Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.
Could magnetic reversals be caused by meteorite or comet impacts?
Although extremely unlikely, it might be possible for a reversal of the Earth's magnetic field to be triggered by a meteorite or comet impact, or even for it to be caused by something more "gentle," such as the melting of the polar ice caps.
Self-contained dynamic systems like Earth’s dynamo can have reversals without any outside influence. Reversals of Earth's magnetic field can simply happen.
Learn more: USGS Geomagnetism Program
Related Content
Do any mass extinctions correlate with magnetic reversals?
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
How can I tell if I have found an impact crater?
There are many natural processes other than impacts that can create circular features and depressions on the surface of the Earth. Examples include glaciation, volcanism, sinkholes, atolls, salt domes, intrusions, and hydrothermal explosions (to name just a few). Prehistoric mines and quarries are also sometimes mistaken for impact craters. Although the USGS has been involved in impact crater...
Why measure the magnetic field at the Earth's surface? Wouldn't satellites be better suited for space-weather studies?
Satellites and ground-based magnetometers are both important for making measurements of the Earth’s magnetic field. They are not redundant but are instead complementary: Satellites provide good geographical coverage for data collection. Ground-based magnetometers are much less expensive and much easier to install than satellites. An array of magnetometers provides coverage from numerous locations...
Does the Earth's magnetic field affect human health?
The Earth's magnetic field does not directly affect human health. Humans evolved to live on this planet. High altitude pilots and astronauts can experience higher levels of radiation during magnetic storms, but the hazard is due to the radiation, not the magnetic field itself. Geomagnetism can also impact the electrically based technology that we rely on, but it does not impact people themselves...
Are we about to have a magnetic reversal?
Almost certainly not. Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those same paleomagnetic records also show that the field...
How does the Earth's core generate a magnetic field?
The Earth's outer core is in a state of turbulent convection as the result of radioactive heating and chemical differentiation. This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic energy is converted to electrical and magnetic energy. Basically, the motion of the electrically conducting iron in the presence of the Earth's magnetic...
Is the Earth a magnet?
In a sense, yes. The Earth is composed of layers having different chemical compositions and different physical properties. The crust of the Earth has some permanent magnetization, and the Earth’s core generates its own magnetic field, sustaining the main part of the field we measure at the surface. So we could say that the Earth is, therefore, a "magnet." But permanent magnetization cannot occur...
Is it true that Earth's magnetic field occasionally reverses its polarity?
Yes. We can see evidence of magnetic polarity reversals by examining the geologic record. When lavas or sediments solidify, they often preserve a signature of the ambient magnetic field at the time of deposition. Incredible as it may seem, the magnetic field occasionally flips over! The geomagnetic poles are currently roughly coincident with the geographic poles, but occasionally the magnetic...
Gale crater
Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.
Hazards: Geomagnetic Storms
Space weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation.
By
Space weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation.
By
Earth Science Week, Continued: Geomagnetism and the Self-Sustaining Dynamo Called Earth
USGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.
USGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.
Cratered cones near Hephaestus Fossae
Cratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape.
Cratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape.
PubTalk 3/2007 — Impact!
Piecing together the story of a giant meteorite crater beneath the Atlantic coast
By David S. Powars, Geologist, and R.D. Catchings, Geophysicist
Piecing together the story of a giant meteorite crater beneath the Atlantic coast
By David S. Powars, Geologist, and R.D. Catchings, Geophysicist
PubTalk 7/2004 — Secrets in Stone
The Role of Paleomagnetism in the Evolution of Plate Tectonic Theory Video Presentation
Presentation of the award-winning USGS video "Secrets in Stone" (35 minutes), introduced by Jack Hillhouse, Research Geophysicist, and followed by a tour of the USGS Paleomagnetics Laboratory
The Role of Paleomagnetism in the Evolution of Plate Tectonic Theory Video Presentation
Presentation of the award-winning USGS video "Secrets in Stone" (35 minutes), introduced by Jack Hillhouse, Research Geophysicist, and followed by a tour of the USGS Paleomagnetics Laboratory
Related Content
- FAQ
Do any mass extinctions correlate with magnetic reversals?
No. There is no evidence of a correlation between mass extinctions and magnetic pole reversals. Earth’s magnetic field and its atmosphere protect us from solar radiation. It’s not clear whether a weak magnetic field during a polarity transition would allow enough solar radiation to reach the Earth's surface that it would cause extinctions. But reversals happen rather frequently--every million...
How can I tell if I have found an impact crater?
There are many natural processes other than impacts that can create circular features and depressions on the surface of the Earth. Examples include glaciation, volcanism, sinkholes, atolls, salt domes, intrusions, and hydrothermal explosions (to name just a few). Prehistoric mines and quarries are also sometimes mistaken for impact craters. Although the USGS has been involved in impact crater...
Why measure the magnetic field at the Earth's surface? Wouldn't satellites be better suited for space-weather studies?
Satellites and ground-based magnetometers are both important for making measurements of the Earth’s magnetic field. They are not redundant but are instead complementary: Satellites provide good geographical coverage for data collection. Ground-based magnetometers are much less expensive and much easier to install than satellites. An array of magnetometers provides coverage from numerous locations...
Does the Earth's magnetic field affect human health?
The Earth's magnetic field does not directly affect human health. Humans evolved to live on this planet. High altitude pilots and astronauts can experience higher levels of radiation during magnetic storms, but the hazard is due to the radiation, not the magnetic field itself. Geomagnetism can also impact the electrically based technology that we rely on, but it does not impact people themselves...
Are we about to have a magnetic reversal?
Almost certainly not. Since the invention of the magnetometer in the 1830s, the average intensity of the magnetic field at the Earth's surface has decreased by about ten percent. We know from paleomagnetic records that the intensity of the magnetic field decreases by as much as ninety percent at the Earth's surface during a reversal. But those same paleomagnetic records also show that the field...
How does the Earth's core generate a magnetic field?
The Earth's outer core is in a state of turbulent convection as the result of radioactive heating and chemical differentiation. This sets up a process that is a bit like a naturally occurring electrical generator, where the convective kinetic energy is converted to electrical and magnetic energy. Basically, the motion of the electrically conducting iron in the presence of the Earth's magnetic...
Is the Earth a magnet?
In a sense, yes. The Earth is composed of layers having different chemical compositions and different physical properties. The crust of the Earth has some permanent magnetization, and the Earth’s core generates its own magnetic field, sustaining the main part of the field we measure at the surface. So we could say that the Earth is, therefore, a "magnet." But permanent magnetization cannot occur...
Is it true that Earth's magnetic field occasionally reverses its polarity?
Yes. We can see evidence of magnetic polarity reversals by examining the geologic record. When lavas or sediments solidify, they often preserve a signature of the ambient magnetic field at the time of deposition. Incredible as it may seem, the magnetic field occasionally flips over! The geomagnetic poles are currently roughly coincident with the geographic poles, but occasionally the magnetic...
- Multimedia
Gale crater
Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.
Infrared mosaic image of Mars Gale crater by the Thermal Emission Imaging Spectrometer (THEMIS) of the USGS Astrogeology Science Center and Arizona State University. The Mars Science Laboratory is scheduled to land in Gale crater Aug. 5, 2012.
Hazards: Geomagnetic StormsSpace weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation.
BySpace weather can have important consequences for our lives, such as interference with radio communication, GPS systems, electric power grids, the operation and orientation of satellites, oil and gas drilling, and even air travel as high altitude pilots and astronauts can be subjected to enhanced levels of radiation.
ByEarth Science Week, Continued: Geomagnetism and the Self-Sustaining Dynamo Called EarthUSGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.
USGS scientist Duane Champion explains the Earth's geomagnetic qualities and the potential for and possible consequences of a geomagnetic shift.
Cratered cones near Hephaestus FossaeCratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape.
Cratered cones near Hephaestus Fossae, Mars. This might look at first glance like a cinder cone, but it is more likely an impact crater. Using the shadow, one can tell that its floor is at a lower elevation than the surrounding landscape. A cinder cone would rise above the landscape.
PubTalk 3/2007 — Impact!Piecing together the story of a giant meteorite crater beneath the Atlantic coast
By David S. Powars, Geologist, and R.D. Catchings, Geophysicist
Piecing together the story of a giant meteorite crater beneath the Atlantic coast
By David S. Powars, Geologist, and R.D. Catchings, Geophysicist
PubTalk 7/2004 — Secrets in StoneThe Role of Paleomagnetism in the Evolution of Plate Tectonic Theory Video Presentation
Presentation of the award-winning USGS video "Secrets in Stone" (35 minutes), introduced by Jack Hillhouse, Research Geophysicist, and followed by a tour of the USGS Paleomagnetics Laboratory
The Role of Paleomagnetism in the Evolution of Plate Tectonic Theory Video Presentation
Presentation of the award-winning USGS video "Secrets in Stone" (35 minutes), introduced by Jack Hillhouse, Research Geophysicist, and followed by a tour of the USGS Paleomagnetics Laboratory
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