In Plato's work, Phaethon is brought up shortly. "There is a story, which even you have preserved, that once upon a time Paethon, the son of Helios, having yoked the steeds in his father's chariot, because he was not able to drive them in the path of his father, burnt up all that was upon the earth, and was himself destroyed by a thunderbolt." 

This episode explores Phaethon in depth and explores the small amount of information about him.  I thought I would go over Phaethon and what the audience of Plato would have known. Plato talks about it briefly but enough that I think you should know the story. If the words comet, meteor, or asteroid were not available, How would you describe a ball of fire coming down from the sky?

sources:

https://en.wikipedia.org/wiki/Merops_(mythology)

https://en.wikipedia.org/wiki/Clymene_(mother_of_Phaethon)

https://www.theoi.com/Titan/Phaethon.html

https://www.theoi.com/Nymphe/NymphaiHeliades.html

https://www.theoi.com/Nymphe/NympheKlymene.html

https://www.theoi.com/Potamos/PotamosEridanos.html

https://www.evolving-science.com/information-communication/meteor-explosion-could-have-taken-out-entire-bronze-age-civilization-new-research-reveals-00855