Month: September 2023

Earth’s Magnetosphere and Plasmasheet

The Earth, surrounded by lines shooting out in many directions. They are labeled Interplanetary Magnetic Field Lines, which flow toward Earth. A bend in on of those lines is a Bow Shock. Lines looping out from Earth are labeled magnetosheath, magnetopause, magnetotail. Shaded areas billowing out from Earth are the Plasmasphere, Radiation Belts, and Plasma Sheet.
Our magnetosphere is part of a dynamic, interconnected system that responds to solar, planetary, and interstellar conditions – and it all starts deep inside Earth. Credit: NASA/Aaron Kaase

A magnetosphere is that area of space, around a planet, that is controlled by the planet’s magnetic field. The shape of the Earth’s magnetosphere is the direct result of being blasted by solar wind. The solar wind compresses its sunward side to a distance of only 6 to 10 times the radius of the Earth.

A supersonic shock wave is created sunward of Earth called the bow shock. Most of the solar wind particles are heated and slowed at the bow shock and detour around the Earth in the magnetosheath. The solar wind drags out the night-side magnetosphere to possibly 1000 times Earth’s radius; its exact length is not known. This extension of the magnetosphere is known as the magnetotail. The outer boundary of Earth’s confined geomagnetic field is called the magnetopause. The Earth’s magnetosphere is a highly dynamic structure that responds dramatically to solar variations.

Also residing within the magnetosphere are areas of trapped charged particles; the inner and outer Van Allen Radiation Belts, the plasmasphere, and the plasmasheet.

Layers of the Sun

The Sun, with layers labeled: Core, radiative zone, Convection zone, chromosphere, and corona. Features, including a solar prominent, subsurface flows, sunspots, flare, and a corona hole are labeled.
The Sun is a dynamic star, constantly changing and sending energy out into space. By studying our Sun, scientists can better understand the workings of distant stars. Credits: NASA

The Sun and its atmosphere consist of several zones or layers. From the inside out, the solar interior consists of:

  • The Core – the central region where nuclear reactions consume hydrogen to form helium. These reactions release the energy that ultimately leaves the surface as visible light.
  • The Radiative Zone – extends outward from the outer edge of the core to base of the convection zone, characterized by the method of energy transport – radiation.
  • The Convection Zone – the outermost layer of the solar interior extending from a depth of about 200,000 km to the visible surface where its motion is seen as granules and supergranules.

The solar atmosphere is made up of:

  • The Photosphere – the visible surface of the Sun.
  • The Chromosphere – an irregular layer above the photosphere where the temperature rises from 6000°C to about 20,000°C.
  • A Transition Region – a thin and very irregular layer of the Sun’s atmosphere that separates the hot corona from the much cooler chromosphere.
  • The Corona – the Sun’s outer atmosphere.

Beyond the corona is the solar wind, which is actually an outward flow of coronal gas. The Sun’s magnetic fields rise through the convection zone and erupt through the photosphere into the chromosphere and corona. The eruptions lead to solar activity, which includes such phenomena as sunspots, flares, prominences, and coronal mass ejections.

This infographic labels the parts of the Sun (from most inward to outward): Solar Core, Radiative Zone, Convection Zone, Photosphere, Chromosphere, Transition Zone, and Corona.It explains that the Sun's outermost layer is hotter than the layers immediately below that. This is a major unsolved puzzle in heliophysics.
At the heart of our solar system is the Sun. Even though the temperature of these layers is known, heliophysicists are still researching why the Sun’s corona, or atmosphere, is hotter than the layers immediately below it. Credits: NASA