In hinduism people worship sun as "Lord Surya". According to rig veda,
"Seven horses draw the
chariot of Surya". Rig Veda 5. 45. 9
These seven horses are the seven colors compromising light. These seven colors
become visible in a rainbow or when light passes through a prism.Modern physics confirmed that the sun's rays
travel in a curved way, but not in a straight line. Our ancestors told that the
sun's chariot was drawn by seven horses tied by snakes. As the movements of the
snakes are crooked and curved, so also the sun's ray.
The phenomenon is
described in a metaphysical poetic line bhujagana mita sapta turaga. The chapter
on light says that there are seven colors in the white ray of the sun.
Artharveda says that there are seven types of sun's rays, sapta surayasya
This theory is also related with another one concept in hinduism. These seven colours in the sun ray also represents the seven important chakras of the body namely
Crown of head
Centre of eyebrows
Right of the physical heart
Its really amazing how our ancestors related each and every part of our religion with todays modern science.