Latest in space exploration by Sky Headlines logo

Solar Observatories Reveal Comet-Like Tail is not Dust

Solar observatories have uncovered a new discovery about Asteroid 3200 Phaethon, the celestial body responsible for the annual Geminid meteor shower. It has been found that the asteroid behaves similarly to a comet, overturning previous assumptions. New Study Reveals Asteroid’s Tail is Composed of Sodium Gas, Not Dust NASA’s latest research has utilized data from two of its solar observatories, namely the Solar Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory (SOHO).  However, the study’s lead author, Qicheng Zhang, and his colleagues now believe that some sun-skirting “comets” may actually be rocky asteroids like Phaethon heated up by the Sun.

So let’s find out about,

What do solar observatories reveal about the tail of Asteroid 3200 Phaethon?

A recent study has illuminated the behavior of asteroid 3200 Phaethon, which causes the Geminid meteor shower and possesses comet-like properties. Scientists previously attributed the asteroid’s brightening and tail formation to the release of dust caused by exposure to the Sun’s heat. However, a recent study utilizing data from two NASA solar observatories has uncovered that the tail of Phaethon is, in fact, composed of sodium gas rather than dust. This discovery challenges previous assumptions and suggests that some rocky asteroids may behave similarly to comets when heated by the Sun.

Asteroids, being mainly composed of rock, typically do not exhibit the phenomenon of developing tails as they come closer to the Sun. This characteristic has been traditionally associated with comets, which are typically composed of both ice and rock and form tails when their ice is vaporized by the Sun, ejecting material from their surfaces and leaving behind a trail in their orbit. As Earth intersects with the debris trail of such comets, the resulting meteor shower occurs when the cometary fragments burn up upon entering the Earth’s atmosphere.

This illustration depicts asteroid Phaethon being heated by the Sun. The asteroid’s surface gets so hot that sodium inside Phaethon’s rock likely vaporizes and vents into space, causing it to brighten like a comet and form a tail. Credits: NASA/JPL-Caltech/IPAC


The findings were reported by Qicheng Zhang, a researcher at the California Institute of Technology and the main author of a paper published in the Planetary Science Journal. She says: “Our analysis shows that Phaethon’s comet-like activity cannot be explained by any kind of dust,” Moreover, she says: “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,”

Following the astronomers’ discovery of Phaethon in 1983, it became evident that the asteroid’s orbit was consistent with that of the Geminid meteors. Phaethon was recognized as the likely source of the yearly meteor shower despite being an asteroid.

Moreover, let’s discuss,

Observation of NASA STEREO!

This two-hour sequence of images from the Solar and Heliospheric Observatory (SOHO) shows Phaethon (circled) moving relative to background stars. The images were taken on May 15, 2022, when the 3.4-mile-wide asteroid ventured close to the Sun, at a distance of 13 million miles. While SOHO routinely observes the Sun, it also observes many objects that pass near the Sun, including comets and asteroids. The random white specks are energetic particles, or cosmic rays, that constantly bombard the SOHO camera.
Credits: ESA/NASA/USNRL/Karl Battams

In 2009, NASA’s Solar Terrestrial Relations Observatory (STEREO) made an important observation while monitoring Asteroid 3200 Phaethon. During the asteroid’s closest approach to the Sun, also known as “perihelion,” STEREO spotted a brief tail emanating from Phaethon. Traditional telescopes were not able to detect this tail as it only forms when the asteroid is too close to the Sun, making observation impossible except with specialized solar observatories like STEREO. Further solar approaches in 2012 and 2016 also allowed STEREO to witness the development of Phaethon’s tail. The emergence of the tail supported the hypothesis that dust particles were escaping the asteroid’s surface as a result of solar heating.

In 2018, a solar mission captured images of a portion of the Geminid debris trail, which led to an unexpected discovery. Data obtained from NASA’s Parker Solar Probe indicated that the trail had a significantly greater amount of material than what could be attributed to Phaethon’s proximity to the Sun.

The Sun’s high heat during Phaethon’s close solar approaches may indeed cause sodium within the asteroid to evaporate and fuel comet-like activity, according to an earlier study that was based on simulations and laboratory tests.

There is a question that arises: Is Asteroid Phaethon’s Tail Composed of Sodium Gas?

Zhang looked for the tail again during Phaethon’s last perihelion in 2022. He wanted to find out what the tail was really made of. He used the Solar and Heliospheric Observatory (SOHO) spacecraft, which is a joint project between NASA and the European Space Agency (ESA). SOHO has color filters that can find sodium and dust. Zhang’s team also looked through old STEREO and SOHO images and found Phaethon’s tail during 18 close passes to the sun between 1997 and 2022.

When Solar Observatories SOHO looked at the asteroid, its tail looked bright through the sodium filter, but it didn’t show up through the dust filter. Also, the shape of the tail and the way it got brighter as Phaethon went by the Sun were exactly what experts would expect if it were made of sodium, but not if it were made of dust.

This evidence suggests that the tail of Phaethon is composed of sodium, not detritus.

A team member of the Naval Research Laboratory Karl Battams says: “Not only do we have a really cool result that kind of upends 14 years of thinking about a well-scrutinized object,”. Battams added: “But we also did this using data from two heliophysics spacecraft – SOHO and STEREO – that were not at all intended to study phenomena like this.”

phaethon img 2
The Large Angle and Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SOHO) imaged asteroid Phaethon through different filters as the asteroid passed near the Sun in May 2022. On the left, the sodium-sensitive orange filter shows the asteroid with a surrounding cloud and small tail, suggesting that sodium atoms from the asteroid’s surface are glowing in response to sunlight. On the right, the dust-sensitive blue filter shows no sign of Phaethon, indicating that the asteroid is not producing any detectable dust. Credits: ESA/NASA/Qicheng Zhang


Scientists question whether some sun-skirting “comets” are actually rocky asteroids like Phaethon. We will be finding it out in:

How Do Asteroids Like Phaethon Supply the Material for Meteor Showers?

Zhang and his research team have raised the possibility that some sun-skirting “comets” discovered by NASA’s Solar Observatories SOHO and citizen scientists through the Sungrazer Project may not actually be comets, but rather rocky asteroids like Phaethon, which have been heated up by the Sun. Despite this new discovery, the question remains as to how Phaethon provides the material for the annual Geminid meteor shower, given that it doesn’t shed much dust. One theory suggests that a disruptive event, such as a piece of the asteroid breaking apart, caused Phaethon to eject the billion tons of material estimated to make up the Geminid debris stream. However, the exact nature of this event remains unknown.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *