The Strange Sounds of Earth's Auroral Kilometric Radiation
Δημοσιεύτηκε στις 9 Οκτ 2015
Earth
can generate radio emissions in a natural way. The most intense of
these emissions is a phenomenon called Auroral Kilometric Radiation
(AKR). It is produced in the auroral zones at an altitude between 3000
and 20 000 kilometres. The radiation mainly comes from cyclotron
radiation from electrons orbiting around the magnetic field lines of the
Earth. The radiation has a frequency of between 50 and 500 kHz and a
total power of between about 1 million and 10 million watts.
Afterwards,
the sounds escape outward into space in a concentrated direction from
the magnetic field lines but cannot be detected from the Earth's surface
as the ionosphere actually shields us from this radiation, hence only
at a height of about 3 times the radius of the Earth can AKR be
detected, as they were by solar, geomagnetic and plasma physics
satellites such as NASA's such as the Fast Auroral Snapshot Explorer
(FAST) missions and ESA's Cluster mission (from which this recording is
from).
AKR intensifies during magnetic and auroral substorms so
you can use it as a remote indicator of geomagnetic activity. The Wide
Band (WBD) instrument on-board Cluster recorded this sound and made the
first direct determination of the locations of an AKR (courtesy of Prof.
D. Gurnett, University of Iowa).
According to the data of the
Cluster mission, it is beamed out in the cosmos in a narrow,
concentrated beam plane tangent to the magnetic field at the source. The
sound produced by playing AKR over an audio device has been described
as "whistles", "chirps", and even "screams".
All planets with a
magnetic field produce AKR, with the gas giants such as Jupiter,
Saturn, Neptune and Uranus having the strongest given that they have the
largest internal magnetic fields. Interestingly, given the energy
concentrated in the radio band emitted being on the order of megawatts
and higher it might be possible to detect the AKR from planets beyond
the solar system, hence opening up new insights into the geomagnetism of
exoplanets and perhaps acting as another tool to narrow down the
physical conditions on them, such as whether they are solid or gaseous
or to simply say with evidence that their may be aurora in the skies of
an extra-solar planet which I think is a wondrous thought!
can generate radio emissions in a natural way. The most intense of
these emissions is a phenomenon called Auroral Kilometric Radiation
(AKR). It is produced in the auroral zones at an altitude between 3000
and 20 000 kilometres. The radiation mainly comes from cyclotron
radiation from electrons orbiting around the magnetic field lines of the
Earth. The radiation has a frequency of between 50 and 500 kHz and a
total power of between about 1 million and 10 million watts.
Afterwards,
the sounds escape outward into space in a concentrated direction from
the magnetic field lines but cannot be detected from the Earth's surface
as the ionosphere actually shields us from this radiation, hence only
at a height of about 3 times the radius of the Earth can AKR be
detected, as they were by solar, geomagnetic and plasma physics
satellites such as NASA's such as the Fast Auroral Snapshot Explorer
(FAST) missions and ESA's Cluster mission (from which this recording is
from).
AKR intensifies during magnetic and auroral substorms so
you can use it as a remote indicator of geomagnetic activity. The Wide
Band (WBD) instrument on-board Cluster recorded this sound and made the
first direct determination of the locations of an AKR (courtesy of Prof.
D. Gurnett, University of Iowa).
According to the data of the
Cluster mission, it is beamed out in the cosmos in a narrow,
concentrated beam plane tangent to the magnetic field at the source. The
sound produced by playing AKR over an audio device has been described
as "whistles", "chirps", and even "screams".
All planets with a
magnetic field produce AKR, with the gas giants such as Jupiter,
Saturn, Neptune and Uranus having the strongest given that they have the
largest internal magnetic fields. Interestingly, given the energy
concentrated in the radio band emitted being on the order of megawatts
and higher it might be possible to detect the AKR from planets beyond
the solar system, hence opening up new insights into the geomagnetism of
exoplanets and perhaps acting as another tool to narrow down the
physical conditions on them, such as whether they are solid or gaseous
or to simply say with evidence that their may be aurora in the skies of
an extra-solar planet which I think is a wondrous thought!
Κατηγορία
Άδεια
- Τυπική άδεια YouTube
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου