Judging by how humanity didn't see any of those for millennia and now three in just several years, I can propose two hypotheses:
1. Astronomers became good enough to notice them
2. These rocks are first in an incoming flood of such objects, the Universe decided to destroy humanity.
This one is coming in fast, it has an eccentricity of over 6 with the current fits. For point of reference, 1I and 2I have eccentricities of 1.2 and 3.3.
Right now it is mostly just a point on the sky, it is difficult to tell if it is active (like a comet) yet. If it is not active, IE: asteroid like, then the current observations put it somewhere between 8-22km in diameter (this depends on the albedo of the surface). From what we know, we would expect it to likely be made up of darker material meaning given that range of diameters it is more likely to be on the larger end. However if it is active, then the dust coming off can make it appear much larger than it is. As it comes in closer to the sun and starts to warm up it may become active (or more active if its already doing stuff).
It will not pass particularly close to any planet. It will be closest to the sun just before Halloween this year at 1.35 au, moving at 68 km/s (earth orbits at 29-30 km/s). It is also retrograde (IE, it is moving in the opposite direction of planetary motion), for an interstellar object this is basically random chance that this is the case.
The next couple of weeks will be interesting for a bunch of people I know.
Source: Working on my PhD in orbital dynamics and formerly wrote the asteroid simulation code used on several NASA missions: https://github.com/dahlend/kete
We updated the URL to the ABC news report as it's more understandable to lay people, at least those like me. If someone finds a better report, let us know and we'll be happy to update it.
In a thread elsewhere I saw "Interstellar Objects in the Solar System:
1. Isotropic Kinematics from the Gaia Early Data Release 3" (https://arxiv.org/pdf/2103.03289) mentioned.
In there, one estimate of the number of these objects is
Nisc <~ 7.2 × 10−5 AU−3
Which (my, probably wrong, calc) implies roughly one inside the orbital volume at the radius of Saturn's orbit at any time.
The first two were used up, empty deceleration stages of a giant alien spaceship, discarded during interstellar cruise while the rest of the assembly kept burning for its years long deceleration from relativistic speeds. This is the main ship.
Wow. The 2019 novel “The Last Astronaut” hypothesized about a fictional interstellar object coming into the solar system, called “2I” in the novel for short, but back here in real life, we’re already up to 3I.
The "popular" understanding might even be "it's aliens!". Let me pull my elitist card, but I think it's irresponsible for journalists to use the word "visit", because it implies a thinking creature performing an action. God knows this planet has too many morons who'll see this headline and understand it to be "definitely aliens!"...
How do they plot the path of these things without knowing its weight and size? Seems like bullshit, especially when they specifically say "the sun will barely affect it" ?? The sun affects everything in proportion to the things you exactly dont yet know, doesn't it?
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[ 3.8 ms ] story [ 44.0 ms ] thread1. Astronomers became good enough to notice them 2. These rocks are first in an incoming flood of such objects, the Universe decided to destroy humanity.
Right now it is mostly just a point on the sky, it is difficult to tell if it is active (like a comet) yet. If it is not active, IE: asteroid like, then the current observations put it somewhere between 8-22km in diameter (this depends on the albedo of the surface). From what we know, we would expect it to likely be made up of darker material meaning given that range of diameters it is more likely to be on the larger end. However if it is active, then the dust coming off can make it appear much larger than it is. As it comes in closer to the sun and starts to warm up it may become active (or more active if its already doing stuff).
It will not pass particularly close to any planet. It will be closest to the sun just before Halloween this year at 1.35 au, moving at 68 km/s (earth orbits at 29-30 km/s). It is also retrograde (IE, it is moving in the opposite direction of planetary motion), for an interstellar object this is basically random chance that this is the case.
Link to an orbit viewer: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3I&vi...
The next couple of weeks will be interesting for a bunch of people I know.
Source: Working on my PhD in orbital dynamics and formerly wrote the asteroid simulation code used on several NASA missions: https://github.com/dahlend/kete
The original URL was https://minorplanetcenter.net/mpec/K25/K25N12.html, which I've included in the header.
In there, one estimate of the number of these objects is
Which (my, probably wrong, calc) implies roughly one inside the orbital volume at the radius of Saturn's orbit at any time.The solar system is an interstellar highway.
Chariots Of The Gods, man.
But seriously, why would interstellar objects come towards our solar system?
It seems strange. Does gravity do that?
If there’s two within ten years then there has to be a veritable swarm of these things traveling between the stars - is that right or wrong?
Probably only Project Orion would be able to catch up to its current 60kms/s speed by October.