A new study using two NASA solar observatories has revealed that the tail of asteroid 3200 Phaethon is not made of dust, but is actually made of sodium gas. Scientists had previously blamed Phaethon’s comet-like behavior on dust escaping from the asteroid as it’s scorched by the Sun. However, observations from NASA’s Parker Solar Probe showed that the trail contained far more material than Phaethon could possibly shed during its close approaches to the Sun. An earlier study suggested that the Sun’s intense heat during Phaethon’s close solar approaches could vaporize sodium within the asteroid and drive comet-like activity. The recent study confirms this theory, indicating that Phaethon’s tail is made of sodium, not dust.
