The massive amounts of energy emitted by a typical solar flare radiate mostly far into the ultraviolet and X-ray portion of the electromagnetic (EM) spectrum, at shorter wavelengths and with higher energies than visible light. Solar flares can heat nearby materials in the sun’s atmosphere, releasing huge clumps of plasma to Earth in what’s known as coronal mass ejections.
Earth’s atmosphere filters out most of these wavelengths, so satellites and specialized instruments aboard spacecraft are the main ways scientists detect high-energy radiation from flares. However, the visible light component of the glow can be seen from Earth using specialized solar-monitoring telescopes that filter all but a narrow band of wavelengths. In rare cases, strong flares can even be observed as intense star-like points of light that project once morest the sun’s disk when viewed through a safe projection through a telescope, according to the American Astronomical Society.
“Solar flares are classified according to how bright they are in soft X-rays,” Stephanie Yardley, a space weather specialist at the Mullard Space Science Laboratory at University College London in the United Kingdom, told Live Science. “The weakest flares are class A or B, while the strongest flares are.” Class C, M or X. Each letter represents an increase in power by a factor of 10 and in each class there is a numerical scale from 1-9. The largest event recorded was the Carrington event in 1859 [الذي سمي على اسم عالم الفلك الإنجليزي ريتشارد كارينغتون، الذي رصده بالصدفة أثناء مراقبة الشمس] which has a peak soft X-ray of X45. The second most powerful event was the X35 class solar flare on November 4, 2003.
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Flares form in regions where rings of the magnetic field pass through the solar atmosphere. These rings are generated by ripples of plasma (hot, electrically charged gas) inside the sun and thrust out across the surface. Cooler regions around entry and exit points appear as dark sunspots amid the hotter and brighter gas, while the rings also transmit relatively cool gas along them, appearing as dark “filaments” when placed in silhouette once morest the photosphere, or as pinkish protrusions around the edge or One of the ends of the sun (better visible during a total solar eclipse).
The glow occurs when the lower regions of the magnetic ring become held together in a region of the atmosphere called the corona. This leads to a “short circuit” of the magnetic field. And because a magnetic ring high above the surface carries much more energy than one below, these reconnections can release a huge amount of excess energy. This heats the solar atmosphere around the reconnection point to temperatures of 50 to 68 million degrees Fahrenheit (10 to 20 million degrees Celsius), much hotter than the 2 million Fahrenheit (1 million Celsius) as usual, causing in the emission of a violent wave of radiation.
Astronomers use the term “flare” specifically for the burst of energy and radiation on the Sun, but it is associated with a variety of other effects. For example, material from the solar atmosphere heated by the flare can begin to expand violently, eventually forming a coronal mass ejection, or CME – a huge cloud of particles exploding in a particular direction, which can take several days to reach Earth’s orbit.
The most violent flares also produce an effect called a solar proton storm, in which the shock from the expansion of the CME accelerates nearby protons (subatomic charged particles), pushing them outward at speeds much higher than the CME itself.
In some cases, where the Sun’s magnetic field is in a favorable direction, the protons can reach a large fraction of the speed of light. Electromagnetic radiation from the flare reaches Earth in just over 8 minutes, but the fastest proton storms may arrive just 30 minutes or so later.
High-energy X-rays and ultraviolet rays are absorbed by the glow in our planet’s upper atmosphere, and Earth’s magnetic field greatly deflects solar protons, helping to protect Earth from the most dangerous effects of these solar events. However, solar flares can still have significant effects on Earth.
Individual atoms and gas molecules in Earth’s atmosphere become ionized, or electrically charged, when they absorb radiation from flares. This can interfere with short-wave radio communications, which rely on bouncing signals from charged gases in the ionosphere. Electric currents flowing through ionized gases and within a proton storm can distort the overall structure of the Earth’s magnetic field (although not as much as the CME would later hit).
However, flares in general pose a greater risk to human technology than to the people themselves. X-rays hitting the satellite can ionize its materials, while protons can supply electricity to the outer surfaces of those materials, resulting in short circuits and malfunctions. The energy flowing into the upper atmosphere can also cause the gases there to heat up and expand, increasing drag on satellites and causing their orbits to decay.
