Asteroid 3200 Phaethon, a strange galaxy, is stranger than astronomers thought, NASA researchers said Tuesday.
The asteroid behaved like a comet and astronomers thought its tail was made of dust, but a new study published in The Planetary Science Journal found that the tail was actually made of sodium gas.
Qicheng Zang, a California Institute of Technology PhD student who is the study’s lead author, used the Solar and Heliospheric Observatory spacecraft to examine Phaethon and its tail. Most asteroids, which are made of rock, do not typically form tails as they approach the sun, according to NASA. Comets, which are made of rock and ice, usually form tails.
Based on the Phaethon study, Zhang and other scientists wonder if some comets might not be comets at all.
“Many of the other ‘comets’ in the sunskirting may not even be ‘comets’ in the usual, icy body sense, but may instead be rocky asteroids like Phaethon that have been heated by the sun,” Zhang said in a post of NASA.
Phaethon is also the source of annual Geminid meteor shower, although comets cause most meteor showers. When astronomers thought that Phaethon’s tail was made of dust, it made sense because the burning pieces of the debris trail produced meteor showers. Now experts are left scrambling to answer how Phaethon, with its sodium gas tail, provides the material for the Geminid meteor shower every December.
There may have been a disruptive event several thousand years ago that caused Phaethon to eject the material that made up the Geminid debris stream, Zhang’s team said.
Researchers may get more answers in the next decade. The Japan Aerospace Exploration Agency’s upcoming mission called DESTINY+ is expected to fly by Phaethon, imaging its rocky surface and studying any dust that may exist around the asteroid.
Phaethon It also caught NASA’s attention in 2017 when it was so close to Earth that it was classified as “potentially hazardous” by the International Astronomical Union’s Minor Planet Center.
