Solar wind . Stream of charged particles , ejected from the upper atmosphere of the Sun (or a star in general).
Summary
[ hide ]
- 1 General
- 2 Composition of the solar wind
- 3 Effects of the solar wind
- 1 Protection
- 2 Magnetic field of the solar wind
- 3 Solar wind vs. cosmic rays
- 4 Sources
Generals
This wind consists mainly of electrons and protons with energies generally between 10 and 100 keV. The particle flow varies in temperature and speed over time . These particles can escape from the gravity of the sun because of its high kinetic energy and the high temperature of the crown.
The solar wind creates the heliosphere , a huge bubble in the interstellar medium that surrounds the Solar System . Other phenomena are geomagnetic storms that can destroy power grids on Earth , auroras (northern and southern lights), and plasma from the tails of comets that always point away from the sun.
Composition of the solar wind
The elemental composition of the solar wind in the Solar System is identical to that of the solar corona: 73% hydrogen and 25% helium , with some traces of impurities. The particles are completely ionized , forming a very thin plasma. Near the Earth , the speed of the solar wind varies between 200 and 889 km / s, the average being about 450 km / s. The Sun loses approximately 800 kg of matter per second in the form of a solar wind.
Since the solar wind is plasma , it extends the solar magnetic field with it. At a distance of 160 million km, the solar rotation sweeps the solar wind in a spiral, dragging its magnetic field lines, but beyond that distance the solar wind is directed outward without further direct influence from the Sun. Unusually energetic bursts of solar wind caused by sunspots and other atmospheric phenomena from the Sun are called ” solar storms ” and can subject space probes and satellites to strong doses of radiation .
Solar wind particles that are trapped in the Earth’s magnetic field show a tendency to cluster in the Van Allen belts and can cause the Northern Lights and the Southern Auroras when they collide with the Earth’s atmosphere near the geographic poles. Other planets that have Earth-like magnetic fields also have their own auroras.
Effects of the solar wind
The solar wind forms a “bubble” in the interstellar medium ( gaseous hydrogen and helium in intergalactic space). The point at which the force exerted by the solar wind is not significant enough to displace the interstellar medium is known as a heliopause and is considered to be the outermost “edge” of the solar system. The distance to the heliopause is not precisely known and probably depends on the speed of the solar wind and the local density of the interstellar medium, but it is known to be well beyond Pluto’s orbit .
When the solar wind approaches a planet that has a well-developed magnetic field (such as Earth , Jupiter, and Saturn ), the particles are deflected by the Lorentz force. This region, known as the magnetosphere , prevents charged particles ejected by the Sundirectly impact the planet’s atmosphere and surface. The magnetosphere is more or less in the shape of a hemisphere on the side facing the Sun, and consequently a long trail forms on the opposite side, about 300,000 km long. The boundary of this region is called the magnetopause, and some of the particles are able to penetrate the magnetosphere through this region by partially reconnecting the lines of the magnetic field.
Protection
The Earth itself is protected from solar wind by its magnetic field , which deflects most of the charged particles, and most of those charged particles are trapped in the radiation belt Van Allen. The only time that the solar wind is observable on Earth is when it is strong enough to produce phenomena such as auroras and geomagnetic storms.
When this happens, brightly ionized auroras appear in the ionosphere, using plasma to expand in the magnetosphere, causing the plasma geosphere to increase in size, and the escape of atmospheric matter in the solar wind. Geomagnetic storms occur when the pressure of the plasma contained within the magnetosphere is large enough to inflate and therefore distort the electromagnetic field influencing communications of Radio and television .
Magnetic field of the solar wind
The solar wind’s magnetic field is responsible for the overall shape of Earth’s magnetosphere, and fluctuations in its speed, density, direction, and drag greatly affect the local environment in Earth’s space. For example, levels of ionizing radiation and radio interference can vary by factors of hundreds to thousands, and the shape and location of magnetopause and shock wave in the direct part of the sun can change the radius of the radiation several times. Earth, which can cause geostationary satellites to have direct exposure to the solar wind. These phenomena are collectively called space weather.
Solar wind vs cosmic rays
The solar wind affects incoming cosmic rays that interact with the planets atmosphere. On the other hand, planets with a weak or non-existent magnetosphere are subject to the exhaustion of their atmosphere by the solar wind. Venus , the closest and most Earth-like planet in our solar system, has an atmosphere 100 times denser than ours. Modern space probes have discovered a comet tail that stretches to the orbit of the Earth .
Mars is larger than Mercury , and is four times farther from the sun, and yet here the solar wind is thought to have removed up to a third of its original atmosphere, leaving a layer equal to 1/100 of Earth’s atmosphere . It is believed that the mechanism of this depletion is the atmosphere was forced into the bubbles of the magnetic field, which were later blown away by solar winds.
The Van Allen Belts protect the Earth from cosmic rays. However, there is an area called the South Atlantic Anomaly , which is a depression in the magnetic field. Greater radiation is registered in this area than in other sectors. And it only affects satellites that pass through this area.
Mercury , the planet closest to the Sun, receives the full force of solar winds, the atmosphere it has is residual and transitory, so its surface is always impacted by radiation. The Earth’s satellite, the Moon, has no atmosphere or intrinsic magnetic field, and consequently its surface is bombarded with all the force of the solar wind.
The Project Apollo missions and all of its tools were covered with expanded aluminum, and passive collectors were used in an attempt to access samples of lunar soil. When the mission returned and brought samples from the lunar surface, the study confirmed that the lunar regolith is rich in nuclei of the atoms deposited by the solar wind. It has been speculated that these elements may become useful resources for the future of the Moon’s colonies.
