Ages before Newton,the ancient Indian Vedic knowledge had revealed that the sunlight consists of seven colours.
Sapta tvaa harito rathe vahanti deva surya shociksesham vicaksana
ava divastaarayanti sapta suryasya rasmyah
(Rigveda 1.50.9)
(Atharvaveda 17-10-17-1)
Sun's seven coloured rays are making a day.
Does that means sun has only seven rays? No, sun emits millions of rays. But each ray of light has seven colours embeded in it. The Vedic terminology often refers to word "saptha ashva ruda". It actually means seven coloured white sunrays. The Vedic meaning of word "ashva" also means "light rays".
The Taittriya aranyakam says "eko-ashva vahati sapta namah".
(Rigveda 1-164-2)
It means sun Light is one(white) but called as seven,figuratively the above sloka can be expressed as sun being carried by one horse called with seven names.
Interestingly in Chandogya Upahishad there is a sloka(8-6-1),it says that sun's ray has three colours;they are blue,yellow and red. Infact lhis is also true in the sense that three colours are the.basic colours,which become other colours.
