Astronomers discover 3I/ATLAS – Third interstellar object to visit Solar System

https://www.abc.net.au/news/science/2025-07-03/3i-atlas-a11pl3z-interstellar-object-in-our-solar-system/105489180

308•gammarator•7mo ago

Minor Planet Electronic Circular: https://minorplanetcenter.net/mpec/K25/K25N12.html

Comments

ordu•7mo ago

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.

em3rgent0rdr•7mo ago

hah! Yeah the title "Third Interstellar Object Discovered" needs to be changed to be more like "Third Discovery of an Interstellar Object"

noduerme•7mo ago

I love this. But I can't help imagining the conversation on some remote South Pacific island going like this:

"Third cargo chest discovered"

"Maybe they've been sailing by here already for a long time and we just didn't notice."

haiku2077•7mo ago

3. After we found the first one by chance we started looking for more objects outside the solar system's orbital plane

eesmith•7mo ago

This object is near the solar system's orbital plane - far closer than Halley's comet, for example.

People have searched off the orbital plane for a long time, if only to find new comets.

This object was found by ATLAS, the Asteroid Terrestrial-impact Last Alert System. The project goal is to identify near-earth asteroids, evaluate the risk they might impact the Earth, and alert others if impact is predicted.

The project started in 2015, two years before ʻOumuamua. It was not made specifically to find interstellar objects transiting the solar system.

metalman•7mo ago

un-nervingly near the orbital plane, as the depiction shows the object passing just above, on approach, and juct below, on departure, of the orbital plane of mars given the low relative speed of these objects so far, we can define them as extra solar, something exra galactic could be moveing at fractional light speed relative to us and be almost impossible to see and track unless it was realy big and close, and as there are confirmed exra galactic stars, it is not conjecture to to then include rouge planets and asteriods ,etc in the list of signatures to be looking for, and perhaps dismissed from previous data as bieng equipment artifacts or noise.

dotnet00•7mo ago

I get that you're joking, but I wonder if it could just be that we happen to be passing through some sort of interstellar debris cloud.

tigerlily•7mo ago

Get ready for the, uh, Latter Day Late Heavy Bombardment!

mr_toad•7mo ago

Actually we’re in a surprisingly sparse area of the galaxy, a giant hole in the galaxy created by one (or more) supernova.

https://en.wikipedia.org/wiki/Local_Bubble

stevedonovan•7mo ago

So much for the old thermonuclear ramjet idea....

kirykl•7mo ago

Maybe. The solar system was in this galactic position about 250 million years ago (one galactic year) and there was a major extinction event around that time

DevelopingElk•7mo ago

It's 1. A combination of better telescopes and GPU accelerated algorithms for picking out moving objects.

9dev•7mo ago

> These rocks are first in an incoming flood of such objects

When ʻOumuamua flew past, we should have noticed it was a passive sensor drone. Now it is too late.

shiroiuma•7mo ago

It's not "the Universe"; it's an alien race that wants to destroy us before we become a threat to them.

belter•7mo ago

We are a much bigger threat to ourselves.

phatskat•7mo ago

Yep, the best thing for a race that is (rightfully) worried about our aggressiveness is to wait it out.

lynx97•7mo ago

Came here to say that. Best to just wait and let history take its course.

nandomrumber•7mo ago

Or launch an attack fleet, only to later, due to an error in a scaling factor, have the entire fleet unknowingly swallowed by a small dog.

belter•7mo ago

https://youtu.be/smwd8b0ycBg

dguest•7mo ago

It's more complicated than that.

Benevolent aliens are planting incompetent people in positions of power so that we are perpetually on the verge of self-annihilation. But this is all to save us from the malevolent aliens who would obliterate us if they thought we had any chance of survival.

eb0la•7mo ago

I believe #1 is true; but not #2. It's just that those rocks are more common than we thought. And we thought they were uncommon because we weren't able to spot them... yet.

polytely•7mo ago

Vera Rubin just came online, will will start to do surveys of the entire sky every 3 nights, which makes spotting stuff like this easier.

https://youtu.be/X3N-DjVXh44

so we are probably gonna notice a lot more of them

TheBlight•7mo ago

We don't know if they're all rocks or not yet.

slightwinder•7mo ago

We hadn't the means to discover them for most of the last millennia, so now being good enough is obvious. But the question is why now, and not 10 or 20 years ago. It might be that we had the ability for a longer time already, but it just never "clicked" until now to recognize them. It is also possible that we really just got good enough recently. Or even that until now, there really were none in the last decade we could find, and we are just lucky(?) that now more are coming our way.

We might know this better in the next years, depending on whether there will now be an explosion of dozen and dozens of new interstellar objects discovered, or not. It might be another rush, like with exoplanets and local dwarf-planets.

jerpint•7mo ago

I know nothing about this type of data; what does it mean and how can it be interpreted as an object ?

ddahlen•7mo ago

This is an announcement from the Minor Planet Center (MPC). They are the official international clearing house for observations of solar system objects.

The top indicates that the object has two names (this is common): 3I/ATLAS = C/2025 N1 (ATLAS)

ATLAS was the telescope that made the discovery.

The list of data are individual observations of the object by different telescopes. This observation format has been in use for a long time, but is being phased out. A row is meant to fit on a single punch card...

These observations are then used to calculate orbits, the MPC calculates the orbit as well, but this list of observations is also ingested by JPL and their Horizons service.

ddahlen•7mo ago

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&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

noduerme•7mo ago

What planets is it passing between?

ddahlen•7mo 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•7mo 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•7mo 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•7mo 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•7mo ago

Also the ELT [1], I believe. (Both come online this year.)

[1] https://en.m.wikipedia.org/wiki/Extremely_Large_Telescope

cyberlimerence•7mo 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/

hermitcrab•7mo 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•7mo ago

I guess they should have SuperSized™ it.

Tuna-Fish•7mo ago

At this point, it is tradition.

https://upload.wikimedia.org/wikipedia/commons/c/c5/Comparis...

zorton•7mo ago

Not terribly related but I got curious, the ELT has a reported angular resolution of 0.005 arcseconds. The sad state of public trust has resulted in many people no longer accepting the US landed on the moon at all. Tossing the question of what it would take to resolve the lunar landing sites into a LLM gives a broad requirement of 0.0005 arcseconds. Even still, you could never "prove" it to most people unless it's glass the entire way with no "hoax generating" computers involved.

It's a fun idea thought though.

defrost•7mo ago

Good question, especially given the plane of our solar system is almost orthogonal to the greater plane of the Milky Way galaxy that contains us.

rbanffy•7mo ago

I would expect most visitors would come from the galactic plane.

noduerme•7mo 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•7mo 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•7mo ago

> It is almost on the plane of the solar system, not very inclined.

except that it's going the wrong way :)

TrainedMonkey•7mo 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•7mo ago

I would recommend staying on Earth...

jl6•7mo 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•7mo 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•7mo 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•7mo ago

In light of the error in the parent comments math, I retract my previous comment and substitute the following bit of awkward silence:

…

defrost•7mo ago

We all make mistakes, as the Dalek said climbing off the dustbin.

FWiW .. here's mine (or is it?)

One Tsar Bomba ~ 50 megatonne. One Hiroshima bomb ~ 15 kilotonne.

One Tsar Bomba ~ 50,000 / 15 ~ 3,333 Hiroshima bombs.

1,040 x Tsar Bomba ~ 3,466,667 Hiroshima bombs.

nandomrumber•7mo ago

Oops.

Every time I see your username I can’t help but say it in my mind as Defrost Kelly, some kind of frozen Dr. Leonard "Bones" McCoy

dalke•7mo ago

Imagine how I feel every time I see "Dalek" instead of my surname.

ars•7mo ago

90 m/s?

Way too slow, it's more like 70km/s (or 90) - seems you left out a k.

eesmith•7mo ago

Yes, that was my error - thanks!

perihelions•7mo ago

I can not confirm this; the parent calculation is the correct one. I can't immediately find what your error was. (edit: It's your [km/s]—you wrote [m/s] by mistake).

    (let* ((ρ ([g (cm -3)] 5))
           (d ([km] 22))
           (m (* ρ (expt d 3)))
           (v ([km (s -1)] 90))
           (ke (* 1/2 m (expt v 2)))
           (kg-tnt ([J (kg -1)] 4.2e6)))
      (values (/ ke kg-tnt)
       (as [megaton] (/ ke kg-tnt))))
    
    5.133857142857142e19 [KG]
    5.133857142857143e10 [MEGATON]

eesmith•7mo ago

My mistaken use of m/s instead of km/s, in a squared term, indeed gives a HUGE difference.

Thanks!

Voultapher•7mo ago

Based on the corrected 90 km/s instead of m/s it should be 52 pt (peta-ton) impact.

eesmith•7mo ago

Let's see if I get this math right.

Mauna Loa is about 95,000 km3 in volume says https://www.usgs.gov/volcanoes/mauna-kea/science/geology-and... . Density of TNT is 1.6g/cm3:

  95000 km3 * (1000m/km)**3 * 1600 kg/m3 = ~1.5E17 = 150 pt.

1/3rd of the mountain in TNT.

Nope, I can't conceive of that much energy.

nativeit•7mo ago

…and after just a few million years to settle down again, we’ll be ready to visit blue sky on Mars!

nandomrumber•7mo ago

Would be wild if a sufficiently large object with a lot of water and organic molecules hit Mars, ejected a lot of material in to Mars’ orbit to then go on to form a sufficiently large moon that tidally massaged Mars’ core to cause a dynamo to generate a sufficiently strong magnetic field to…

Terraform Mars!

WithinReason•7mo ago

You don't need a magnetic field to terraform Mars, it can hold onto an atmosphere without it for 100M years.

nandomrumber•7mo ago

Without a magnetic field, isn’t the surface of Mars subject to sterilising radiation from Sol?

cyberax•7mo ago

Planetary magnetic field only weakly protects against cosmic rays (extra-solar origin).

A thick enough atmosphere will stop pretty much all the charged particles from the normal solar radiation.

jajko•7mo ago

If it would be so bad, Earth's polar regions (experiencing aurora borealis) would be inhabitable too. Earth's magnetic field is not magically neutralizing all charged particles from the Sun, just diverts them (some maybe away, but many simply towards poles).

And clearly even our mag field (and Sun's heliosphere) is not enough to shield us from those crazy cosmic rays.

noduerme•7mo ago

in a somewhat related story, I was on a beach in Costa Rica last week, watching some spider monkeys in a palm tree trying to whack open small nuts. Just then, an American family walked up the beach with two teenage boys. They didn't notice the monkeys I was watching. But one of the boys grabbed a coconut off the sand and became determined to break it open with a rock in front of his parents. So watching the monkeys and the boy simultaneously, I had the distinct feeling of how slowly evolutionary, let alone geological, processes actually move.

nandomrumber•7mo ago

Haha, cool, that gave me a chuckle :)

“We'll be saying a big hello to all intelligent lifeforms everywhere and to everyone else out there, the secret is to bang the rocks together, guys.” - The Hitchhikers Guige to the Galaxy, Douglas Adams

Angostura•7mo ago

Gag Halfront, wasn’t it?

goopypoop•7mo ago

Max Quordlepleen

hermitcrab•7mo ago

Nice story.

But are you implying that we are somehow more evolved than the monkeys? Both the human and the monkey in the story have evolved for the same amount of time since our last common ancestor.

MarkusQ•7mo ago

That argument always struck me as vacuous. Dump a barrel of ball bearings on the top of a craggy hill. Wait as they all bounce around, some getting stuck in local minima and some bouncing over obstacles and covering large distances.

Would you claim that they all traveled the same distance because they all traveled for the same amount of time?

Evolutionary space is very high dimension, which makes the argument that just projecting onto the (1d) time axis is misleading even stronger.

hermitcrab•7mo ago

I'm not sure more/less evolved is a meaningful concept in Darwinian terms. Organisms have a level of fitness for their environment. Perhaps you are talking about cultural evolution?

nandomrumber•7mo ago

Do not we humans and those monkeys largely share the same environment?

Which one is more numerous, less prone to natural forcings?

tejtm•7mo ago

frame of reference matters, from the center of the sun or galactic core they all most certainly moved the same distance in the same amount of time and it was much further than the hill was tall.

MarkusQ•7mo ago

Sure? What is the analog to this other frame of reference in the evolution case though? Or are you just stepping out of the analogy's applicability range to show that it can be pushed too far (which is of course true of an analogy)?

tejtm•7mo ago

A Molecular clock would be gravity in your model, when ever you called stop all your marbles would have experienced the same amount of gravitational force. That is the intent of "experienced the same amount of evolution" and similar.

Where I see the model flounder is; the hill provides the fitness context. You implied distance "means" more evolved, but for life it is all about making it to the next round, in your marble game how many of those furthest marbles will ever be found for the next round?

With life big changes are dangerous, you may find yourself improved out of options.

belter•7mo ago

What is easier? Not mess up this planet, or Terraform Mars?

olvy0•7mo ago

Username checks out.

malfist•7mo ago

I don't know. Have you seen humanity? I think teraforming another planet is probably easier than not fucking up this one

bee_rider•7mo ago

Belter, our future is in orbital habs. Going downwell is for tourism and archaeology.

dotnet00•7mo ago

Can you walk and chew gum?

irrational•7mo ago

It’s not worth doing because it is easier, but because all of our eggs are in one basket (planet). We know of disasters that can wipe out almost all life on a single planet. Of course, there are also disasters that can wipe out all life in one star system (and one region of the Galaxy). So, ideally we need to colonize many worlds in many different parts of the Galaxy, but baby steps. Step one is to have a sustainable population on multiple moons/planets/stations of this star system before we jump to other star systems.

SoftTalker•7mo ago

Vastly easier to not only stop but also undo all the damage here than to do anything of consequence on Mars.

nandomrumber•7mo ago

Would be pretty hard to fuck up Mars’ biosphere.

vikingerik•7mo ago

The best way I heard this put: Before we worry about terraforming Mars, maybe first we should stop Venusforming Terra.

ReptileMan•7mo ago

Absolutely nothing. Way too small and slow.

nativeit•7mo ago

How fast does something need to be traveling before you’d consider it to be fast? It probably weighs as much as a city and it is traveling tens of times faster than a high-velocity bullet.

ReptileMan•7mo ago

It is of the same caliber as the dinosaur ending meteorite. The planet barely shrugged from it. There is suspicion that something the size of pluto has already hit mars once upon a time. And it is way more massive than this speck of cosmic dust.

belter•7mo 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•7mo 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•7mo ago

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

_joel•7mo 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•7mo ago

It’s going at 68km/s so I think even microbial life could be in trouble.

_joel•7mo ago

You could very well be right!

AlexGizis•7mo ago

Seems like it arrives with a bit more energy than a 10 on richter scale: https://www.edinformatics.com/inventions_inventors/richter_s...

No, I can’t really imagine what that means, either.

MaxikCZ•7mo ago

8-22km at interstellar speeds? Probably total extinction level.

ra•7mo 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•7mo 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•7mo 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•7mo 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_solarsys...

rickydroll•7mo 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

[edit] arrgh. brain spaz forgot to put in the URL

rtsil•7mo ago

> long periods of boredom

Not if it's at the speed of light, the journey will be instantaneous for the (massless) traveller.

7thaccount•7mo ago

They can't go C though, just 0.99999 C or whatever. So almost frozen in time :)

tambeb•7mo ago

I also like this solar system model from NASA, https://science.nasa.gov/learning-resources/how-big-is-the-s....

They compare it to a US football field.

"On this scale, the Sun, by far the largest thing in our solar system, is only a ball about two-thirds of an inch (17 millimeters) in diameter sitting on the goal line — that's about the width of a U.S. dime coin. ...

The inner planets — Mercury, Venus, Earth and Mars — are about the size of grains of sand on a football field scale. They would be dwarfed by a typical flea, which is about 3 millimeters long.

Closest to the goal line is Mercury, just under a yard from the end zone (.8 yards to be specific). ... At this scale, Mercury's diameter would be scarcely as large as the point of a needle.

Venus is next. It is 1.4 yards from the end zone. ...

On to Earth, sitting pretty on the 2-yard line. ...

Mars is on the three-yard line of our imaginary football field. ...

Jupiter remains pretty close to our end zone on the 10.5-yard line. ...

Saturn is on the field at 19 yards from the goal line. ...

Uranus ... is about 38 yards from our end zone.

Neptune is where things start to get way out. It is 60 yards from our solar goal line on the imaginary football field. ...

Tiny Pluto is much closer to the opposing team's end zone. It's about 79 yards out from the Sun ...

On this scale, our little friend Voyager 1 has left the game and is well out in the stadium parking lot or beyond."

dmd•7mo ago

It's illegal to mention the solar system and football without mentioning one of the greatest pieces of science fiction on the two, Jon Bois' 17776 https://en.wikipedia.org/wiki/17776

Archelaos•7mo ago

I like planetary trails, where the orbits of the planets (or other celestrial objects) are proportionally reduced and placed in the landscape.

For example, this image from a park in Halle (Germany) shows the inner solar system: https://dubisthalle.de/wp-content/uploads/2023/06/Planetenwe... -- but one has to walk 500 meters to reach Pluto.

The German Wikipedia has quite a long list of planetary trails: https://de.wikipedia.org/wiki/Planetenweg

goopypoop•7mo ago

No no no no no.

"If life is going to exist in a Universe of this size, then the one thing it cannot afford to have is a sense of proportion." -DNA

madmask•7mo ago

And the horizon you see standing on the beach is just about 5km or 3 miles away!

synlatexc•7mo ago

Primo Levi wrote a short story [1] about this. Our words/measurements are inadequate when tasked with describing the cosmos.

[1] https://www.newyorker.com/magazine/2007/02/12/a-tranquil-sta...

RcouF1uZ4gsC•7mo 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•7mo ago

I agree and I’m old enough to remember when Reddit was like this

hermitcrab•7mo ago

From the first link I get:

"specified object was not found"

What do you mean by 'active' here - has a plume?

snowwrestler•7mo 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%2F2...

slwvx•7mo ago

Yes, thanks!

ilamont•7mo 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/

treyd•7mo 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•7mo ago

We don't have enough data of the object yet to say basically anything at all about its shape.

ccgreg•7mo ago

We have numbers with a wide error bar.

accrual•7mo 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•7mo 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_interste...

somenameforme•7mo ago

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

zeristor•7mo ago

I am assuming with that the newly commissioned Vera Rubin telescope should start finding a lot more of these.

BurningFrog•7mo ago

It's built to find all of them, above a certain brightness.

We genuinely don't any idea how many it will be, so I'm hoping for a lot!

Imagine when we can get real sample material from other solar systems!

belter•7mo ago

https://en.wikipedia.org/wiki/3I/ATLAS

lionkor•7mo ago

Don't look up

Validark•7mo ago

Ahhhhhh!!!!!!!!!!!

tomhow•7mo ago

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.

The original URL was https://minorplanetcenter.net/mpec/K25/K25N12.html, which I've included in the header.

rjinman•7mo ago

The more interstellar objects we find that resemble comets, the weirder Oumuamua is.

LeoPanthera•7mo ago

The Ramans do everything in threes.

moritonal•7mo ago

Thank you! Finally a good Rama reference in the wild.

TheOtherHobbes•7mo ago

Maybe. I think it's more likely that an alien probe - assuming there are aliens and they fly probes - would be the size of a cubesat, and we wouldn't even notice it.

Perhaps Oumuamua was the mothership and the solar system is now swarming with cubesats we're not noticing.

hermitcrab•7mo ago

>I think it's more likely that an alien probe - assuming there are aliens and they fly probes - would be the size of a cubesat

Or maybe the size of a sub-atomic particle, as in the sci-fi Novel 'The 3 body problem'.

https://three-body-problem.fandom.com/wiki/Sophons

callc•7mo ago

Does anyone else see a timer ticking down in their vision or is it just me?

Time to quit my job at the LHC and be a baker.

le-mark•7mo ago

I really hope someone sends a probe to catch Omaumau. When Starship is flying regularly it should be doable, just barely.

nativeit•7mo ago

It’s news to me that Starship flying is doable.

hermitcrab•7mo ago

Can we get Musk to pilot it?

russdill•7mo ago

The chances that it's a rare type of interstellar object are incredibly small.

dgellow•7mo ago

See https://en.wikipedia.org/wiki/Project_Lyra

carlsborg•7mo ago

The great filter: light years of travel needed by detection probes.

martinclayton•7mo ago

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.

fouronnes3•7mo ago

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.

whycome•7mo ago

expand this into a sci Fi novella please

jcfrei•7mo ago

If this new 8m diameter telescope already provides us with so many new discoveries then I can't wait until the ELT with 39m diameter goes online.

sapiogram•7mo ago

ELT will not discover many new objects, it's built to do deeper followup observations of known targets. On the other hand, Vera Rubin was designed to be a survey telescope, repeatedly imaging the entire night sky to discover new objects. It will not do targeted observations, or at least very few.

aeve890•7mo ago

>Vera Rubin was designed to be a survey telescope, repeatedly imaging the entire night sky to discover new objects.

The entire _southern hemisphere_ night sky right?

sapiogram•7mo ago

Yeah, not the entire northern sky at least. It's located only 30 degrees south though, so its coverage will be pretty damn good.

andrewstuart•7mo ago

They’re always coming through.

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?

Jyaif•7mo ago

A very rough calculation would suggested that the cylinder that goes from our solar system to Proxima Centauri contains 5000 similarly sized objects moving at the same speed:

1 object crossing the solar system plane every 5 years at 60km/s

Proxima Centauri is approximately 5 light years away

there are `speed of light / 60km/s` objects in the cylinder.

hermitcrab•7mo ago

Objects can get flung out of solar systems when they pass close to large objects. Similar to how spacecraft get gravity assists.

alganet•7mo ago

> But seriously, why would interstellar objects come towards our solar system?

Why wouldn't they?

coolspot•7mo ago

Because to go through plane like that they need to match our solar system speed relative to galaxy.

alganet•7mo ago

Universe is big and full of random small rocks floating around everywhere.

Why should I believe some object was _intentionally_ thrown here? Maybe it is just one of those random rocks.

typeofhuman•7mo ago

> Floating around everywhere.

Sorry to be pedantic. But space is really, really, really... empty. That's why the best name for it is, space.

alganet•7mo ago

You can go outside at night and see big rocks floating. If space is so empty, how is it possible that you can see them with your own eyes?

We live in a patch of space that's not that empty. Maybe that interstellar rock floated from other patch of space that's not that empty all the way over here, all on its own.

Most rocks we see in our patch of space, as far as we can possibly know, were not intentionally launched.

andrewstuart•7mo ago

Because space is big. Really really big.

alganet•7mo ago

The ocean is big compared to a fish, but I can still find fish in it quite easily.

There's nothing statistically weird about these interstellar objects.

andrewstuart•7mo ago

Are we going to be able to get a close look at this?

russdill•7mo ago

Not really, the sun will be in a rather inconvenient position.

artur_makly•7mo ago

If it were to come right for us, what do we have today to stop it (if at all) ?

atrus•7mo ago

If we're just talking about interstellar objects, and assuming a decent lead time (not oh hey it's going to hit in 3 days), it's probably easier to prevent it from hitting us since it's most likely just passing through. You'd only need to give it a small enough nudge to have it miss a smidge. That's something we're more than capable now of doing, and have done.

coolspot•7mo ago

> That's something we're more than capable now of doing, and have done.

You’re very optimistic about our ability to divert 22km-diameter object moving at 70km/s .

DART smashed 680kg payload into a 780m-diameter Didymos changing its orbit.

gora_mohanty•7mo ago

We would need to detect it in time, have an interceptor fast enough to rendezvous with it, and also with enough payload to nudge it off course. Seems quite difficult with current technology

russdill•7mo ago

If this object were coming straight for Earth there would be pretty much nothing we could do to avoid a collision. Luckily the chances of such a collision are enormously small. We are fortunately bringing more resources on line to find such objects sooner.

renrutal•7mo ago

It would be neat if we could take a hitchhike with it.

Probably only Project Orion would be able to catch up to its current 60kms/s speed by October.

Klathmon•7mo ago

Given it's passing retrograde (is that even the right way to say that?), would that make it easier to catch up and intercept?

Assuming you don't want to do anything but fly by or smash into it

isx726552•7mo ago

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.

NooneAtAll3•7mo ago

tbf, Omuamua was given denomination 1I in 2017 - so it's not "reality coincided with imaginary naming", but simply "book followed real life"

m3kw9•7mo ago

It sucks to have the unpopular opinion that I wish it is aliens coming for a visit.

netsharc•7mo ago

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!"...

beefnugs•7mo ago

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?

codelikeawolf•7mo ago

When you're dealing with objects as small as this, their weight and size is essentially mathematically irrelevant. It doesn't have any type of propulsion, so we know that unless it collides with something along its trajectory, it will keep following the same course. We know the mass and diameter of the celestial bodies that the object will be traveling near, so we can calculate how those bodies will affect its trajectory. As one of the top comments said: it has a very high eccentricity, which means it's traveling along a path that forms a very elongated, open hyperbole, so it won't come close enough to the sun to be affected by its gravitational pull if it continues to follow its current trajectory.

sasikumardas•7mo ago

Interesting

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