An Ecosystem of Magnetized Plasmas

Have you ever considered the fact that the Sun and the Earth are in direct communication? I mean yea it is obvious that the  ‘heat’ of the Sun effects life processes on this planetary sphere but what is that nebulous term ‘heat’ really when understood on the cosmic scale?

A plasma physicist from the University of Iowa, Jack Scudder, using observations from NASA’s THEMIS spacecraft and Europe’s Cluster Probing, has been researching a phenomenon which has many different names: x-points, electron diffusion regions or, and this is my personal favorite, magnetic portals [1]. A NASA article from July 2, 2012 stated that these portals are places where the magnetic field of Earth joins with the magnetic field of the Sun, creating an uninterrupted path leading from our planet to the Sun’s atmosphere 93 million miles away [ibid]. NASA has taken a serious interest in this body of knowledge and this researcher’s work. As of the data of that article NASA researchers were planning a mission called Magnetospheric –Multiscale Mission[2]. The focus of the mission will be to surround the portals with energetic particle detectors and magnetic sensors to observe how they work. Data is already available which demonstrates that these portals, which can be small and short lived to gigantic and sustained, open dozens of times a day[1]. When opened they allow a great deal of energetic exchange between the Sun and the Earth[2].

On planet Earth are an inconceivable number of lifeforms. Most are quite  far from the self-aware consciousness of homo-sapien, but I strongly believe that each is unique and conscious in its own way. Life on this scale would not be possible if it were not for one crucial factor – the magnetic field of the Earth. Without it creating layer upon layer of magnetized plasmas the solar wind would have long ago stripped away our atmosphere, including the oxygen so necessary for complex organisms[3]. What is the solar wind? How is the Earth’s magnetic field put together? And how do these phenomena interact?

Before elaborating on these phenomena I would like to take some time to focus on some interesting celestial mechanics that will affect the operation of this Sun-Earth system.

In the Northern Latitudes, starting in later March, a special point is reached called the vernal equinox. At this time the Sun is exactly perpendicular to the equator of Earth and as a result 12 hours of day and 12 hours of night occur as the Earth revolves around this location. Three months later the angle which the Sun’s rays hit the Northern Latitudes is at its maximum, which is termed the summer solstice. Later on there is an autumnal equinox and a winter solstice. When the winter solstice is reached the angle of declination of the sun is the same amplitude but it is now maximized in the opposite direction relative to the summer solstice.

apparent path of sun around earth

[4] Apparent path of the Sun from the Earth reference frame

The net effect of all these angles is that a magnetic field of similar strength (intensity) and direction will have very different effects on the planet at varying time periods during the year. Another way to visualize what I just said is the following: imagine you are holding two bar magnets.

MagneticMap_bar magnets[5] Bar magnet. Iron filing help illustrate the magnetic field lines. 

Both magnets will have a north and south pole or positive and negative ends. If you hold one steady and revolve another along a 30 degree angle you’ll notice that there are four significant points. Two points are when the center of the magnets are in the same horizontal plane and the other two will be when the magnets centers are maximally displaced from each other vertically. At these two points one of two things will occur: 1) the south pole of the stationary magnet is closer to the north pole of the revolving magnet or 2) the north pole of the stationary magnet is closer to the south pole of the revolving magnet. In a nutshell that is the Earth-Sun system and will explain a lot of the seasonal phenomena that we Earth Humans experience. But you did not come to this blog to get the super simple so let dive a bit deeper into this system.

Any investigation of the solar wind must first begin with the Corona (Spanish to English translation = crown) of the Sun. In much the same way that the Earth is layered from the lithosphere to the ionosphere to the magnetosphere, the Sun is also a layered construct. The corona is thousands of times higher, approximately 10 million times less dense than the surface of sol and contains extremely energetic particles [6]. Most astrophysicists are baffled by the energy gradient from the Sun’s surface to the corona [ibid]. Through the NASA mission IRIS comes one possible explanation. It was observed that “heat bombs” or in other words, spherical packets of high energy plasma, travel from the sun’s interior to the corona; when the conditions are right the packets explode, releasing heat in the process [7]. This newly introduced energy will accelerate the particles of the coronal layer to such speeds that the gravity of the Sun is no longer adequate to keep them bound to the sphere. This exodus of particles, whose mission it will be to traverse the solar system, are what astrophysicists have termed the solar wind.

What is so incredibly fascinating about this solar wind is that it is a plasmatic imprint of the Sun’s magnetic field [8]. Eventually this field will come into contact with Earth’s field and, if at the contact point Earth’s field is the opposite orientation or significantly different, then the lines of Earth’s field will break and reconnect to the whatever is attractive. Here is an explanation from a NASA site on the Magnetosphere Multiscale Mission:

” Magnetic fields serve as a “connective tissue” that binds plasmas together into cohesive cells sharing the same magnetic field lines. When different parts of a magnetized plasma cell move relative to each other, the magnetic field within it fights back and energy is stored in the stretched and deformed magnetic field. This energy is released when the plasma cell is divided by reconnection of the magnetic fields, disconnecting the magnetic linkage between the two regions in relative motion, and creating two distinct cells that are no longer linked, allowing the relative motion to proceed.”

This process is termed magnetic reconnection and effectively the Sun is converting magnetic energy to kinetic energy! [8,9]

As the solar wind approaches the Earth it comes into contact with a multitude of different plasmas, which are collectively termed the magnetosphere[10]. Breaking the magnetosphere into its major constituent layers yields the following domains: 1) the magnetopause 2) the Van Allen radiation belts 3) the plasmasphere and 4) the ionosphere. Shaped by the Earth’s magnetic fields as well as the impact of the solar wind, one will find highly energetic plasma consisting of free protons and electrons as well as ions of heavier elements emitted from the Sun in these layers [ibid]. The outer edge of this oval is 28 x RE (Earth Radius) at some places and an astonishing 200 x RE in other locations. According to the main function of the magnetosphere is to form an obstacle to the flow of the solar wind, oftentimes diverting it by approximately 11 RE.

Dipole_vs_Magnetosphere of Earth

[11] Earth’s magnetosphere: Interaction of Earth magnetic field with the solar wind. Visible are the outermost layers of the magentosphere. 

As we move from the interplanetary space towards the Earth’s core we next come across the magnetopause. This region exists at a distance of between 6 to 15 RE. Functionally, this layer acts as a sieve, allowing some particles carried by the solar wind to enter while rejecting others. One must recognize the dynamic nature of the outer magnetosphere and the magnetopause. While the magnetopause acts as a filter of solar-wind particles, it is very much affected by the composition and velocity of the solar wind.

In 1958 when the US satellite Explorer I was launched its first discovery was the Van Allen radiation belts. Originally two were discovered with a very pronounced null zone, which lacked electron presence. Since the 50’s it has been observed that the belts flux, merge and even separate into three bands. Between 600 and 9600 km above the Earth’s surface is the first belt and the second belt is bounded by the distance of 13500 to 58000 km (8.4 RE)[10]. The outer belt is quite the boundary. Unless there are strong winds or a coronal mass ejection of exceptional magnitude, even the fastest electrons cannot penetrate[ibid].

For the moment let’s proceed to the ionosphere and then we will return to a brief discussion of the plasmasphere. Many are in awe of the auroras produced within the high Northern Latitudes. What incredible sights these phenomena are! As I grow older I will travel extensively and to see these beauties with my own two eyes is something which I really desire. Norwegian plasma physicist and Nobel Laureate Hannes Alfvén proposed that Birkeland currents play a crucial role in “transmitting electromagnetic energy from the Sun to the Earth and in creating the auroras.” [ibid]. The theory goes that spiraling down electric field lines are 1-20 keV electrons and 200 keV ions which collide with particles in the ionosphere, exchanging energy in the process[ibid]. Those green emissions in the featured picture are oxygen excitations. Birkeland currents are theorized to be sheet-like. That being said, space and ground-based technology reveal a significantly more complex pattern of current flows in the ionosphere.

ionosphere currents

[ibid]. Currents projecting into and out of Earth’s ionosphere at the North magnetic pole connecting it to the plasmasphere and magnetospher

In 1963 both Grange and Carpenter using the Lunik Moon probes and propagating radio waves (Whistlers),respectively,  to identify a steep density gradient which corresponded to the outer plasmasphere [12]. The outer magnetosphere is hot, low-density plasma and the ionosphere is cool, high-density plasma[ibid]. The plasmasphere is located between these two regions. The temperature gradient is not continuous, as evidenced by the fact that the coldest plasma is in the plasmasphere according to NASA [13]. Torus-like in shape, the plasmasphere consists of closed, approximately dipolar electric field lines. This space can be dynamic and highly structured. [12]

When we think of the complexity of life we tend to anthropomorphize it. The development of a hominid brain from four nucleic acids that allows for interaction with the amorphous, cloud-like space of the internet or the Iphone is certainly astonishing. However I would argue that the development of relatively stable plasma differentials between fluxing magnetic and electrical fields which allows for timed physical cycles (i.e geomagnetic storms, climates, pole shifts) at regular intervals is pretty damn complex! In fact I would venture to say that the complexity of this cosmic ecosystem is many exponential factors removed from our own hominid complexity.


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