Also habe ich diesen Artikel gerade gelesen
https://bohring.substack.com/p/the-story-of-interstellar-comet-3iatlas
Briefing über den neu entdeckten Kometen 3i/Atlas. Dieser Artikel (schauen Sie sich einmal einmal an) nicht erklären, wie wir wissen, dass solche Objekte interstellar sind. Könnte mir das bitte jemand erklären?
How do we know 3I/ATLAS is an interstellar object?
byu/No-Preparation7618 inspace
6 Kommentare
They go faster than an object that is orbiting the sun.
Generally, Direction its coming from, velocity, and trajectory.
Typically objects that originate from within the solar system, specifically the oort cloud where normal Comets come from won’t have velocity to escape the gravity of the Sun.
TLDR: it’s going too fast to orbit the sun and on the wrong type of trajectory to have originated from a solar orbit, and since the equations that govern these things are known we know the math doesn’t work for anything but interstellar
Easiest way to tell is its velocity. It’s traveling way faster than the escape velocity of the solar system (68 km/s vs 42 km/s), which means it’s not gravitationally bound to the sun
https://en.wikipedia.org/wiki/Specific_orbital_energy exceeds zero and https://en.wikipedia.org/wiki/Orbital_eccentricity is greater than 1.
Took astronomers a little bit of time to discern this though – it’s easy to measure angular velocity across our sky, but rather trickier to get a proper position and velocity vector in the reference frame of sun, [ecliptic](https://en.wikipedia.org/wiki/Ecliptic#Plane_of_the_Solar_System), and [FPA](https://en.wikipedia.org/wiki/First_point_of_Aries) necessitating many different measurements of position over some time to narrow down the orbital parameters.
The „orbit“ of that object has an eccentricity of 6.1 (hyperbolic). To orbit the sun, it would have to be smaller than 1: https://en.m.wikipedia.org/wiki/Orbital_eccentricity
The eccentricity (e) tells you how much the shape of the orbit deviates from a perfect circle (e = 0). Elliptical orbits have an eccentricity between 0 and 1, where exactly 1 is a parabola.