Shiva Purana

siva.sh/siva-purana/uma-samhita/19/1

सनत्कुमार उवाच ।। रविचन्द्रमसोर्यावन्मयूखा भासयंति हि।। तावत्प्रमाणा पृथिवी भूलोकस्स तु गीयते ।। १।।

sanskrit

Sanatkumāra said:— The extent to which the rays of the sun and the moon shine and illuminate is the size of the earth. It is called Bhūloka.

english translation

sanatkumAra uvAca || ravicandramasoryAvanmayUkhA bhAsayaMti hi|| tAvatpramANA pRthivI bhUlokassa tu gIyate || 1||

hk transliteration by Sanscript