The 3I/Atlas approaches our planet “at an incredible speed”. According to a new study, this speed should allow it to escape the Sun’s gravitational pull, and pose no danger to Earth. Except, of course, if this speed is a sign that it is an extraterrestrial ship…
We know three interstellar objects (ISO) who visited our inner Solar System. The first was , which passed by in 2017. This was followed by , an interstellar comet detected in 2019.
And, at this moment, the interstellar comet is visiting the interior of the Solar System, heated by the Sun.
Or astronomer Avi Loeba researcher at Harvard University, suspects that , and points out 9 reasons for his suspicion. But Tom StatlerNASA’s lead scientist for small bodies in the solar system, says the object “looks like a comet, does comet things, it’s a comet“.
On the assumption that the 3I/Atlas It’s not an alien spaceship on the way to an invasion of Earth, but simply a celestial body that is passing through our solar system, What danger does it really pose? to our planet this object — and all other interstellar objects who decide to visit us?
Over the 4.6 billion year history of the Solar System, it is likely that a immense number of interstellar objects have passed by here. It is even possible that some have collided with Earthnote or .
Maybe these ISOs are responsible for some of the ancient craters of impact whose traces we can still observe today, such as the Vredefort structure, in Australia, the .
Our Solar System is today much calmer than it was in the past. In the early days, it was shaped by chaotic collisions. Currently, there are fewer rocks and fewer impacts, because much of the rocky material has aggregated to form terrestrial planets.
But The same cannot be said about ISOs. There is no reason to think that fewer interstellar objects enter the Solar System now than they did before. This means that pose an impact risk to Earth. But will it be possible quantify this risk?
In a new one, pre-published last week in arXiva team of researchers led by astronomer Darryl Seligmanda Michigan State University, try to understand precisely this.
“In this article, we calculate the expected orbital elementsthe radiants and velocities of interstellar objects that collide with Earth”, write the authors of the article.
The study does not calculate the total number of ISOsbecause there is no data that allows us to establish reliable limits for this value. The work focuses only on your expected distribution.
As for the origin of these objects, researchers focus on what they call kinematics of M-type stars.
M stars, also known as red dwarfsare the most common type in the Milky Way. It makes sense, therefore, to assume that most ISOs have been expelled of planetary systems around red dwarfs, for simple statistical reasons.
However, the authors recognize that this choice is somewhat arbitrary: “This option is, admittedly, a bit arbitrary, since the kinematics of interstellar objects are unknown,” they explain.
The researchers resorted to simulations to address the problemthe. “We generated a synthetic population of around 10¹⁰ interstellar objects with M star kinematics, in order to obtain around 10⁴ terrestrial impactors”, they write.
The simulations show that ISOs are twice as likely to come from two specific directions: the solar apex and the galactic plane.
The solar apex is the direction in which the Sun moves in relation to neighboring stars — that is, its path through the Milky Way. ISOs are more likely to come from this direction because the Solar System moves in this direction. It’s a bit like driving a car and getting more raindrops on the windshield.
Already the galactic plane is the disk-shaped region where most of the stars in the galaxy are concentrated. As this is where the most numerous star systems are located, it is also one of the areas where ISOs are most likely to to arrive. Those that approach “head on” have a larger collision section with the Earth.
The simulations also show that the ISOs coming from the solar apex and the galactic plane tend to have higher speeds.
However, and counterintuitively, those who can effectively collide with the Earth are those who present lower speedsbecause potential impactors are, in general, low eccentricity hyperbolic bodies — more susceptible to gravitational attraction of the Sun, which can deflect the slowest for trajectories that cross Earth’s orbit.
As seasons also influence the phenomenon. ISOs with the highest impact speed are most likely to arrive in the spring, when the Earth moves toward the solar apex.
However, there are more potential impactors in winterthe height at which the planet is facing the solar antiapex, the direction opposite to the Sun’s movement.
As regards the most vulnerable areas of the worldlow latitudes, close to the equator, face the highest risk. There is also a slight risk higher in the northern hemispherewhere around 90% of the human population lives.
As already mentioned, This work only applies to ISOs expelled from systems with M-type stars. “These distributions are valid only for interstellar objects with M-star kinematics. Different kinematic assumptions would alter the distributions presented in this paper,” the authors write.
Still, they believe that main identified patterns remain in other cases: “The salient features summarized in this section presumably also apply to different kinematics, perhaps with weaker or more pronounced effects”, they state.
It is important to emphasize that the study does not predict the actual number of ISOssomething that remains impossible to measure. “In this paper, we have deliberately chosen not to make definitive predictions about the impact rates of interstellar objects,” they conclude.
Right. But then, the 3I/Atlas Is it a threat to Earth or not??
According to data collected so far by astrophysicists, our third known interstellar visitor is currently crossing the solar system “at a incredible speed“, that is, according to the study by Seligman and colleagues, it will able to escape the Sun and does not represent a danger to Earth.
This, of course, if the mysterious object is a natural celestial body — because precisely This incredible speed is one of the nine reasons for which Avi Loeb suspects that it is an alien ship. And in that case, the Earth could be in danger…
