Answer :
Limb darkening is when the edge of the sun appears darker than its center, primarily due to the way light is absorbed differently in the sun's atmosphere. Light from the limb travels through more atmosphere, leading to increased absorption and a darker appearance.
Limb darkening is an optical effect seen in stars like the Sun, where the central part of the stellar disk is brighter compared to its edges or limb. This effect is a consequence of the way light travels through the Sun's atmosphere. There is a notable diminution of light at the solar limb when compared to the center, where the light intensity is about one-third as strong.
The primary cause of limb darkening is the differential absorption of the Sun's rays by its atmosphere. As light travels through the atmosphere, it is absorbed; however, light that emanates from the limb of the sun travels through a greater extent of the solar atmosphere compared to light from the center, leading to more absorption and hence, a darker appearance. This is particularly evident in the blue end of the spectrum.
Empirical models and assumptions about the Sun's atmosphere help us understand this phenomenon better. By assuming a uniform Lambertian radiance from the solar surface and considering the absorbing properties of the Sun's atmosphere, we can correlate the observed limb darkening with theoretical models. Additionally, differences in absorption of various wavelengths contribute to the color differences observed at the limb, with red and yellow rays appearing less affected compared to blue and violet rays.
The edge, called the limb, of the sun is darker than the center of the sun.
Therefore, it is clear that if the limb is the edge of the sun, limb darkening is when the limb is darker, and has a lower level of brightness that the middle of the sun.
Hope this helps, let me know if you need anything else! :)
