In Hindu scriptures, Rahu is referred as Chhayaa (shadow). It is correct because IR, which Pundit commander Santosh Kumar Sharma refers as Rahu, is invisible to naked eyes. IR is in between Red and Micro woven frequency range and hence has the element of heat. Heat is required for origination, growth, and sustenance of all organisms and living beings. That is why, Rahu is such an essential form of energy.