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There's no reason to think that the Earth was ever without a magnetic "shield," except perhaps in its frequent but short periods of reversal of magnetic polarity, from the time the Earth's basic structure formed down to the present day.
When magma cools and solidifies to form igneous rocks, some of the minerals may preserve a record of the magnetic field strength and direction at that time. From this, scientists have been able to construct a record of field strengths and geomagnetic reversals going back at least 160 million years. Therefore we have good proof that the magnetic field has been around for at least that long.
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∙ 15y ago
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∙ 15y agoIn its entirety, until the core stops its circulation. In its current plane, it is interesting to note that the axis of the magnetic field can shift and even reverse over millions of years. Though infrequent in occurrence, scientists have determined that the shift itself occurs fairly rapidly (estimates over 10 years). Should the magnetic field stop, earth's protection against effects from solar radiation and ionizing particles would be gone. It is likely that the atmosphere would be ionized and degraded, thus allowing no breathable air left.
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∙ 9y agoMagnetic epochs last a long period of time, geologically. It is when the earth's magnetic field is the same polarity.
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∙ 12y agoAccording to current theories, when the Earth's core is no longer molten.
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∙ 15y agoAnywhere between 10,000 and 25,000 years.
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∙ 14y ago10.5
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∙ 12y ago25
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How strong is the sun's magnetic field?
Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole, with the magnetic field South pole near the Earth's geographic north pole (see Magnetic North Pole) and the other magnetic field N pole near the Earth's geographic south pole (see Magnetic South Pole). This makes the compass usable for navigation. The cause of the field can be explained by dynamo theory. A magnetic field extends infinitely, though it weakens with distance from its source. The Earth's magnetic field, also called the geomagnetic field, which effectively extends several tens of thousands of kilometres into space, forms the Earth's magnetosphere. A paleomagnetic study of Australian red dacite and pillow basalt has estimated the magnetic field to be at least 3.5 billion years old.
How often does the sun have a pole reversal?
Every 22 years.
Hopw many magnetic fields does Mars have?
Mars does not have a global magnetic field like Earth does. It has remnants of and old global field that may have disappeared 500 million years ago. That would have been the end of protection against the solar wind. It would have stripped the atmosphere off and fried most land life.
if earth was not spinning there would be no?
Diurnal cycle
How do scientists know that the earths magnetic poles have reversed themselves many times during earths history?
The answer lies in ocean basalts. As the sea floor slowly spreads, the igneous rock of which it is comprised cools and congeals, recording earth's current magnetic pole alignment. It turns out there are numerous parallel stripes encoded within ocean bedrock, indicating the strength and polarity of earth's magnetic field over the course of many millions of years. One trouble with this record is that once the sea floor reaches a continental plate margin it is subducted beneath the crustal rock and destroyed, so the record is only about a hundred million years old at most.However, there is excellent agreement between the sea floor rock and volcanic rock deposited on earth's surface. We can date isotopes within that rock to compare the sea floor record with the record on land, and confirm the accuracy of the dating techniques. One fascinating find is known as the Jaramillo Creek event, a pole reversal from about 900,000 years ago.
How many year marks the reversal of the sun's magnetic field?
11 years.
When was the most recent reversal of the earth's magnetic field?
As stated in Wikipedia: "The last reversal was theBrunhes-Matuyama reversal approximately 780,000 years ago."
What Is The Difference Between Magnetic reversal reversed field and normal field?
A magnetic reversal happens in a magnetic field generated naturally in a spinning object such as the Earth or the Sun. In cases where the magnetic field is generated as a result of spin the polarity of the field (where the north and south poles are) flips on a regular periodic basis. For instance about once every 11 years on the Sun and about every 100 thousand years on the Earth. This flipping of the field is called a 'magnetic reversal' on Earth and a solar cycle on the Sun. Between flipping events the magnetic field of the body is regular or normal (but of cause in the opposite orientation each flip) but during the flipping process the field is chaotic with many minor polar regions appearing round the body (as sunspots during a solar maxima) and presumable a similar but slower thing happens on Earth (we do not know yet but it looks as though the Earth's poles may be beginning to reverse at the moment).
When was the last known magnetic pole reversal?
Roughly 750,000 years ago.
Earths magnetic poles reverse approximately every years?
The process of the reversal of the Earth's magnetic poles is called a magnetic flip. This occurs every 4 or 5 times per million years.
What are the earth polar shifts?
A geomagnetic reversal is a change in the orientation of Earth's magnetic field such that the positions of magnetic north and magnetic south become interchanged. These events often involve an extended decline in field strength followed by a rapid recovery after the new orientation has been established. These events occur on a scale of tens of thousands of years or longer.more info herehttp://en.wikipedia.org/wiki/Geomagnetic_reversal
What if earth's magnetic field did not occasionally reverse polarity?
We expect Earth would still have a magnetic field during a reversal, but it would be weaker than normal with multiple magnetic poles. Radio communication would deteriorate, navigation by magnetic compass would be difficult and migratory animals might have problems. Many migratory animals use the geomagnetic field to orient themselves. However, even if Earth's magnetic field began a reversal, it would still take several thousand years to complete a reversal.
How old is the magnetic field?
The Sun is 4.5 billion years old and as everything has a magnetic field it stands to reason that it also is 4.5 billion years old.
What are reversals?
In the past, the polarity of the Earth's magnetic field has reversed, many times over. This was discovered in samples of the rocks of the ocean floor at mid-ocean ridges, where matching patterns of magnetic polarity were discovered on each side of the mid ocean ridge. It is believed that the magnetic field is caused by electrical currents in the Earth's interior. [We know that the interior is too hot to sustain the magnetism of a bar magnet. As proved by the Curie's.] If these currents circulate parallel to the equator, then they would be pretty stable. but we know that the poles are moving. This may indicate that the path of electrical conduction is not a simple circle. We just have to wait. The earth's magnetic field is caused by the effect of the Earth's rotation on the liquid iron core. This field occasionally flips so that the direction that was magnetic north becomes magnetic south and what was magnetic south becomes magnetic north. This is called a magnetic reversal and these reversals can be detected in Earth's lava rocks which lock in the direction of the current field when they cool and solidify. Earth's magnetic field flips about once every 100 thousand years. The Sun goes through similar magnetic reversal cycles but on the Sun the reversals happen about once every 11 years. Please see the related link for more information.
Has the magnetic field of the earth ever flipped?
There has been a lot of confusion about this. It depends if your asking about a geomagnetic reversal, or the other on. It has been forseen that there may be a geomagnetic reversal some time in the very near future, namely 2012. I think this is very true. See the Mayan callender which ends in 2012, in December. Apparently a geomagnetic polar shift will bring calamatity and death to earth,
How old is the sun's magnetic field?
The Sun is 4.5 billion years old and as everything has a magnetic field it stands to reason that it also is 4.5 billion years old.
What is the estimated time for a magnetic reversal to occur?
In the sun, the cycle corresponds with the cycle of visible sunspot numbers, and is roughly 11 years. In the Earth, the cycle of magnetic reversal appeares to be very irregular, with periods anywhere between 200,000 and 400,000 years. In both cases, the reversal is not something that happens suddenly at, say, 11:36 one morning. It happens gradually and continuously. For something to compare it to, think of a wave on the lakeshore ... Is the wave in, or is it out ? It's changing smoothly between the two extremes. Similarly, both the sun and the Earth are in the process of magnetic reversal right now.
