n\n3. Environment changes\n\nThis is a little more vague, but also a little simpler to prove to a degree (pun intended).  The theory follows the notion of the magnetic poles flipping (causing tremendous weather changes), or some other massive event (such as the melting of the caps, or an ice age) that would in turn kill off most of the larger species on the planet.\n\nFor further information, please read the wikipedia article.
566723
The earth's magnetic poles move constantly, and on some days the North magnetic pole moves by as much as 80 km (50 miles). To see a map of this go here:\nhttp://gsc.nrcan.gc.ca/geomag/nmp/daily_mvt_nmp_e.php\n\nThe short term wandering of the magnetic poles is caused by the Sun, which emits charged particles that disturb the Earth's magnetic field. Long term movement of the magnetic poles is due to changes within the Earth's molten core, which is thought to generate an electric field that in turn forms the magnetic field. At present the North Magnetic Pole is moving more than 40 km per year towards Siberia. To see the map:\nhttp://gsc.nrcan.gc.ca/geomag/nmp/long_mvt_nmp_e.php\n\nThe magnetic field of the Earth has undergone many complete reversals. The most recent reversal was about 730,000 years before present. Here is a timescale:\nhttp://gsc.nrcan.gc.ca/geomag/nmp/reversals_e.php\n\nIn addition to the reversals, the Earth's magnetic field has what are called excursions. These are wide variations in the strength of the field and in the direction of the magnetic force. On average, these excursions are less than 50,000 years in duration. \n\nThere have been many recorded episodes of climate change, both warming and cooling, over geologic time, and so far there has been no observed correlation between changes in the Earth's magnetic polarity or 'pole shift'  with any sort of climate change. There are some scientists that proposed that changes in the Sun's magnetic field might be causing an increase in Solar wind, which in turn would affect the Earth's atmosphere and might alter the cloud formation level. If this effect reduced lower level stratus clouds, it would cause global warming, but if it reduced high level cirrus clouds the effect would be cooling. However this possible climate effect caused by the Sun's magnetic field has nothing to do with Earth's magnetic field.
354947
I just saw a NOVA on this. One thing that was mentioned is that during the reversal, it's possible that for a period there would be 4 poles. There is evidence from rocks and computer models to support his. During this time, radiation would funnel into the lower latitudes where we, as a world, are heavily populated instead of the currently unpopulated poles. There would be an increase in cancer rates but not enough to be considered a "radiation epidemic". People in the lower latitudes would see the aurora borealis as well during this time as well - quite a bonus.\n\nCheck out http://www.pbs.org/wgbh/nova/magnetic/ for more information.
79327
I've heard it could cause health problems because of the electromagnetic energy. Doctors are also concerned because so many kids are using cell phones now. I only use mine when I have to. I really do hate them.
660820
Umm, your own source disputes your claim of no magnets:\n\nForm Wikipedia:\n\nObservations of the magnetic fields on Mars by the Mars Global Surveyor spacecraft have revealed that parts of the planet's crust have been magnetized. This magnetization has been compared to alternating bands found on the ocean floors of Earth. One theory, published in 1999 and reexamined in October 2005 with the help of the Mars Global Surveyor, is that these bands are evidence of the past operation of plate tectonics on Mars.[14]\n\nSo yes, a compass would work but not necessarily point to the north.
541192
Well, you are correct in that sittin' around will end in our collective lifes' destruction.  And attempts at proving life beyond Earth are ongoing.  Many of the missions to Mars are currently trying to prove that (among other things).  SETI is also an attempt to see or hear if anything is out there.  But that's a shot in the dark (har, har, de har har).\n\nThere are some significant steps being made to make spacecraft that can go "fast".  VASMIR (plasma rocket) among other things.\n\nThe two technologies that will drive us into the next level of abilities are quantum and nano technology.  Those will have significant impact on everything we build and contemplate.\n\nEventually our sun will get hotter, that could boil off our oceans (way before the sun bloats).  The Earths core could also cool enough that our magnetic field dissappears.  This would cause our atomosphere to slowly whisp away.\n\nBeing able to live in more hostile environments with nearly 100% recycling ability is our greatest challenge.  WIth that, we can start making our way out of this solar system and on to the next.\n\nWrite me for more discussion.  Fa shizzle.
203726
Earth's magnetic field constantly fluctuates to some degree (it's weakened by about 10% since the 19th Century), but the majority of geophysicists see no hard evidence that the field is about to reverse like it's done in the past.\n\nEven should it reverse, the whole cycle takes thousands of years, and still would have little effect on our electrical power systems. Nor would planes fall from the sky, although reliance on magnetic compasses would have to be adjusted.\n\nGod should be spelled B-I-G B-A-N-G\nPBrax@netscape.com
436830
The magnetic field of Earth is caused by molten iron rotating around in the core.  The lines of magnetic flux follow the right-hand rule (RHR).  Curve the fingers of your right hand into a loose fist and extend your thumb upward.\n\nAs the molten iron swirls around in the direction of your curled fingers, the flux is emitted in the direction of your extended thumb.  The flux is created because the swirling molten iron creates an electrical current that follows the swirl.  That current, like a current going through a coil, creates the magnetic flux.\n\nA flux is simply a line of force and that force, like all forces, has direction.  In this case, the force points outward in the direction of your thumb.  That's called the magnetic north pole, by convention.  \n\nHowever, because the magnetic flux exits the Earth at this pole it really is the south pole.  This can be verified because the north pole of a compass needle will point north and, as you well know, north is attracted to south.  Thus, the magnetic north pole is really the south pole...argh...physics is so complicated.\n\nAs to why like poles repel and dissimilar poles attract, blame in on the direction of the forces...the flux of that magnetic current.  (Magnetism does not really flow, but the forces act as though it does.)  Two similar poles either push each other away (e.g., two south poles) or pull away from each other (e.g., two north poles) because the forces are toward or away from the two magnets respectively.  Two dissimilar poles attract each other because the alligned forces pull one toward the other when they are all in the same direction.  [See source.]
674219
I don't think so. The Earths magnetic field is generated by the dynamo effect of the solid Ni-Fe core spinning at a different rate to the liquid Ni-Fe core around it. I can't see how humans can effect that process.\n\nI guess it might be possible to modify the magnetic field locally be producing another field that interferes with it....but I doubt we're doing anything strong enough to do that. The polar shift of the magnetic field is a natural process that has occurred thousands of times.\n\nTo answer 'my girls' question...the earths magnetic field protects us rather than harms us. If it didn't exist, we'd have little protection against the harmful radiation produced by our sun.