A celestial wonder, the Sun is a massive star that formed from a massive gravitational collapse when space dust and gas from a nebula collided, forming into an orb that is 100 times bigger and weighs over 300,000 times that of planet Earth. Made up of 70 per cent hydrogen and about 28 per cent helium (plus other gases), the Sun is the centre of our solar system and the largest celestial body anywhere near us.
“The surface of the Sun is a dense layer of plasma at a temperature of 5,800 degrees kelvin that is continually in motion through the action of convective motions driven by heating from below,” says David Alexander, a professor of physics and astronomy at Rice University. “These convective motions show up as a distribution of what are called granulation cells about 1,000km across and which appear across the whole solar surface.”
Essentially, this constant motion of high-temperature causes a nuclear reaction. In the core of the Sun, hydrogen turns into helium and causes a fusion – which moves to the surface of the Sun, escaping into space as electromagnetic radiation, a blinding light, and incredible levels of solar heat. In fact, the core of the Sun is actually hotter than the surface, but when the fusion escapes from the surface, the temperature rises to over 1- 2 million degrees. Alexander explained that astronomers do not fully understand why the Sun’s atmosphere is so hot, but think it has something to do with a magnetic field.
Find out more about how the Sun creates heat and light energy by checking out our video below…
What is a solar flare?
A solar flare is like a massive explosion, just one that happens to be several million degrees in temperature. “A solar flare is a rapid release of energy in the solar atmosphere (mostly the chromosphere and corona) resulting in localised heating of plasma to tens of millions of degrees, acceleration of electrons and protons to high energies, some to near the speed of light, and expulsion of material into space,” says Alexander. “These electromagnetic disturbances here on Earth pose potential dangers for Earth-orbiting satellites, space- walking astronauts, crews on high-altitude spacecraft, and power grids on Earth.”
What is a sunspot?
Far below the surface of the Sun, near the core, a strong magnetic field – which is the force created by the Sun’s high core temperature and nuclear fusion – emits a sunspot, which looks like a black dot on the Sun because it is about 1,000 degrees cooler than the surface temperature. Interestingly, a sunspot also causes the magnetic field required for solar flares and a CME. “A CME (coronal mass ejection) is an additional phenomenon which is separate but often accompanies the largest flares,” says Alexander, explaining how plasma from a CME ejects from the Sun at over 1 million miles per hour.
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