"Thus to the earth they gave the name P'RTHOVI, "the wide expanse;" the blue and star-bespangled heavens they called VARUNA, "the vault;" and beneath it in the region of the clouds they enthroned the light DYAUS, i.e. "the luminous air."
followed by this image
Upon researching further, I only found that the heavens are called 'Dyaus' and the mid-region is called 'Antariksh'. So how accurate is this image and what do we know about the three worlds in Vedic era?