Auroral kilometric radiation (AKR) is the intense radio radiation emitted in the acceleration zone (at a height of three times the radius of the Earth) of the polar lights. 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. The radiation is absorbed by the ionosphere and therefore can only be measured by satellites positioned at vast heights, such as the Fast Auroral Snapshot Explorer (FAST). According to the data of the Cluster mission, it is beamed out in the cosmos in a narrow plane tangent to the magnetic field at the source. The sound produced by playing AKR over an audio device has been descri
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| - Auroral kilometric radiation (en)
- Radiazione chilometrica aurorale (it)
- Rayonnement kilométrique auroral (fr)
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| - La radiazione chilometrica aurorale (AKR) è l'emissione intensa di onde radio, dovuta alla radiazione di ciclotrone degli elettroni, che ruotano attorno alle linee di forza del campo magnetico terrestre. La radiazione emessa ha frequenza fra i 50 e 500 kHz, mentre l'energia totale emessa va da circa 1 milione a 10 milioni di Watt. Tale radiazione non può essere misurata da terra poiché la ionosfera riflette tali onde radio. Il motivo di ciò è dovuto al fatto che la ionosfera è costituita da plasma, il quale non è trasparente a onde elettromagnetiche a frequenze inferiori ai 50 MHz. (it)
- Auroral kilometric radiation (AKR) is the intense radio radiation emitted in the acceleration zone (at a height of three times the radius of the Earth) of the polar lights. 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. The radiation is absorbed by the ionosphere and therefore can only be measured by satellites positioned at vast heights, such as the Fast Auroral Snapshot Explorer (FAST). According to the data of the Cluster mission, it is beamed out in the cosmos in a narrow plane tangent to the magnetic field at the source. The sound produced by playing AKR over an audio device has been descri (en)
- Le rayonnement kilométrique auroral (en anglais, auroral kilometric radiation ou AKR) est généré au-dessus de la Terre par les mêmes particules solaires qui produisent les aurores boréales et australes. Découvert par les satellites dans les années 1970, le rayonnement kilométrique auroral était passé jusque-là inaperçu car bloqué par l'ionosphère. En analysant plus de 12000 AKR, une équipe de scientifiques a constaté que leurs signaux se diffusaient sur une bande de fréquence extrêmement étroite, et non comme un cône d'émission s'élargissant, ainsi que le pensaient précédemment les chercheurs. (fr)
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| - Auroral kilometric radiation (AKR) is the intense radio radiation emitted in the acceleration zone (at a height of three times the radius of the Earth) of the polar lights. 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. The radiation is absorbed by the ionosphere and therefore can only be measured by satellites positioned at vast heights, such as the Fast Auroral Snapshot Explorer (FAST). According to the data of the Cluster mission, it is beamed out in the cosmos in a narrow 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". As some other planets emit cyclotron radiation too, AKR could be used to learn more about Jupiter, Saturn, Uranus and Neptune, and to detect extrasolar planets. (en)
- Le rayonnement kilométrique auroral (en anglais, auroral kilometric radiation ou AKR) est généré au-dessus de la Terre par les mêmes particules solaires qui produisent les aurores boréales et australes. Découvert par les satellites dans les années 1970, le rayonnement kilométrique auroral était passé jusque-là inaperçu car bloqué par l'ionosphère. En analysant plus de 12000 AKR, une équipe de scientifiques a constaté que leurs signaux se diffusaient sur une bande de fréquence extrêmement étroite, et non comme un cône d'émission s'élargissant, ainsi que le pensaient précédemment les chercheurs. Aujourd'hui (2009), les scientifiques sont capables de déterminer exactement le point d'origine de ce rayonnement grâce aux 4 satellites de la mission Cluster de l'Agence spatiale européenne qui, volant en formation, triangulent leurs positions comme le font les satellites GPS. La Terre n'est pas la seule planète du système solaire à en émettre. Jupiter et Saturne sont également le siège d'un tel phénomène. C'est l'une des émissions naturelles les plus puissantes de la Terre. Ce signal serait facilement détectable par une éventuelle civilisation extraterrestre. De la même façon, il pourrait également être utilisé pour détecter d'autres planètes extrasolaires, bien que les instruments actuels soient encore trop peu sensibles pour le faire. (fr)
- La radiazione chilometrica aurorale (AKR) è l'emissione intensa di onde radio, dovuta alla radiazione di ciclotrone degli elettroni, che ruotano attorno alle linee di forza del campo magnetico terrestre. La radiazione emessa ha frequenza fra i 50 e 500 kHz, mentre l'energia totale emessa va da circa 1 milione a 10 milioni di Watt. Tale radiazione non può essere misurata da terra poiché la ionosfera riflette tali onde radio. Il motivo di ciò è dovuto al fatto che la ionosfera è costituita da plasma, il quale non è trasparente a onde elettromagnetiche a frequenze inferiori ai 50 MHz. (it)
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