In July this year, NASA’s Atlas telescope identified an object of unknown origin “walking” around Jupiter’s orbit. After analysis, researchers concluded that it is an interstellar comet — that is, coming from outside the Solar System — which would have penetrated the region of planets that orbit the Sun at an impressive speed of 221 thousand kilometers per hour.
The comet, named 3I/Atlas, caught the attention of scientists because it is only the third interstellar celestial body ever recorded “passing through” the Solar System. Before him, “‘Oumuamua” in 2017, and “2I/Borisov” in 2019, had already been discovered.
The echo of the “chemistry of life” in other planetary systems
According to researchers’ estimates, 3I/Atlas has a diameter of “no less than 440 meters and no more than 5.6 kilometers”. Additionally, unlike its two predecessors, 3I/Atlas is composed of water. This is a fundamental characteristic for studying the activity of interstellar comets and other galaxies.
“Every interstellar comet so far has been a surprise,” says researcher and one of the study’s authors, Zexi Xing, from Auburn University, in the USA. “‘Oumuamua was dry, Borisov was rich in carbon monoxide, and now 3I/Atlas is ‘gushing’ water at a distance we didn’t expect. Each is rewriting what we thought we knew about how planets and comets form around stars,” Xing revealed in a statement sent to the press.
“When we detect water, or even the ultraviolet echo from an interstellar comet, we are reading data from another planetary system,” highlights Auburn physics professor Dennis Bodewits. “This tells us that the ingredients of the ‘chemistry of life’ are not unique to our [sistema solar]”, he adds.
Asteroid or comet?
From the telescope observations, astronomers can tell that 3I/Atlas is active. This means it has an icy core and a coma (bright cloud of gas and dust that surrounds a comet as it approaches the Sun).
This is why astronomers categorize it as a comet rather than an asteroid.
How did scientists discover that 3I/Atlas did not arise from the cosmic dust of the Solar System?
For two reasons: The first of these is its high speed, which shows that the comet is not limited by the Sun’s gravity. The other feature that “gave away” the unknown origin of 3I/Atlas is its hyperbolic trajectory.
In other words, this means that its trajectory is not tied to the Sun’s orbit. And that, in the coming months, the comet will be launched out of our Solar System, disappearing into interstellar space.
“No one knows where the comet came from. It’s like glimpsing a rifle bullet for a thousandth of a second. It’s impossible to accurately project where its path began,” said researcher David Jewitt, leader of the Hubble Space Telescope science team, also responsible for monitoring 3I/Atlas. The statement was given to the Canadian television channel CBC.
Not moment, the comet is no longer visible from Earth, even with the use of telescopes or other equipment. But it should appear on the other side of the Sun in early December, allowing new observations.
Is 3I/Atlas a threat to Earth?
Several theories emerged after the announcement of the discovery of 3I/Atlas, from alien invasions to spy probes and even a possible collision with Earth. But scientists assure: there is no reason to worry.
Although the object’s trajectory brings it to the inner solar system (the region closest to the Sun, where planets such as Mercury, Venus, Mars and Earth are located), comet 3I/Atlas will not come closer than 1.8 astronomical units (about 270 million kilometers) to planet Earth.
