BackNasa resolves mystery of asteroid’s comet-like tail
Asteroid 3200 Phaethon acts just like a comet. It brightens and forms a tail when it comes near the Sun
PremiumAsteroid Phaethon, which gives us the Geminid meteor shower every year and was discovered in 1983, has a strange brightening and froms a tail of sodium atoms when it nears the Sun, not of dust as previously thought, the researchers have found.
Astronomers observing the asteroid 3200 Phaethon as it passed the Sun have found a surprise that could change the thinking about this weird asteroid.
Asteroids are mostly rocky leftovers from the early formation of our solar system and do not usually form tails when they approach the Sun. Contrarily, comets are made up of ice and rock, and they do form tails as the Sun vaporizes their ice, blasting off material from their surfaces and leaves a trail along their orbits.
However, this weird asteroid 3200 Phaethon acts just like a comet. It brightens and forms a tail when it comes near the Sun.
So far, scientists have blamed this behaviour due to the escape of dust from the asteroid 3200 Phaethon while coming closer to the Sun. But the latest study using two NASA solar observatories has reveals that Phaethon’s tail is not made of dust but is primarily composed of sodium gas.
The latest paper in the Planetary Science Journal, led by Qicheng Zhang, a PhD student at the California Institute of Technology, suggested that the close encounter of the asteroid Phaethon with the Sun led to the vaporization of the sodium within the asteroid and drive comet-like activity.
"Our analysis shows that Phaethon's comet-like activity cannot be explained by any kind of dust," said Qicheng Zhang, a California Institute of Technology PhD student who led the new study into Phaethon.
In 2009 when Phaethon reached its closest point to the Sun (or perihelion) along its orbit, NASA’s Solar Terrestrial Relations Observatory (STEREO) spotted a short tail extending from the asteroid. The tail’s appearance supported the idea that dust was escaping the asteroid’s surface when heated by the Sun.
However, in 2018, a solar mission imaged part of the Geminid debris trail and made a surprising discovery. The 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.
Scientists wondered whether something else, other than dust, was behind Phaethon’s comet-like behavior.
“Comets often glow brilliantly by sodium emission when very near the Sun, so we suspected sodium could likewise serve a key role in Phaethon’s brightening," Zhang said.
Qicheng Zhang used the Solar and Heliospheric Observatory (SOHO) spacecraft — a joint mission between NASA and the European Space Agency (ESA) – which has colour filters that can detect sodium and dust.
In SOHO’s observations, the asteroid’s tail appeared bright in the filter that detects sodium, but it did not appear in the filter that detects dust. In addition, the shape of the tail and the way it brightened as Phaethon passed the Sun matched exactly what scientists would expect if it were made of sodium, but not if it were made of dust.
This evidence indicates that Phaethon’s tail is made of sodium, not dust.
Milestone Alert!Livemint tops charts as the fastest growing news website in the world 🌏 Click here to know more.
