What Is the Photosphere?

The photosphere is the lowest layer of the sun's atmosphere, that is, the surface of the sun generally observed by white light, and has a thickness of about 500 kilometers. The amount of solar energy we receive is basically from light balls. Therefore, the spectrum of the sun is actually the spectrum of a photosphere.

Photosphere

Although the light sphere is bright overall, the brightness of each part is very bright.

Qualitatively know through identification of solar spectral lines

Temperature around the photosphere,

If you do not consider the active area and the grain structure, it is easy to see that the brightness of each part on the photosphere is different: the central area of the sun is the brightest, and the closer to the edge, the darker. This phenomenon is called

In terms of visible light and a part of the ultraviolet and infrared bands, the solar spectrum is basically the spectrum of a photosphere. It is a bright continuous spectrum superimposed with a large number of absorption lines "ie Fraun and Fei lines". Both continuous spectra and absorption lines are formed in the photosphere, but the central part of some strong lines "such as Ha for hydrogen and H for calcium" is formed in the chromosphere. This is because the absorption coefficient there is so large that photosphere radiation cannot be emitted directly. As for the ultraviolet, extreme ultraviolet,

There are many Fraunhofer and Fei lines in the solar spectrum, and there are more than 26,000 in the range of 2935 Angstroms to 13495 Angstroms. They are caused by the absorption or scattering of atoms of various elements. The absorption line contains the temperature, density, pressure, chemical composition,

The average gas density of a photosphere is only a few hundredths of a millionth of that of water. Photosphere gas is so thin that it should be very transparent, but it is not. Although a few centimeters of a thin layer

The photosphere is the circular surface of the sun actually seen. It has a relatively clear circumferential boundary. The surface of the photosphere is gaseous, and its average density is only a few hundredths of a million water. The photosphere is 500 kilometers thick and extremely opaque. The light spheres are densely distributed with extremely unstable speckled spots, which are called "rice grain tissue". Rice grain structure may be caused by the convection of gas under the photosphere. In addition,

Photosphere

There are also super rice grains, whose diameter and life span are much larger. Sunspots and light spots are also distributed in the photosphere, and occasionally white light flare appears. These phenomena have very different brightness, physical state and structure.

The so-called sunspot is a dark area on the photosphere layer. Its temperature is about 4500K, while the rest of the photosphere is about 6000K. It is very dark against the bright light sphere.

A fully developed sunspot consists of a darker nucleus (umbra) and a lighter part (penumbra) surrounding it, shaped like a shallow dish. Sunspots are one of the most visible signs of solar activity. Sunspots are distinguished by a powerful magnetic field, ranging from 500 Gauss of small sunspots to 4000 Gauss of large sunspots. The year with the most sunspots is called the solar maximum year, and the year with the least sunspot is called the solar minimum year. The average activity cycle of sunspots is 11.2 years. There are some brighter areas on the photosphere than the surrounding area, called light spots. It is often accompanied by sunspots.