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Very weak electromagnetic fields disrupt the magnetic compass used by European robins and other songbirds, which use the Earth's magnetic field to navigate. Neither power lines nor cellphone signals are to blame for the electromagnetic field effect on the birds; [ 89 ] instead, the culprits have frequencies between 2 kHz and 5 MHz.
Earth's_magnetic_field,_schematic.png (566 × 503 pixels, file size: 96 KB, MIME type: image/png) This is a file from the Wikimedia Commons . Information from its description page there is shown below.
The magnetic field of a magnetic dipole has an inverse cubic dependence in distance, so its order of magnitude at the earth surface can be approximated by multiplying the above result with (R outer core ⁄ R Earth) 3 = (2890 ⁄ 6370) 3 = 0.093 , giving 2.5×10 −5 Tesla, not far from the measured value of 3×10 −5 Tesla at the equator.
Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that the magnetic field on the surface of Earth resembled that of a terrella, a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory , which attributes Earth's magnetic field to the motion of Earth's iron outer core .
An electromagnetic field (also EM field) is a physical field, mathematical functions of position and time, representing the influences on and due to electric charges. [1] The field at any point in space and time can be regarded as a combination of an electric field and a magnetic field .
Images featured on the Astronomy Picture of the Day (APOD) web site may be copyrighted. The National Space Science Data Center (NSSDC) site has been known to host copyrighted content. Its photo gallery FAQ states that all of the images in the photo gallery are in the public domain "Unless otherwise noted."
Certified astrophysicist and Star Wars fan Jeanne Cavelos explains that scientists have been skeptical about the likelihood of binary star systems such as Tatooine since the gravity of one star may prevent planets from developing around the other. Two stars of different masses orbiting one another would cause gravity fields to shift, causing ...
Map of the Star Wars galaxy (Legends). The Star Wars galaxy contains several broad sub-regions. Their exact definitions fluctuated somewhat during the Legends continuity, but were later formally updated by the new canon continuity when Disney purchased Lucasfilm.