Monday 24 June 2024

Wonder-filled Solar System - Part II


Many astonishing phenomena occur in the Sun's corona, such as solar winds, solar flares, solar storms, and sunspots.


Solar Wind

Due to the extreme temperatures, charged particles—protons and electrons—are continuously ejected from the Sun's corona. These particles travel at speeds of about 300 to 800 kilometres per second, spreading throughout the solar system. The high-speed movement of these charged particles significantly impacts the magnetic fields of the planets. On planets with magnetic fields, the interaction with the solar wind creates auroras at the poles. The solar wind also disrupts the normal operations of satellites traveling through space. The intensity of the solar wind is not constant; it varies, sometimes increasing and sometimes decreasing. Despite the consistent temperature of the corona, the variation in solar wind flow remains a mystery. 

Aurora borealis (photo: Amena Islam)


Every eleven years, dark spots appear on the Sun's photosphere. These spots, known as sunspots, can range from 1,000 kilometers to 100,000 kilometers in size and can last from an hour to several weeks. Galileo first observed sunspots in 1513, but their magnetic nature was not discovered until 1908 by American astronomer George Hale.

Sunspots (photo – NASA)

Sunspots are akin to sores on the Sun's surface. The Sun revolves around the centre of the Milky Way at a speed of 240 kilometres per second, and it also rotates on its axis at an average speed of about 2 kilometres per second. This movement generates a powerful magnetic field within its gas. Every eleven years, the direction of this magnetic field changes, though the reason for this cycle is still unknown. When the magnetic field changes direction, closed magnetic loops are created in certain areas, trapping some gas on the Sun's surface. The plasma flow is blocked in these loops, causing the trapped gas to cool slightly compared to the surrounding gas, resulting in darker areas that appear as sunspots. The number of sunspots can vary greatly from year to year, ranging from less than ten to more than one hundred.

Solar Storms and Solar Flares

The Sun's weather is far from calm. Solar storms occur on the Sun's surface, but unlike storms on Earth, they are caused by the flow of electric and magnetic fields. Massive gas waves rise from the chromosphere to the corona, and these waves are visible when sunspots appear due to the Sun's magnetic field. Each wave can span thousands of kilometres and last for several weeks. Sometimes, large columns of gas shoot out from the chromosphere during solar storms. Occasionally, a sudden burst of energy erupts like a fiery flood. If harnessed, the energy from a single eruption could power Earth for a million years.

Solar flare (Photo: NASA)

Solar storms are triggered by sunspots. When sunspots occur, magnetic loops form, and if several loops merge and grow, the gas trapped within them can burst out violently, similar to a short circuit. These solar flares can extend hundreds of thousands of kilometres and can cause disruptions in Earth's networks. The influx of charged particles into Earth's atmosphere also affects satellites and spacecraft.

Solar storm (Photo: NASA)

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