The sun is very, very big. Each point of the Sun is like a point light source, and about half of the Sun's surface is also visible from Earth during the day, so the light emitted from it reaches us. It is never possible to plot all the light rays emitted by large light sources. But which rays should we draw to make the picture physically correct?

Such a picture of the Sun is not very wrong. After all, light rays are like that, i.e. the light emitted from the Sun in this direction really exists. We have to make ourselves aware of the fact that, physically, only those rays, that is, those directions of light propagation, which are important when located very, very far from the Sun, are left in the image. Therefore: if we look at the Sun from a neighboring star, we can see it in only one direction - light rays coming directly from the Sun.

However, to avoid confusion, we should stick to our general idea - for any large light source, light is emitted in all directions, and only the most important rays at the edges of the beam bundle are drawn. In this way, it is also possible to talk about the fact that the shadows of the Sun are not only full shadows, and also that we see the Sun as a disk, not as a point.

The physicist's Sun is shown in the first picture of this worksheet.