भगोल · खगोल · भूगोल
Sanskrit astronomy has two words for the sphere over your head, and modern Indian schooling kept only one of them. खगोल khagola gave Hindi and Marathi their word for astronomy, खगोलशास्त्र; भगोल bhagola gave them nothing, and survives mainly in dictionaries. So an atlas called भगोल looks, at first glance, like it reached for the astronomy word and missed — or, to most readers, like a misspelling of भूगोल, the geography they did sit exams in.
It is neither. The two words name two different spheres, and the difference between them is the one thing a planetarium has to get right: which of them moves. Every quote below is a slice from Jñānakośa, the research database behind this atlas; each links to the e-text it was sliced from. Translations are literal renderings. Display markup of the e-texts is removed here.
गोल · the shared noun
गोल is not a technical term at all. It is a ball — the round thing — and the tradition named its spherical astronomy after it: Āryabhaṭa's fourth chapter is the Golapāda, the Sūrya-siddhānta's twelfth is the Bhūgolādhyāya, Bhāskara's book of spherics is simply the Golādhyāya. What is technical is the syllable in front. Āryabhaṭa puts three subjects in one compound as his spherics opens, and gives each of them a गोल of its own:
भूग्रहभानाम् — of the earth, of the planets, of the stars. That third member is the one that loses a modern reader: on its own, भ bha is a star, an asterism. It is the same bha that makes भगण bhagaṇa, one full revolution through the stars, and भचक्र bhacakra, the star-wheel. The Sūrya-siddhānta's pupil uses it in the first breath of his questions:
ख kha, meanwhile, is space — the emptiness itself. Three prefixes, one noun, three entirely different objects:
ख · the space you stand in the middle of
Here is kha doing its work, in the verse usually quoted for Āryabhaṭa's cosmology. Read it for the architecture rather than the astronomy: a round cage of stars on the outside, the orbits wrapped inside that, space in the middle, and the earth standing at the centre of the space.
The khagola is that space taken as a sphere. For anyone standing on the earth in the middle of it, it is the frame: the horizon, the meridian, the prime vertical, the circles fixed to where you are rather than to anything in the sky. The Purāṇas already treat it as a subject in its own right, listed beside the earth's sphere and the wheel of lights as three things a teacher covers separately:
See: the same passage read as an instrument, in essay four
भगोल · परिवर्तते
The bhagola is the other cage — the stars themselves, set in a sphere. Āryabhaṭa's first remark about it is an observer's remark rather than a cosmologist's: you never get all of it, and you get slightly less than half, because you stand on the earth's surface and not at its centre.
Now the asymmetry that settles the question. Search the siddhāntas for what revolves, and the subject of the verb is never the khagola. It is this one. The Sūrya-siddhānta, deep in its account of the polar day, watches the direction of the turning reverse as you cross to the other hemisphere:
Āryabhaṭa makes the same observation with the same word, and gives the two poles their opposite views of it — gods on Meru in the north, the dead at Baḍavāmukha in the south, watching one sphere run in two directions:
भूभगोल · one cage inside another
So the pair divides cleanly by what it does. One sphere is the frame you observe from, and it does not move; the other carries the stars and turns inside it.
In fairness, the crisp technical pairing of the two names belongs to the later spherics writers — Bhāskara's Golādhyāya works it out most fully, and that text is not in the corpus behind this atlas. What the corpus does carry is the asymmetry itself, and an instrument built on it.
The Sūrya-siddhānta's thirteenth chapter tells you to build the thing. Make an earth-globe of wood; run a rod through it and out both sides at Meru; hang the circles around it. And the name it gives the finished instrument welds both words together — भूभगोल, the earth-and-star sphere:
See: the rest of chapter thirteen, in essay four
भूगोल · a note on the third
The third gola is the one every Indian reader actually met, and it is not about the sky at all. The Sūrya-siddhānta's twelfth chapter is titled the Bhūgolādhyāya, and it opens with Maya putting his questions to an emanation of the sun — every one of them about the ground:
That chapter went on to become a school subject: भूगोल is the ordinary modern word for geography in Hindi, Marathi, Gujarati and Bengali — the textbook, the map on the classroom wall, nothing in it pointing upward any more. It is also, for the same reason, the only गोल most readers have ever seen in print, which is why भगोल reads as a spelling mistake. It is not a mistake, and it is not the same word: भगोल turns up sixty verses further into that very chapter, at the point where the subject stops being the ground and starts being the sky.
Of the three spheres, two found modern work. भूगोल took geography. खगोल took astronomy, and took it fairly: खगोलशास्त्र is a good name for the discipline, because the discipline really is about the frame — coordinates, circles, the machinery for saying where. भगोल got nothing, and it is the only one of the three that names what is actually up there: the stars, in a sphere, turning.
Which is what this atlas is a catalogue of. Not the frame but its contents — 975 names in 57 languages of South Asia for the objects on that turning sphere, each one cited to the source that recorded it. The app (Android, iPhone) draws the khagola too: the Gol Yantra layer is the armillary's own reference circles, the meridian and the prime vertical and the six o'clock circle, held still while everything else goes past them. But what it is about is the other sphere. Every quotation above carries its full citation, edition and revision-pinned source link in Jñānakośa.
Sanskrit texts on the sky and the sciences around it, one thread per essay — readable in any order.