Since the sun is in the middle of the universe, the distance between the sun and the edge of the universe is calculated to be twenty-five koti yojanas - two billion miles

Expressions researched:
"since the sun is in the middle of the universe, the distance between the sun and the edge of the universe is calculated to be twenty-five koti yojanas"

SB Canto 5

The word koṭi means ten million, and a yojana is eight miles. The diameter of the universe is fifty koṭi yojanas (four billion miles). Therefore, since the sun is in the middle of the universe, the distance between the sun and the edge of the universe is calculated to be twenty-five koṭi yojanas (two billion miles).

SB 5.20.43, Translation and Purport:

The sun is situated (vertically) in the middle of the universe, in the area between Bhūrloka and Bhuvarloka, which is called antarikṣa, outer space. The distance between the sun and the circumference of the universe is twenty-five koṭi yojanas (two billion miles).

The word koṭi means ten million, and a yojana is eight miles. The diameter of the universe is fifty koṭi yojanas (four billion miles). Therefore, since the sun is in the middle of the universe, the distance between the sun and the edge of the universe is calculated to be twenty-five koṭi yojanas (two billion miles).