A mysterious asteroid “Phaethon” surprises experts again

The asteroid “Phaethon” behaves like a comet and unleashes a shower of shooting stars. Now a new study shows that everything is different than previously thought.

PASADENA – The asteroid “Phaethon” is a strange celestial body: as it approaches the sun, it behaves like a comet and develops a tail. Because of its orbit, Phaethon is believed to be the parent of the annual Geminid stars. Until now, research has assumed that the tail is composed of dust particles, as in the case of comets. If these dust particles remain in space and the Earth moves through the dust path, a stream of shooting stars is created.

But now, a research group led by PhD student Qicheng Zhang of Caltech has found something that turns those assumptions on their head. “Our analysis shows that the comet-like activity of Phaethon cannot be explained by any kind of dust,” Zhang points out in one. communication US space agency NASA. Instead of dust, the tail of the asteroid “Phaethon” appears to be made of sodium. Research work has a research team in the specialized magazine Planetary Science Journal published.

Asteroid ‘Phaethon’ Behaving Like a Comet – Research is Perplexing

The difference between asteroids and comets is their composition: asteroids are usually made of rock and do not form a tail as they approach the sun. On the other hand, comets consist of loose pieces of rock held together by ice. When a comet approaches the Sun, part of the ice becomes gaseous – a tail is formed, in which dust and small pieces of rock from the comet can also be found.

When the asteroid Phaethon was discovered in 1983, it was quickly thought to be the source of Gemini, as its trajectory matched the annual meteor shower. Years later, NASA’s STEREO solar telescope detected a short tail in “Phaethon”—and it seemed clear: Dust from the tail was responsible for falling stars. In 2018, the Parker Solar Probe revealed that a trail of dust in space contained far more material than Phaethon was able to lose during its approach to the Sun.

What is behind the tail of the asteroid “Phaethon”?

That’s why Zhang’s research team asked itself: Is it possible that something other than dust is behind the behavior of the asteroid’s strange tail? Comets often glow with sodium emissions when they are very close to the Sun. So, we suspected that sodium might also play a major role in lightening the Phaethon, Zhang said. Using the NASA/ESA SOHO spacecraft, his team studied the asteroid’s tail as it approached the sun again in 2022.

The space telescope is equipped with color filters that can detect sodium and dust. And here it is: In current and older SOHO images, the researchers found that the asteroid’s tail was bright and visible in the sodium filter — by contrast, the tail did not appear in the dust filter. The research team also found that the tail became bright when Phaethon flew away from the sun – just as the researchers would expect for a sodium tail.

Phaethon: Dean’s asteroid forms a tail of heat from the sun

“We have a really cool result that turns 14 years of thinking into something well-researched,” said Carl Battams, a Naval Research Laboratory team member, adding: “We did this using data from two solar physics spacecraft — SOHO and STEREO — that were never intended to be studied. phenomena like this.”

After this startling discovery, Zhang and his team are considering whether some of the comets discovered by the SOHO probe might not be comets at all. “Many of these other sun-orbiting ‘comets’ may not be ‘comets’ in the usual sense either, but rather rocky asteroids like ‘Phaethon’ that are heated by the sun,” Zhang imagines.

But how does the research group explain the fact that the asteroid Phaethon, which appears to have no dust tail, causes the Geminid meteor shower every December? One theory the team came up with is that something must have happened thousands of years ago that caused the asteroid to lose billions of tons of material. However, what exactly could have led to this is not clear. It looks like the asteroid Phaethon will continue to be a very obscure celestial body, which is always good for a surprise. (unpaid bill)