Astronomers observing the strange "rock comet" hybrid Phaethon as it passed the sun have found a surprise that could upend 14 years of thinking about the weird asteroid.
The asteroid Phaethon, which gives us the Geminid meteor shower every year and was discovered in 1983, has a strange brightening from what appears to be a tail of sodium atoms, and not dust as previously thought, the researchers found.
