Like a comet 3I/ATLAS continues its exciting journey through our solar system, scientists are still learning everything they can about this special space rock. It is only the second interstellar object ever to pass through our solar system, and one of the fastest comets ever observed.
How 3I/ATLAS approaches maximum distance to Earth, an international team of astronomers now says the space rock may be covered in active icy cryovolcanoes. If this is true, then the evidence detailed in their preliminary study could force researchers to reconsider how comets form—not just in deep space, but also in our solar system.
What is 3I/ATLAS?
Astronomers first discovered 3I/ATLAS in July, and since then the comet has captured the world's attention. Since then, researchers around the world have trained their telescopes and arrays of sensitive equipment on it as the comet continues its path. Travel at 130,000 mph through our star region. 3I/ATLAS offers us a never-before-seen look at ancient comets from deep space. Moreover, the icy rock never passed close enough to the star to be exposed to its heat and radiation. Essentially, this makes it an untouched cosmic artifact that is billions of years old.
Besides the fact that fastest comet ever observed (and also for sure not an alien spaceship), 3I/ATLAS also shows unexpected surface activity. After observing the guest for several months, astronomers recorded a “sharp and prolonged spike” in brightness as it reached approximately 2.5 astronomical units from the Sun (approximately 185.9 million miles). The sustained level of brightness recorded by their analysis indicates that 3I/ATLAS did not survive a sudden explosion, but rather an eruption that engulfed the entire surface layer of the comet's water ice.
Comet cryovolcanoes
They argue that the most likely explanation for this brightness is cryovolcanism. Although volcanism on Earth traditionally associated with molten lava and fiery eruptions, cryovolcanism essentially operates similarly, but with the opposite materials. During cryovolcanism, liquid and vapor water, as well as other materials, are ejected from within a cosmic body. Astronomers have I've seen this behavior on moons such as Jupiter's Europa and Saturn's Enceladus, but if confirmed, it would be a rarely seen event on comets.
Cryovolcanism at 3I/ATLAS is even more unique given the object's origins. Although the eruptions tend to be more violent, 3I/ATLAS lacks the protective dusty mantle seen on comets in our solar system. This could explain why its entire surface exploded in such a noticeable manner.
Further study of light reflected from the comet's surface revealed that 3I/ATLAS likely resembles a rare type of meteorite called carbonaceous chondrite. Carbonaceous chondrite is one of the oldest meteorites in the universeand contains large amounts of metals such as nickel and iron. This composition could explain the cryovolcanism of the comet.
The study is still awaiting peer review, but its authors suggest that as 3I/ATLAS heated up and the ice on its surface began to melt, the liquid eroded microscopic metal grains within the rock. This will subsequently release more energy and gases such as carbon dioxide, leading to a cold eruption.
Challenging the Standard Model
If this is true, then 3I/ATLAS contradicts the standard model of comet formation. Instead of a more uniform combination of rock, ice and a little metal, comets can begin their lives under much more varied circumstances.
“Interstellar visitors such as 3I/ATLAS continue to challenge and advance our understanding of the formation of planetary systems and the chemical evolution of small bodies,” he said. the study authors wroteadding that “each newly discovered object reveals unexpected properties that test and extend existing models.”
