Components of the Solar Atmosphere

The Solar Atmosphere

The solar atmosphere consists of three distinct layers: the Photosphere, the Chromosphere, and the Corona. Below are detailed descriptions of these elements.

Photosphere

The photosphere is the innermost layer of the solar atmosphere and the layer that we can see with the naked eye.
It is sometimes referred to as the Sun’s “surface”, although the Sun being a ball of gas, doesn’t have a solid surface.
The photosphere comprises mainly hydrogen gas and emits light and heat.
The temperature of the photosphere decreases with height. It averages around 5500°C at the bottom and decreases to about 4000°C at the top.
It’s also the layer where sunspots, short-term phenomena caused by intense magnetic activity, occur. These are areas that appear dark as they are cooler than their surroundings.

Chromosphere

Above the photosphere is the chromosphere, a layer much less bright but hotter than the photosphere.
It’s invisible against the brightness of the photosphere except during total solar eclipses, where it may appear as a reddish ring.
The chromosphere features eruptions called solar prominences or filaments, which are loops of gas following magnetic fields.
In the chromosphere, temperatures rise from about 4000°C near its bottom to about 25000°C near its top. This increase in temperature with height is opposite to what happens in the photosphere.

Corona

The corona is the outermost layer of the solar atmosphere, extending millions of kilometres into space.
It’s visible during total solar eclipses as a halo of plasma surrounding the Sun.
Temperatures in the corona are incredibly high, reaching over a million degrees Celsius. The reason for this is not fully understood but is thought to be related to the Sun’s magnetic field.
The corona also is the launching pad for solar wind, a continuous flow of charged particles that pervades the solar system.

These layers of the solar atmosphere all play key roles in the Sun’s dynamics and overall solar activity. Awareness of the characteristics of each layer aids in the understanding of solar phenomena, such as solar flares and solar wind.