9 ms·

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

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. Link to an orbit viewer: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=3I&view=VOP 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 https://github.com/dahlend/kete

noduerme 1y ago
What planets is it passing between?
- ddahlen 1y ago
  It is inside jupiter's orbit now, it will come inside Mars for a time. It is almost on the plane of the solar system, not very inclined. I linked an orbit viewer above if you want to look.
  - Teever 1y ago
    > It is almost on the plane of the solar system, not very inclined. Is this also random chance or is there a reason why it's so close to the plane of the solar system?
    - ddahlen 1y ago
      It is also a factor of where our surveys look on the sky. A lot of asteroid surveys have biases to look at the plane of our solar system (since this is where a lot of asteroids are). It is probably random chance, however there may be some biases from where they come from on the sky (I know people who work on that, but I don't know much about it). N=3 does not provide very robust statistics yet, give us another decade or two.
      - sgt101 1y ago
        We're going to see a lot more of these in the next couple of years due to the new Vera C Rubin observatory.
        JumpCrisscross 1y ago
        Also the ELT [1], I believe. (Both come online this year.) [1] https://en.m.wikipedia.org/wiki/Extremely_Large_Telescope https://en.m.wikipedia.org/wiki/Extremely_Large_Telescope
        cyberlimerence 1y ago
        ELT's first light is planned for March 2029.[1] Vera is already online I think. [1] https://www.eso.org/public/announcements/ann25001/ https://www.eso.org/public/announcements/ann25001/
        hermitcrab 1y ago
        I can't believe that all those super-intelligent astronomers, who spend hours on their own in the dark, couldn't come up with a better name than 'Extremely Large Telescope'. ;0)
        mcswell 1y ago
        I guess they should have SuperSized™ it.
        1y ago
  - noduerme 1y ago
    Huh. It looks like on 10/2 it will make its closest pass to a planet, Mars, and on that date it also is in a straight line with Mars, Mercury and the sun, while Earth and Venus are roughly opposite each other. Do you know if this sim accounts for solar or martian gravity diverting its trajectory?
    - ddahlen 1y ago
      This orbit visualization uses a simple 2 body approximation, so only the sun. This is because unless an object has a VERY close approach to a planet the two body approximation is more then enough for this style of visualization. I did a full proper n-body integration and it is not visually different than this.
  - NooneAtAll3 1y ago
    > It is almost on the plane of the solar system, not very inclined. except that it's going the wrong way :)
TrainedMonkey 1y ago
From the simulation you linked looks like it is passing closeish to the Mars... but I do know that space is big. However, I am curious of what would happen if an object of this magnitude hit mars at 90km/s.
- ddahlen 1y ago
  I would recommend staying on Earth...
- jl6 1y ago
  Assuming it’s at the upper range of the size estimate above, and of average rocky density, the kinetic energy of the impact would be something like a 10 billion megaton nuke. If we could steer it to hit one of Mars’s poles, it might do a bit of terraforming for us!
  - eesmith 1y ago
    Where did my math go wrong? I got about 50,000 megatons. Assuming the high-end of 22km and a rocky/metallic density of 5000 kg/cubic meter (and assuming it's a cube): kinetic energy = 1/2 m v**2 = 1/2 * size * density * v**2 = 1/2 *(22000 m)**3 * (5000 kg/m**3) * (90 m/s)**2 / (4.184E15 J/megaton) = 52,000 megaton If it's an icy comet then the density is more like 500 kg/cubic meter, or 1/10th that number.
    - nandomrumber 1y ago
      1040 x more energy that the Tsar Bomba. Or 5-ish Tsar Bomba per country on Earth. Or 3466 Hiroshima nukes. Or 17 Hiroshima nukes per country.
      - nandomrumber 1y ago
        In light of the error in the parent comments math, I retract my previous comment and substitute the following bit of awkward silence: …
belter 1y ago
Are you able to calculate whether, by any chance, it will come close to any of the NASA probes around Jupiter, Mars, Venus, etc...? What is its closest approach to the JWST?
- ddahlen 1y ago
  The closest it will come is Mars, but when I say close these are quite literally astronomical distances, about 0.2 au from Mars. This is about 75x further than the moon is from the Earth. If it is an inactive rock, then we will not see it as any more than a point of light during its visit.
tvickery 1y ago
I know it’s incredibly, vanishingly unlikely but what would happen if an object with these characteristics smacked into Earth?
- _joel 1y ago
  The end, unless you're a small proto-mammal ;). An object (depending on consistency) of about 100m is enough to wipe out a city and do enough damage to the environment. Something of 8-20km is in the same category as what wiped out the dinosaurs (10-15km).
  - padjo 1y ago
    It’s going at 68km/s so I think even microbial life could be in trouble.
    - _joel 1y ago
      You could very well be right!
  - AlexGizis 1y ago
    Seems like it arrives with a bit more energy than a 10 on richter scale: https://www.edinformatics.com/inventions_inventors/richter_scale.htm https://www.edinformatics.com/inventions_inventors/richter_s... No, I can’t really imagine what that means, either.
- MaxikCZ 1y ago
  8-22km at interstellar speeds? Probably total extinction level.
- ra 1y ago
  With this much mass and velocity - it would smash the planet, rupturing the entire crust at the very least. No matter how infinitesimally small the probability - the universe is infinite, and so it probably will happen. i3 is much bigger than the Chicxulub asteroid that ended the Cretaceous period (and extinct all non-avian dinosaurs).
TMEHpodcast 1y ago
Closest approach will be October 29, 2025. It’s currently passing Jupiter’s orbit. I’m amazed that even at this speed it will take that long to get here. “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is.” ~Douglas Adams
- bee_rider 1y ago
  Sometimes it is hard to think of big space is, especially because we tend to do that while sitting around inside (this is where we have most of our thoughts, after all). Of course space distances are nothing like the distances inside our rooms, no frame of reference. Instead, go out to the ocean on a clear day, and observe how absurdly vast the ocean is. Just ocean, as far as you can see. Look around and realize you’ve gained absolutely nothing in terms of comprehending the vastness of space, to which the difference between your room and the most sweeping views on Earth are just totally insignificant.
  - GolfPopper 1y ago
    The single best depiction of the Solar System to help grok size and distance is Josh Worth's "If the Moon were only 1 pixel": https://www.joshworth.com/dev/pixelspace/pixelspace_solarsystem.html https://www.joshworth.com/dev/pixelspace/pixelspace_solarsys...
    - rickydroll 1y ago
      An even better visualization of the size of the Solar System. It shows traveling from the Sun out to forever at the speed of light. Be prepared to spend hours watching the paint dry. I suspect traveling in space will be like war, long periods of boredom punctuated by brief moments of sheer terror. https://www.youtube.com/watch?v=1AAU_btBN7s https://www.youtube.com/watch?v=1AAU_btBN7s [edit] arrgh. brain spaz forgot to put in the URL
      - rtsil 1y ago
        > long periods of boredom Not if it's at the speed of light, the journey will be instantaneous for the (massless) traveller.
RcouF1uZ4gsC 1y ago
> Source: Working on my PhD in orbital dynamics and formerly wrote the asteroid simulation code used on several NASA missions: This is one of the big reasons I love HN
- TMEHpodcast 1y ago
  I agree and I’m old enough to remember when Reddit was like this
hermitcrab 1y ago
From the first link I get: "specified object was not found" What do you mean by 'active' here - has a plume?
- snowwrestler 1y ago
  I found it by searching an alternate designation: C/2025 N1 Edit: does this link work? https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=C%2F2025%20N1 https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=C%2F2...
  - slwvx 1y ago
    Yes, thanks!
ilamont 1y ago
Thanks for sharing this info. Does "eccentricity" refer to the orbit, or the shape of the object? For ‘Oumuamua in 2017, some method was used to determine its shape, which is (apparently) remarkably elongated. Is it possible to determine the elongation of the new object? https://science.nasa.gov/solar-system/comets/oumuamua/ https://science.nasa.gov/solar-system/comets/oumuamua/
- treyd 1y ago
  Eccentricity refers to the shape of the orbit, derivable from the highest and lowest distances in the orbit of the orbiting body (there's actually a bunch of ways to calculate it that are mathematically equivalent). It's related to modeling orbits as conic sections. An eccentricity of 0 is a perfect circle, <1 is a normal elliptical orbit, >=1 is an escaping trajectory. For example, Earth's orbit around the sun is ~0.0167, Pluto's is 0.248.
- Tuna-Fish 1y ago
  We don't have enough data of the object yet to say basically anything at all about its shape.
  - ccgreg 1y ago
    We have numbers with a wide error bar.
- accrual 1y ago
  To add what others said, eccentricity is also a way to tell if the object is captured or not. 0 means perfectly circular orbit, >=1 means escape, >=2 means hyperbolic.
bbor 1y ago
Thanks for sharing your expertise! What really bends my mind is the relative speeds involved. Reddit's /r/space has a great visual[1] which depicts it as basically going straight through our solar system, only bending slightly as it passes Sol. This is only possible if the object moving at 68 km/s is also moving sideways at 230 km/s so as to match our galactic orbit, and moving up at a mind-boggling 600 km/s (relative to CMB). This is all basic stuff of course, but something about having the object actually pass by us is making it more real than usual... Hell, maybe it's only orbiting the galaxy at a leisurely 160 km/s, and from its perspective we're a spinning disc of chaos zipping past it for the first time in a few million years! I don't even know how I would start to analyze its orientation in relation to the galactic center, but I'll be keeping this as my little "headcannon" until proven wrong, that's for sure. [1] https://www.reddit.com/r/space/comments/1lpw4as/new_interstellar_object_candidate_heading_toward/ https://www.reddit.com/r/space/comments/1lpw4as/new_interste...
somenameforme 1y ago
Getting a "specified object not found" on the orbit viewer.

noduerme 1y ago

What planets is it passing between?

ddahlen 1y ago
It is inside jupiter's orbit now, it will come inside Mars for a time. It is almost on the plane of the solar system, not very inclined. I linked an orbit viewer above if you want to look.
- Teever 1y ago
  > It is almost on the plane of the solar system, not very inclined. Is this also random chance or is there a reason why it's so close to the plane of the solar system?
  - ddahlen 1y ago
    It is also a factor of where our surveys look on the sky. A lot of asteroid surveys have biases to look at the plane of our solar system (since this is where a lot of asteroids are). It is probably random chance, however there may be some biases from where they come from on the sky (I know people who work on that, but I don't know much about it). N=3 does not provide very robust statistics yet, give us another decade or two.
    - sgt101 1y ago
      We're going to see a lot more of these in the next couple of years due to the new Vera C Rubin observatory.
      - JumpCrisscross 1y ago
        Also the ELT [1], I believe. (Both come online this year.) [1] https://en.m.wikipedia.org/wiki/Extremely_Large_Telescope https://en.m.wikipedia.org/wiki/Extremely_Large_Telescope
        cyberlimerence 1y ago
        ELT's first light is planned for March 2029.[1] Vera is already online I think. [1] https://www.eso.org/public/announcements/ann25001/ https://www.eso.org/public/announcements/ann25001/
        hermitcrab 1y ago
        I can't believe that all those super-intelligent astronomers, who spend hours on their own in the dark, couldn't come up with a better name than 'Extremely Large Telescope'. ;0)
        mcswell 1y ago
        I guess they should have SuperSized™ it.
        1y ago
- noduerme 1y ago
  Huh. It looks like on 10/2 it will make its closest pass to a planet, Mars, and on that date it also is in a straight line with Mars, Mercury and the sun, while Earth and Venus are roughly opposite each other. Do you know if this sim accounts for solar or martian gravity diverting its trajectory?
  - ddahlen 1y ago
    This orbit visualization uses a simple 2 body approximation, so only the sun. This is because unless an object has a VERY close approach to a planet the two body approximation is more then enough for this style of visualization. I did a full proper n-body integration and it is not visually different than this.
- NooneAtAll3 1y ago
  > It is almost on the plane of the solar system, not very inclined. except that it's going the wrong way :)

TrainedMonkey 1y ago

From the simulation you linked looks like it is passing closeish to the Mars... but I do know that space is big. However, I am curious of what would happen if an object of this magnitude hit mars at 90km/s.

ddahlen 1y ago
I would recommend staying on Earth...
jl6 1y ago
Assuming it’s at the upper range of the size estimate above, and of average rocky density, the kinetic energy of the impact would be something like a 10 billion megaton nuke. If we could steer it to hit one of Mars’s poles, it might do a bit of terraforming for us!
- eesmith 1y ago
  Where did my math go wrong? I got about 50,000 megatons. Assuming the high-end of 22km and a rocky/metallic density of 5000 kg/cubic meter (and assuming it's a cube): kinetic energy = 1/2 m v**2 = 1/2 * size * density * v**2 = 1/2 *(22000 m)**3 * (5000 kg/m**3) * (90 m/s)**2 / (4.184E15 J/megaton) = 52,000 megaton If it's an icy comet then the density is more like 500 kg/cubic meter, or 1/10th that number.
  - nandomrumber 1y ago
    1040 x more energy that the Tsar Bomba. Or 5-ish Tsar Bomba per country on Earth. Or 3466 Hiroshima nukes. Or 17 Hiroshima nukes per country.
    - nandomrumber 1y ago
      In light of the error in the parent comments math, I retract my previous comment and substitute the following bit of awkward silence: …

belter 1y ago

Are you able to calculate whether, by any chance, it will come close to any of the NASA probes around Jupiter, Mars, Venus, etc...? What is its closest approach to the JWST?

ddahlen 1y ago
The closest it will come is Mars, but when I say close these are quite literally astronomical distances, about 0.2 au from Mars. This is about 75x further than the moon is from the Earth. If it is an inactive rock, then we will not see it as any more than a point of light during its visit.

tvickery 1y ago

I know it’s incredibly, vanishingly unlikely but what would happen if an object with these characteristics smacked into Earth?

_joel 1y ago
The end, unless you're a small proto-mammal ;). An object (depending on consistency) of about 100m is enough to wipe out a city and do enough damage to the environment. Something of 8-20km is in the same category as what wiped out the dinosaurs (10-15km).
- padjo 1y ago
  It’s going at 68km/s so I think even microbial life could be in trouble.
  - _joel 1y ago
    You could very well be right!
- AlexGizis 1y ago
  Seems like it arrives with a bit more energy than a 10 on richter scale: https://www.edinformatics.com/inventions_inventors/richter_scale.htm https://www.edinformatics.com/inventions_inventors/richter_s... No, I can’t really imagine what that means, either.
MaxikCZ 1y ago
8-22km at interstellar speeds? Probably total extinction level.
ra 1y ago
With this much mass and velocity - it would smash the planet, rupturing the entire crust at the very least. No matter how infinitesimally small the probability - the universe is infinite, and so it probably will happen. i3 is much bigger than the Chicxulub asteroid that ended the Cretaceous period (and extinct all non-avian dinosaurs).

TMEHpodcast 1y ago

Closest approach will be October 29, 2025. It’s currently passing Jupiter’s orbit. I’m amazed that even at this speed it will take that long to get here. “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is.” ~Douglas Adams

bee_rider 1y ago
Sometimes it is hard to think of big space is, especially because we tend to do that while sitting around inside (this is where we have most of our thoughts, after all). Of course space distances are nothing like the distances inside our rooms, no frame of reference. Instead, go out to the ocean on a clear day, and observe how absurdly vast the ocean is. Just ocean, as far as you can see. Look around and realize you’ve gained absolutely nothing in terms of comprehending the vastness of space, to which the difference between your room and the most sweeping views on Earth are just totally insignificant.
- GolfPopper 1y ago
  The single best depiction of the Solar System to help grok size and distance is Josh Worth's "If the Moon were only 1 pixel": https://www.joshworth.com/dev/pixelspace/pixelspace_solarsystem.html https://www.joshworth.com/dev/pixelspace/pixelspace_solarsys...
  - rickydroll 1y ago
    An even better visualization of the size of the Solar System. It shows traveling from the Sun out to forever at the speed of light. Be prepared to spend hours watching the paint dry. I suspect traveling in space will be like war, long periods of boredom punctuated by brief moments of sheer terror. https://www.youtube.com/watch?v=1AAU_btBN7s https://www.youtube.com/watch?v=1AAU_btBN7s [edit] arrgh. brain spaz forgot to put in the URL
    - rtsil 1y ago
      > long periods of boredom Not if it's at the speed of light, the journey will be instantaneous for the (massless) traveller.

RcouF1uZ4gsC 1y ago

> Source: Working on my PhD in orbital dynamics and formerly wrote the asteroid simulation code used on several NASA missions: This is one of the big reasons I love HN

TMEHpodcast 1y ago
I agree and I’m old enough to remember when Reddit was like this

hermitcrab 1y ago

From the first link I get: "specified object was not found" What do you mean by 'active' here - has a plume?

snowwrestler 1y ago
I found it by searching an alternate designation: C/2025 N1 Edit: does this link work? https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=C%2F2025%20N1 https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=C%2F2...
- slwvx 1y ago
  Yes, thanks!

ilamont 1y ago

Thanks for sharing this info. Does "eccentricity" refer to the orbit, or the shape of the object? For ‘Oumuamua in 2017, some method was used to determine its shape, which is (apparently) remarkably elongated. Is it possible to determine the elongation of the new object? https://science.nasa.gov/solar-system/comets/oumuamua/ https://science.nasa.gov/solar-system/comets/oumuamua/

treyd 1y ago
Eccentricity refers to the shape of the orbit, derivable from the highest and lowest distances in the orbit of the orbiting body (there's actually a bunch of ways to calculate it that are mathematically equivalent). It's related to modeling orbits as conic sections. An eccentricity of 0 is a perfect circle, <1 is a normal elliptical orbit, >=1 is an escaping trajectory. For example, Earth's orbit around the sun is ~0.0167, Pluto's is 0.248.
Tuna-Fish 1y ago
We don't have enough data of the object yet to say basically anything at all about its shape.
- ccgreg 1y ago
  We have numbers with a wide error bar.
accrual 1y ago
To add what others said, eccentricity is also a way to tell if the object is captured or not. 0 means perfectly circular orbit, >=1 means escape, >=2 means hyperbolic.

bbor 1y ago

Thanks for sharing your expertise! What really bends my mind is the relative speeds involved. Reddit's /r/space has a great visual[1] which depicts it as basically going straight through our solar system, only bending slightly as it passes Sol. This is only possible if the object moving at 68 km/s is also moving sideways at 230 km/s so as to match our galactic orbit, and moving up at a mind-boggling 600 km/s (relative to CMB). This is all basic stuff of course, but something about having the object actually pass by us is making it more real than usual... Hell, maybe it's only orbiting the galaxy at a leisurely 160 km/s, and from its perspective we're a spinning disc of chaos zipping past it for the first time in a few million years! I don't even know how I would start to analyze its orientation in relation to the galactic center, but I'll be keeping this as my little "headcannon" until proven wrong, that's for sure. [1] https://www.reddit.com/r/space/comments/1lpw4as/new_interstellar_object_candidate_heading_toward/ https://www.reddit.com/r/space/comments/1lpw4as/new_interste...

somenameforme 1y ago

Getting a "specified object not found" on the orbit viewer.