The first mass structure Singularity according to the First chapter of Genesis of The Biblical record of Creation was the micro mass structure of the particle of Light.
Light is basically an invisible particle and unless a particle of light flux enter our eye we have no information about our surroundings.
The Sun is basically a nuclear mass structure forming a nuclear fusion process between a Carbon to helium and Hydrogen cycle ,whose mass loss radiation manifests itself in term of protons ,alpha a beta and gamma radiation and mixed with it light radiation.
The atomic fusion reaction of the sun radiation produces two thirds of the total radiation in the form of light.
Logically it makes sense to believe that light particle is the basic structure all all the atoms inherent to the Sun.
Hence, the indication of the first mass creation to be light does make both Scientific and Biblical sense.As it was out lined in Genesis of the Holy Bible.
Nevertheless .The nature of light still remains a puzzle with very little explication by main stream Physics(the Standard model).Not much is explicated in this model about the basics of Creation when our Creators moved Upon the Waters.
The Biblical meaning in the first verse of Genesis about the creation of the Heavens is the Hebrew Word "Shamayin. "
Sha mean High and Mayin means waters. Water is another word for fluid. We basically live in a fluid just like a fish lives in water.
Light only comes out of atoms. If that is true than atoms are made of light just like the whole volume of the Sun is made of light