The ionosphere is a layer of the Earth’s atmosphere ionized by the solar wind. It allows for AM radio waves to travel farther, but can cause blackouts during solar flares. Scientists study it through auroras. Its discovery began with James Clerk Maxwell’s theory in 1864 and was named the ionosphere in 1926.
The ionosphere is a layer of the Earth’s atmosphere that is ionized by the solar wind. The solar wind exists because the corona, which is the outermost layer of the solar atmosphere, is extremely hot and large. Because it is so large, a constant stream of hydrogen and helium ions, called the solar wind or plasma, is able to leave the sun’s gravity. The solar wind moves away from the sun and towards the Earth, where it affects the magnetosphere, ionosphere and the Earth’s magnetic field.
The ionosphere contains plasma and is made up of three layers. The lowest is called the D region, reaching from 47-59 miles (75-95 km) above the Earth’s surface, and doesn’t contain many ions. The next layer is called the E region, reaching from 59-93 miles (95-150 km) and containing a slightly higher ion concentration. Region F contains the highest ion density and extends from 93-621 miles above the surface.
This layer of the atmosphere is important to everyday life because it allows us to send AM frequency radio waves much farther than we would be able to without it. However, a fairly well-known side effect is that when the sun has released a particularly strong solar flare, the AM radio may experience a blackout. However, the ionosphere does not affect FM frequency radio waves because they have higher frequencies. Therefore, FM frequency radio waves cannot reach AM frequency waves.
Scientists study the ionosphere largely by observing auroras, which are natural displays of brilliant color in the sky near the north and south poles. Auroras occur because, at the poles, there is no magnetosphere. Since there is no magnetosphere, ions can enter the ionosphere and excite the plasma it contains, which then releases the energy as visible light. The frequency and intensity of the auroras are influenced by the occurrence of solar flares and the intensity of the solar wind.
The ionosphere was gradually discovered through a series of scientific discoveries and observations beginning in 1864, when James Clerk Maxwell put forward a theory of how electromagnetic waves are created. In 1901, Marconi used that theory to transmit radio waves, a form of electromagnetic waves, across the Atlantic Ocean. He was able to do this because he knew that since he couldn’t see the receiving station, the radio waves must be bouncing off part of the atmosphere, allowing them to travel farther than intended. In 1902, Oliver Heaviside and Arthur Kennelly learned of Marconi’s findings on radio propagation and concluded that the atmosphere had a reflective layer. However, the layer wasn’t actually called an ionosphere until 1926, when physicist Robert Watson-Watt wrote a paper about it.
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