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Results tagged with geomagnetism
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user 59023
Geomagnetism covers questions related to the Earth’s magnetic field, its origin, history and measurement. Use electromagnetism for more general questions on magnetism.
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How can auroras be visible at lower latitudes when a strong solar wind hits Earth?
The Earth's magnetic field is a tilted dipole and the side facing the Sun is compressed due to the incident solar wind. The anti-sunward side is stretched for reasons similar to why flags wave in the …
- 15.9k
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Why is aurora borealis circular in shape when viewed from space?
Why is aurora borealis circular in shape when viewed from space?
The aurora emissions you see are not actually circular, but rather oval shaped. They can look somewhat circular but they usually dis …
- 15.9k
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Why is Earth's magnetic field not strong?
Sure, the magnetic field magnitude of Earth, which forms the magnetosphere, is small compared to say, a good bar magnet. However, the magnetic moment of Earth is on the order of $\sim 8 \times 10^{22 …
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Is it generally accepted that Field Aligned Currents are caused by Force-Free Fields?
Is it generally accepted that Field Aligned Currents are caused by Force-Free Fields?
In a plasma, a force-free field is one that satisfies $\mathbf{j} \times \mathbf{B} = 0$, where $\mathbf{j}$ is …
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To what direction will a compass in a magnetic medium points? The direction of $B$-field or ...
The needle of a compass is, for all intents and purposes, a little dipole permanent magnet.
According to Jackson [1999], pages 184-190, the magnetic torque, $\mathbf{N}$, acting on a dipole magnetic m …
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Accepted
Is there any observable change in Earth's magnetism to an observer in geosynchronous orbit?
From what I understood, the magnetic field around the Earth exists because of the rotation of the Earth. The mantle consists of molten metallic ions, which, when they rotate in sync with the rotation …
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Description of Van Allen's Belt and Magnetic Mirrors
First, look at the answers at: https://physics.stackexchange.com/a/670591/59023 and https://physics.stackexchange.com/a/671056/59023.
The existence of the radiation belts results from the quasi-stabil …
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Accepted
How does the aurora brightness depend on the distance from the poles?
Both the Kp index 1, 2 and AE indices 3, 4, 5, 6 are indications of geomagnetic activity. However, auroral brightness depends upon the total number of oxygen and nitrogen atoms that are excited 7, 8, …
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How does the Earth's magnetic field protect it from the solar wind?
It has nothing to do with pressure in the thermodynamic sense nor with virtual particles. There is an intrinsic magnetic field generated somehow in Earth's core (dynamo discussion could fill volumes) …
- 15.9k
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Regarding the $\mathbf{E} × \mathbf{B} $ drift in the Earth's magnetic field
The only reason that the E x B drift doesn't generate an electric current is because both the electrons and the positive ions move towards the same direction...
The ExB-drift is independent of ch …
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Would the effects of a Coronal Mass Ejection be magnified in the South Atlantic Anomaly area?
This causes one of the weakest points of the Earth's magnetic field, and thus leads to an increased flux of energetic particles in this region.
No, the particles come closer to Earth's atmosphere …
- 15.9k
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Why is the top of the aurora red?
The aurora are caused by energetic electrons and protons impacting the atmosphere and exciting the atoms which then re-emit light. I have more background info in the following answer: https://physics …
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What did this geophysicist mean? (geomagnetism)
I always thought that the idea of a "line" of magnetic force was conceptual convenience, an artifice we used to be able to talk about magnetism but that there are no actual, physical discreet "line …
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Accepted
How would the Aurora light on Earth look like if there wasn't a magnetic field?
The aurora are emissions of light caused by the excitation of nitrogen and oxygen mostly by energetic (i.e., ~1 keV to few 10s of keV) electrons coming from the Earth's geomagnetic tail (i.e., anti-su …
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