§1.7#17 ἐπεὶ δὲ περὶ τῶν ἀφανῶν τῇ αἰσθήσει νομίζομεν ἱκανῶς ἀποδεδεῖχθαι κατὰ τὸν λόγον, ἐὰν εἰς τὸ δυνατὸν ἀναγάγωμεν, ἔκ τε τῶν νῦν φαινομένων ὑπολάβοι τις ἂν ὧδε περὶ τούτων μάλιστα συμβαίνειν·
7. Since we consider that we have given a sufficient rational proof concerning things invisible to sense, if we reduce them to what is possible, one might suppose, from the phenomena now visible, that the case stands most of all as follows concerning these matters.
ὑπόκειται γὰρ ἡμῖν τοῦ κόσμου τοῦ περὶ τὴν γῆν, ὅσον ὑπὸ τὴν ἐγκύκλιὸν ἐστιν φοράν, εἶναι τὸ πρῶτον μέρος ἀναθυμίασιν ξηρὰν καὶ θερμήν·
For it is assumed by us that, of the world around the earth, as much of it as lies beneath the circular motion, the first part is a dry and hot exhalation.
αὕτη δὲ αὐτή τε καὶ τοῦ συνεχοῦς ὑπʼ αὐτὴν ἀέρος ἐπὶ πολὺ συμπεριάγεται περὶ τὴν γῆν ὑπὸ τῆς φορᾶς καὶ τῆς κινήπροσπεφιλονείκεικεν] σεως τῆς κύκλῳ·
And this exhalation itself, as well as much of the continuous air beneath it, is carried round the earth by the circular motion and movement.
φερομένη δὲ καὶ κινουμένη τοῦτον τὸν τρόπον, ᾖ ἄν τύχῃ εὔκρατος οὖσα, πολλάκις ἐκπυροῦται· διὸ φαμεν γίγνεσθαι καὶ τὰς τῶν σποράδων ἀστέρων διαδρομάς.
And being carried and moved in this manner, wherever it happens to be of a suitable temperament, it often ignites; and for this reason we say that the shooting of scattered stars also takes place.
ὅταν οὖν εἰς τὴν τοιαύτην πύκνωσιν ἐμπέσῃ διὰ τὴν ἄνωθεν κίνησιν ἀρχὴ πυρώδης, μήτε οὕτω πολλὴ λίαν ὥστε ταχὺ καὶ ἐπὶ πολὺ ἐκκαίειν, μήθʼ οὕτως ἀσθενὴς ὥστε ἀποσβεσθῆναι ταχὺ, ἀλλὰ πλείων καὶ ἐπὶ πολύ, ἅμα δὲ κάτωθεν συμπίπτῃ ἀναβαίνειν εὔκρατον ἀναθυμίασιν, ἀστὴρ τοῦτο γίγνεται κομήτης, ὅπως ἂν τὸ ἀναθυμιώμενον τύχῃ ἐσχημαατισμένον·
Whenever, therefore, an inflammatory source falls into such a condensation because of the motion from above, and it is neither so very great as to burn up quickly and extensively, nor so weak as to be extinguished quickly, but is rather substantial and lasts for a long time, and at the same time a suitably tempered exhalation happens to ascend from below, this becomes a comet, according as the exhaling matter happens to be shaped.
ἐὰν μὲν γὰρ πάντη ὁμοίως, κομήτης, ἐὰν δʼ ἐπὶ μῆκος, καλεῖται πωγωνίας.
For if it is shaped equally in all directions, it is called a comet; but if it is elongated, it is called a bearded star.
ὥσπερ δὲ ἡ τοιαύτη φορὰ ἀστέρος φορὰ δοκεῖ εἶναι, οὕτως καὶ ἡ μονὴ ἡ ὁμοία ἀστέρος μονὴ δοκεῖ εἶναι·
And just as such a movement seems to be the movement of a star, so also a similar remaining seems to be the remaining of a star.
παραπλήσιον γὰρ τὸ γιγνόμενον οἷον εἴ τις εἰς ἀχύρων θημῶνα καὶ πλῆθος ὤσειε δαλὸν ἢ πυρὸς ἀρχὴν ἐμβάλοι μικράν· φαίνεται γὰρ ὁμοία καὶ ἡ τῶν ἀστέρων διαδρομὴ τούτῳ· ταχὺ γὰρ διὰ τὴν εὐφυίαν τοῦ ὑπεκκαύματος διαδίδωσιν ἐπὶ μῆκος.
For what happens is very like as if one were to thrust a brand into a heap and quantity of chaff, or throw a small spark of fire into it; for the shooting of the stars also appears similar to this, for it quickly spreads along a length owing to the suitability of the fuel.
εἰ δὴ τοῦτο μείνειε καὶ μὴ καταμαρανθείη διελθὸν, ᾗ μάλιστα ἐπύκνωσε τὸ ὑπέκκαυμα, γένοιτʼ ἂν ἀρχὴ τῆς φορᾶς ἡ τελευτὴ τῆς διαδρομῆς.
If indeed this should remain and not be extinguished after passing through, where the fuel was most dense, the end of the shooting would become the beginning of its movement.
τοιοῦτον ὁ κομήτης ἐστὶν ἀστήρ, ὥσπερ διαδρομμἡ ἀστέρος, ἔχων ἐν ἑαυτῷ πέρας καὶ ἀρχήν.
Such a star is a comet, being like a shooting of a star, having in itself its own end and beginning.
ὅταν μὲν οὖν ἐν αὐτῷ τῷ κάτω τόπῳ ἡ ἀρχὴ τῆς συστάσεως ᾖ, καθʼ ἐαυ τὸν φαίνεται κομήτης·
When, therefore, the beginning of the compilation is in the lower region itself, it appears as a comet by itself.
ὅταν δʼ ὑπὸ τῶν ἄστρων τινός, ἢ τῶν ἀπλανῶν ἢ τῶν πλανήτων, ὑπὸ τῆς κινήσεως συνιστῆται ἡ ἀναθυμίασις, τότε κομήτης γίγνεται τούτων τις·
But when the exhalation is compiled by the motion of one of the stars, whether of the fixed or of the planets, then one of these becomes a comet.
οὐ γὰρ πρὸς αὐτοῖς ἡ κόμη γίγνεται τοῖς ἄστροις, ἀλλʼ ὥσπερ αἱ ἅλῳ περὶ τὸν ἥλιον φαίνονται καὶ τὴν σελήνην παρακολουθοῦσαι, καίπερ μεθισταμένων, ὅταν οὕτως ᾖ πεπυκνωμένος ὁ ἀὴρ ὥστε τοῦτο γίγνεσθαι τὸ πάθος ὑπὸ τὴν τοῦ ἡλίου πορείαν, οὕτω καὶ ἡ κόμη τοῖς ἄστροις οἶον ἄλως ἐστίν·
For the tail does not arise close to the stars themselves, but just as halos appear around the sun and the moon, following them although they move, when the air is so condensed that this affection occurs under the path of the sun, so also the tail is like a halo for the stars.
πλὴν ἡ μὲν γίγνεται διʼ ἀνάκλασιν τοιαύτη τὴν
Except that the halo arises through reflection of such a kind...