Page:Illustrated Astronomy.pdf/32

 Finally, another feature of this layer is the darkening towards the edges, also known as limb darkening, where the Sun’s center appears brighter that the edges.

Why does this happen? When we look at the center of the solar circle, we can see more in-depth, and the light comes straight to us, crossing fewer layers of its atmosphere. On the contrary, if we look at the edges and we want to observe the same depth as if we look at the center, the light would have to go through more layers of the solar atmosphere. So, by observing the edges of the Sun, we can see colder, outer layers, that’s why it looks slightly darker.

Something similar can be observed in the Earth’s atmosphere. The stars in the sky look clearer and static when we look up, whereas if we look to the horizon, they look blurred and blinking because the stars above cross fewer atmospheric layers to approach us.



Nearby the center of the star, a part of the light we observe is in the depths of it, where the temperature is higher, which means more light.

On the contrary, the light we observe near to the edge of a star is produced closer to its surface, where the temperature is colder. 32 • • •