‘Statistically what is the chance that a comet would be on an ecliptic trajectory toward a planet?’

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I was wondering about this as I sipped my mushroom soup at lunchtime today, because the interstellar object 3I/ATLAS, which is not precisely aligned with the ecliptic plane, has an orbital plane that is inclined by approximately 5 degrees relative to the ecliptic, and is on a retrograde trajectory (orbiting in the opposite direction to the planets).  My laymans’ understanding is that this low inclination, is considered highly unusual for a random interstellar object, and is one of several ‘anomalies’ that have led some scientists, such as Harvard Professor Avi Loeb, to speculate about an artificial origin. In diameter, object 3I/ATLAS is about the size of Manhattan.

So, I asked AI …

AI replied – ‘The statistical chance of a random long-period comet being on a trajectory precisely aligned with the ecliptic plane (the plane in which the planets orbit) toward a planet is extremely low, essentially negligible as a random event. 

This low probability is due to two main factors: 

  • Orbital Inclination: Long-period comets, originating from the spherical Oort Cloud, have orbits that are oriented in random angles to the ecliptic plane, with inclinations distributed in all directions. In contrast, short-period comets, from the Kuiper belt, tend to have orbits closer to the ecliptic plane (within about 30 degrees).
  • Target Size: Planets are extremely small targets in the vastness of the solar system, making a direct collision path highly improbable for any single, randomly-oriented comet. 

For a known, Earth-crossing long-period comet, the average impact probability with Earth per perihelion passage is estimated to be around

2.2×10−9

(about 1 in 454 million). This probability is for any Earth-crossing orbit, most of which are not perfectly ecliptic. 

A specific interstellar object, 3I/ATLAS, was noted for having a trajectory aligned with the ecliptic plane to within five degrees, an alignment that was calculated to have a mere 0.2 percent likelihood of happening by chance, highlighting how unusual such an alignment is for a randomly incoming object. 

In essence, while comet impacts do happen over geologic timescales (the last major impact that caused global catastrophe was 65 million years ago, likely an asteroid) and have been observed on other planets (like Comet Shoemaker-Levy 9 hitting Jupiter in 1994), the chance of a random comet just happening upon an ecliptic, planet-bound trajectory is practically zero.’

My further Q. – ‘Is 3I Atlas on a trajectory precisely aligned with the ecliptic plane?’

AI – ‘No, the interstellar object 3I/ATLAS is not precisely aligned with the ecliptic plane. Its orbital plane is inclined by approximately 5 degrees relative to the ecliptic, and it is on a retrograde trajectory (orbiting in the opposite direction to the planets). 

This low inclination is considered highly unusual for a random interstellar object and is one of several anomalies that have led some scientists, such as Harvard professor Avi Loeb, to speculate about an artificial origin. 

Key Details

  • Inclination: The orbit is tilted by about 5 degrees from the ecliptic plane. In orbital terms, this is often expressed as an inclination of approximately 175 degrees (180 degrees is a perfectly retrograde orbit along the same plane as the ecliptic).
  • Significance: While 5 degrees is a small tilt compared to the other two interstellar objects discovered (1I/’Oumuamua and 2I/Borisov had inclinations of approximately 44° and 57° respectively), the statistical probability of such a close alignment occurring by chance for a randomly oriented interstellar visitor is estimated to be very low (around 0.2%).
  • Controversy: Critics argue that this apparent alignment might be due to observational bias, as most telescopes capable of discovering such objects primarily scan the sky near the ecliptic plane, where Earth’s own solar system objects are found. 

The trajectory will bring 3I/ATLAS close to Mars, Venus, and Jupiter, but it poses no threat to Earth. …

3I/ATLAS is an interstellar object because its extremely fast speed and highly hyperbolic orbit prove it’s not gravitationally bound to our Sun, but is just passing through from another star system, making it a true “outsider” carrying clues from beyond our cosmic neighborhood, unlike our Sun’s native bodies. It’s the third such object discovered, following ʻOumuamua and 2I/Borisov, and scientists confirm its icy, comet-like nature through its dust/gas coma, not alien technology. Key Reasons it’s Interstellar:

  • Hyperbolic Trajectory: Its path is an open curve (a hyperbola), meaning it won’t loop back; it’s just a visitor on its way out.
  • Extreme Velocity: It’s traveling too fast to have been captured by the Sun’s gravity, indicating it came from deep interstellar space.
  • Origin Outside Our Solar System: Tracing its orbit backwards shows it originates from outside our solar system’s boundaries. 

What it Is (and Isn’t):

  • A Comet: Observations show it’s active, releasing gas and dust (a coma and tail), classifying it as a comet.
  • Not Alien Tech: Despite some theories, scientific consensus confirms 3I/ATLAS is a natural icy visitor, providing rare insights into other planetary systems. 

Significance:

  • It’s the third interstellar visitor (after ‘Oumuamua and 2I/Borisov).
  • It’s a time capsule, carrying material from another star system, giving scientists clues about distant planet formation.’

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