Content Enhancement
Adventures in Geospace
In addition to providing light and warmth, the Sun blows a million tons of matter into space every second. This matter is in the form of hot electrified material - mostly electrons and protons - in the fourth state of matter called plasma. This steady stream of matter called the solar wind travels through space at an average speed of 400km/s (900,000 miles/hr) with extremes from 300 km/s (700,000 miles/hr) to 900km/s (2 million miles/hr). Particularly energetic events on the Sun - sunspots, solar flares and coronal mass ejections (CME) - blast more particles into space. A typical CME can carry 10 billion tons of matter into space.
This constant barrage of fast moving, charged particles in the solar wind could be very dangerous to the Earth. However, in the 1930's Chapman and Ferraro modeled that the Earth's magnetic field provided a complete barrier to the plasma coming from the Sun. In the picture below, the solar wind (green), moving from left, is deflected by the magnetosphere (blue). The collision of the supersonically flowing solar wind with the magnetic field of the Earth forms a bow shock shown in red. The interaction of the shocked solar wind and the Earth's magnetic field forms what is known as the Magnetopause. The Magnetopause is the barrier to the solar wind.
Click on image to enlarge.
Although there is a barrier to the penetration of the solar wind plasma, some of its electrical energy does penetrate the Earth's magnetic shield. This is enough to generate millions of amps of electric current in the upper atmosphere, and can create occasional magnetic storms. Very energetic events like Coronal Mass Ejections can create spectacular auroras, damage satellites, disrupt radios, burn out power transformers and corrode pipelines. Obviously, the magnetosphere is not an impermeable magnetic shield. In the 1960's James Dungey provided a mechanism by which the solar wind and its imbedded magnetic field couple to the Earth's magnetosphere. This mechanism he called magnetic reconnection. Recent satellite missions, many of which flew under the International Solar Terrestrial Physics Program (ISTP), have gathered data that have allowed scientists to build upon Dungey's theories. The new picture of the solar-terrestrial interactions is more complex. Powerful new models have been constructed. Four of the Solar Terrestrial Probes (STP) missions, Thermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED), Magnetospheric Multiscale Mission (MMS), Geospace Electrodynamics Connection (GEC) and Magnetospheric Constellation (MC) will gather important information about the dynamic structure of the magnetosphere and its affect upon the upper atmosphere of Earth. But first it is important to know about Electricity, Magnetism, Electromagnetism and how the Earth becomes A Magnet in Space.
- NASA Official: Dr. James Thieman
- Project Manager: Don Robinson-Boonstra
- Website Manager: Bryan Stephenson