The diameter of the Moon is 400 times smaller than the diameter of the Sun, but it is also 400 times closer to us.
So it covers the Sun nearly perfectly and only the corona can be seen around it.
A happy coincidence?

The Center for Deep Space Communications, Crimea.
The RT-70 radio telescope is 86m in height and 70m in diameter, operating in deep space programs.

Our retinas have two types of photoreceptor cells: rods (sensitive enough for night time, but black&white only) and cones (color vision possible at a day time).
So while the night sky appears black&white to the naked eye, it's indeed colorful.