Comète 3i/Atlas: older than the earth, which is this interstellar traveler who came to visit us?
COMETE 3I/ATLAS IMAGAGE on July 2 by the ITélélescope reflector of 0.51 m. © Flipp Romanov
We mentioned last week The third interstellar object discovered in our solar system. Astronomers today believe that this comet, called 3i/Atlas, would be even more special, because it could be almost twice as old than our land.
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These objects from elsewhere have only been identified for a short time and are first studied by calculating their hyperbolic trajectory. And precisely, 3i/Atlas seems to come from the thick disc of the Milky Way, known to be a hideout of very old stars, older than the sun, a fortiori the solar system.
Simulated polar view of the Milky Way. The circle in dotted yellow is the estimated trajectory of the sun, the dotted red circles represent the possible trajectories of 3i/atlas. © ESA/GAIA/DPAC, Stefan Payne-Wardenaar, CC-BY-SA 4.0
The oldest comet never discovered
3i/Atlas in motion, after its discovery on July 1. © Atlas/University of Hawaii/NASA.
To confirm the origin of this comet of approximately 10 to 20 km in diameter and rushes to almost 70 km/s, it will be necessary to analyze its light spectrum, which will make it possible to determine the proportion of certain elements, atoms and molecules, to be compared to the chemicals of formation of the galactic disc. The probable age of the comet would then be some 7 billion years.
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In a given stellar system, such as ours, all objects belonging to it actually have more or less the same age of training. The star, the planets, the comets and other asteroids come from the same original material: a gas nebula having certain chemical properties (such a proportion of hydrogen, carbon, iron, etc.). All these beautiful cosmic livestock therefore presents a kind of common genetic heritage.
Seeing thus arriving in the solar system such a distant object, formed around a star other than the sun, is an invaluable chance to learn more about our galaxy and our origins. This is the story that comes to us.
Not easy to spot 3i/Atlas with all these stars in the background… © Atlas/University of Hawaii/NASA
On the way to her perihelion, the moment when the comet is closest to the sun, scheduled for October 29, 2025, the comet will gradually warm up and emit a gas tail filled with volatile elements which will then analyze it with great precision.
Structure of a comet. © European Space Agency
Until then, we can only dream of his epic journey in the interstellar void, after a birth in a completely different galactic country, with another sun and other planets …
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