- #1
windy miller
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When we see the aurora moving rapidly are we effectively seeing the Earths Magnetic field moving ? Is that part of the explanation for the morphology of the aurora and why they never look quite the same?
Northern lights and the magnetic field
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- Thread starter windy miller
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In summary, the auroras are a result of collisions between particles from the solar wind and molecules in the atmosphere. These collisions are not random, but are influenced by the Earth's magnetic field and various other factors such as solar flares and coronal holes. The rapid movements of the aurora are not caused by the Earth's magnetic field moving, but rather by different mechanisms such as wave structures or instabilities in the upper ionosphere. Further research is still being conducted to fully understand the causes of different types of auroras.
- #2
stefan r
Science Advisor
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windy miller said:
I believe the particles are different. They enter the atmosphere at different velocity and from various angles.
- #3
rootone
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The Earth's magnetic field is not static unchanging, and the solar wind is not either.
- #4
windy miller
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rootone said:
So its a combination of both ?
- #5
thisisweak
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My understanding is that what you are seeing is collisions between oxygen molecules in the atmosphere and electrons and ions from a solar flair. What causes the pattern rather than just a random set of static like you would logically get I can not answer. Magnetism makes sense to me, since it mostly happens near the poles of the earth.
- #6
DrClaude
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The auroras come about from the collision of the solar wind with molecules in the atmosphere. The movement comes mostly from where the stream of solar wind particle hits. The aurora is not a direct visualisation of the Earth's magnetic field.
Source: https://www.sciencelearn.org.nz/images/247-solar-wind-plasma-and-the-magnetosphere
Source: https://www.sciencelearn.org.nz/images/247-solar-wind-plasma-and-the-magnetosphere
- #7
davenn
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2023 Award
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windy miller said:
Yes
rootone said:
Exactly, and this is particularly true when there are strong blasts of charged particles from the sun. The 2 main sources of these intense bursts of particles are from solar flares ( @thisisweak ) and from coronal holes.
The Solar wind is constantly spewing material into the surrounding space and in those conditions normally doesn't produce visible aurorae ( around the north and south poles) tho there can be weak radio aurora.
Coronal holes can produce minor to moderate geomagnetic storms. It's the significant solar flares M5 +++ with associated CME's ( Coronal Mass Ejections) that produce the moderate to major geomagnetic storms.
All significant pulses of particles from the sun cause the Earth's magnetic field to "flex" as those waves of particles push against it. and this is the main reason we see the waving motion in the auroral curtain.
Dave
- #8
jasonRF
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There are a number of different types of aurora, and the causes are still a very active area of research. A number of models have been proposed, and a fair amount of data has been collected as well. One of the challenges for gaining understanding is that we are lucky when we have even one spacecraft in the right place at the right time to measure what is going on above interesting auroral features that we see from the ground.
Some of the more rapid, small-scale dynamics of discrete auroral forms are often attributed to Alfven wave structures in the upper ionosphere (above 1000 km, say). These waves can have electric field components parallel to the geomagnetic field so can accelerate the electrons towards the Earth. The dynamics of the waves (incident from above) as they reflect from the upper ionosphere and/or interfere with each other and/or breakup due to instabilities can be complex. In this model the rapid change in the auroral arcs are a consequence of the parallel electric fields associated with those wave structures, not rapid movement of geomagnetic field lines. There have been measurements, including quite recently, of these kinds of wave structures above the aurora. The temporal and spatial scales associated with the waves correspond with relevant scales of auroral forms, and numerical simulations of these kinds of wave structures are also consistent.
Other types of observed auroral structures, such as auroral spirals, may be due to instabilities associated with the thin current sheets of downward-moving electrons. Some of the instabilities could create vortex-street like structures ("spirals") that you also see in other types of fluid motion.
I'm sure there are a number of other mechanisms as well, but I am not an expert in this field so don't know what-all is known. If you do a search on google scholar you should find many publications on this topic.
Jason
Some of the more rapid, small-scale dynamics of discrete auroral forms are often attributed to Alfven wave structures in the upper ionosphere (above 1000 km, say). These waves can have electric field components parallel to the geomagnetic field so can accelerate the electrons towards the Earth. The dynamics of the waves (incident from above) as they reflect from the upper ionosphere and/or interfere with each other and/or breakup due to instabilities can be complex. In this model the rapid change in the auroral arcs are a consequence of the parallel electric fields associated with those wave structures, not rapid movement of geomagnetic field lines. There have been measurements, including quite recently, of these kinds of wave structures above the aurora. The temporal and spatial scales associated with the waves correspond with relevant scales of auroral forms, and numerical simulations of these kinds of wave structures are also consistent.
Other types of observed auroral structures, such as auroral spirals, may be due to instabilities associated with the thin current sheets of downward-moving electrons. Some of the instabilities could create vortex-street like structures ("spirals") that you also see in other types of fluid motion.
I'm sure there are a number of other mechanisms as well, but I am not an expert in this field so don't know what-all is known. If you do a search on google scholar you should find many publications on this topic.
Jason
1. What causes the Northern Lights?
The Northern Lights, also known as Auroras, are caused by the interaction between charged particles from the Sun and the Earth's magnetic field. When these particles enter the Earth's atmosphere, they collide with gas particles and release energy in the form of light, creating the stunning displays we see in the sky.
2. How does the Earth's magnetic field affect the Northern Lights?
The Earth's magnetic field plays a crucial role in the formation of the Northern Lights. It acts as a protective shield, deflecting most of the charged particles from the Sun away from the Earth's surface. However, some particles are able to enter the magnetic field at the poles, where it is weaker, and travel towards the atmosphere, creating the Northern Lights.
3. Do the Northern Lights have any impact on the Earth's magnetic field?
Yes, the Northern Lights can have a small impact on the Earth's magnetic field. When the particles from the Sun interact with the Earth's magnetic field, they can cause fluctuations in the field's strength. However, these fluctuations are usually very small and do not have any significant effect on the Earth's overall magnetic field.
4. Where is the best place to see the Northern Lights?
The Northern Lights can be seen in the Northern Hemisphere, closer to the Earth's poles. The best places to see them are in areas with clear, dark skies, such as Alaska, Canada, Norway, and Iceland. The time of year also plays a role, with the best chances of seeing the Northern Lights being during the winter months.
5. Can the Northern Lights be predicted?
While there is no way to guarantee a sighting of the Northern Lights, they can be predicted to some extent. Scientists use data from satellites and ground-based observations to track the solar activity and predict when the Earth may be hit by a stream of charged particles. However, the intensity and location of the Northern Lights cannot be predicted with complete accuracy.
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