In a previous post I quoted a verse from Stesichorus which started
ἀέλιος δ᾽ Ὑπεριονίδας δέπας ἐσκατέβαινε
And then the Sun, great Hyperion’s offspring,
Embarked in his golden cup.
Stesichorus Ath. 11.38
Now it struck me at the time that a cup was rather an odd means of transportation especially for quite a large god. However Heraclitus seems to give the answer. If the sun and other heavenly bodies were bowls – imagine a hollow ball cut in half – then you had an explanation for eclipses and the phases of the moon. This is from Diogenes Laertius’ life of Heraclitus (9.1)
τὸ δὲ περιέχον ὁποῖόν ἐστιν οὐ δηλοῖ: εἶναι μέντοι ἐν αὐτῷ σκάφας ἐπεστραμμένας κατὰ κοῖλον πρὸς ἡμᾶς, ἐν αἷς ἀθροιζομένας τὰς λαμπρὰς ἀναθυμιάσεις ἀποτελεῖν φλόγας, ἃς εἶναι τὰ ἄστρα. λαμπροτάτην δὲ εἶναι τὴν τοῦ ἡλίου φλόγα καὶ θερμοτάτην. τὰ μὲν γὰρ ἄλλα ἄστρα πλεῖον ἀπέχειν ἀπὸ γῆς καὶ διὰ τοῦτο ἧττον λάμπειν καὶ θάλπειν, τὴν δὲ σελήνην προσγειοτέραν οὖσαν μὴ διὰ τοῦ καθαροῦ φέρεσθαι τόπου. τὸν μέντοι ἥλιον ἐν διαυγεῖ καὶ ἀμιγεῖ κινεῖσθαι καὶ σύμμετρον ἀφ᾽ ἡμῶν ἔχειν διάστημα: τοιγάρτοι μᾶλλον θερμαίνειν τε καὶ φωτίζειν. ἐκλείπειν τε ἥλιον καὶ σελήνην, ἄνω στρεφομένων τῶν σκαφῶν: τούς τε κατὰ μῆνα τῆς σελήνης σχηματισμοὺς γίνεσθαι στρεφομένης ἐν αὐτῇ κατὰ μικρὸν τῆς σκάφης.
He doesn’t make clear what surrounds us. He does say that there are bowls with their hollow side turned towards us into which the bright vapours (which rise from the sea) gather and produce flames which he says are the stars and the brightest and warmest flame is the sun. The other stars are further away from the earth and this is why they are less bright and warm and the moon which is closer moves through an area that is not clean. But the sun moves through a bright and pure area at a suitable distance so gives us more warmth and light. You get eclipses of the sun and the moon when the bowls are turned upwards and the phases of the moon when the bowl turns round little by little.