The Greek original: πᾶσιν δὲ τούτοις τὰ μὲν κοινῇ συμπίπτει λέγειν ἀδύνατα͵ τὰ δὲ χωρίς. πρῶτον μὲν οὖν τοῖς λέγουσιν ὅτι τῶν πλανωμένων ἐστὶν εἷς ἀστέρων ὁ κομήτης· οἱ γὰρ πλανώμενοι πάντες ἐν τῷ κύκλῳ ὑπολείπονται τῷ τῶν ζῳδίων͵ κομῆται δὲ πολλοὶ ἑωραμένοι εἰσὶν ἔξω τοῦ κύκλου. εἶτα καὶ πλείους ἑνὸς ἅμα γεγένηνται πολλάκις. πρὸς δὲ τούτοις͵ εἰ διὰ τὴν ἀνάκλασιν τὴν κόμην ἴσχουσι͵ καθάπερ φησὶν Αἰσχύλος καὶ Ἱπποκράτης͵ ἔδει ποτὲ φαίνεσθαι καὶ ἄνευ κόμης τὸν ἀστέρα τοῦτον͵ ἐπειδήπερ ὑπολείπεται μὲν καὶ εἰς ἄλλους τόπους͵ τὴν δὲ κόμην ἴσχει οὐ πανταχοῦ· νῦν δ΄ οὐδεὶς ὦπται παρὰ τοὺς πέντε ἀστέρας· οὗτοι δὲ πολλάκις ἅμα πάντες μετέωροι φαίνονται ὑπὲρ τοῦ ὁρίζοντος. καὶ φανερῶν δὲ ὄντων αὐτῶν ἁπάντων καὶ μὴ φαινομένων πάντων͵ ἀλλ΄ ἐνίων ὄντων πρὸς τῷ ἡλίῳ͵ οὐδὲν ἧττον κομῆται φαίνονται γιγνόμενοι πολλάκις.
Translated in English from http://www.ellopos.net/elpenor/greek-texts/ancient-greece/aristotle/meteorology.asp?pg=11 : These views involve impossibilities, some of which are common to all of them, while others are peculiar to some only. This is the case, first, with those who say that the comet is one of the planets. For all the planets appear in the circle of the zodiac, whereas many comets have been seen outside that circle. Again more comets than one have often appeared simultaneously. Besides, if their tail is due to reflection, as Aeschylus and Hippocrates say, this planet ought sometimes to be visible without a tail since, as they it does not possess a tail in every place in which it appears. But, as a matter of fact, no planet has been observed besides the five. And all of them are often visible above the horizon together at the same time. Further, comets are often found to appear, as well when all the planets are visible as when some are not, but are obscured by the neighbourhood of the sun.