On July 1, the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert System) survey telescope in Rio Hurtado, Chile, first reported observations of a comet that originated from interstellar space. Arriving from the direction of the constellation Sagittarius, the interstellar comet has been officially named 3I/ATLAS. It is currently located about 420 million miles (670 million kilometers) away.
Very cool. Makes me wonder how much of that stuff we never see that is out there?
I’m sure it’s a lot. Think of the long trip it’s made.
More info and observatory’s “video”.
Norris pointed to modeling estimating that there could be as many as 10,000 interstellar objects drifting through the solar system at any given time, though most would be smaller than the newly discovered object.
That is actually more than I thought (not sure how small they are going though).
I thought I had once posted a more detailed response on this topic before. I found it here:
And from the Wikipedia article I linked:
Astronomers estimate that several interstellar objects of extrasolar origin (like ʻOumuamua) pass inside the orbit of Earth each year,[11] and that 10,000 are passing inside the orbit of Neptune on any given day.[12]
Interstellar comets occasionally pass through the inner Solar System[1] and approach with random velocities, mostly from the direction of the constellation Hercules because the Solar System is moving in that direction, called the solar apex.[13] Until the discovery of ʻOumuamua, the fact that no comet with a speed greater than the Sun’s escape velocity[14] had been observed was used to place upper limits to their density in interstellar space. A paper by Torbett indicated that the density was no more than 1013 (10 trillion) comets per cubic parsec.[15] Other analyses, of data from LINEAR, set the upper limit at 4.5×10−4/AU3, or 1012 (1 trillion) comets per cubic parsec.[2] A more recent estimate by David C. Jewitt and colleagues, following the detection of ʻOumuamua, predicts that “The steady-state population of similar, ~100 m scale interstellar objects inside the orbit of Neptune is ~1×104, each with a residence time of ~10 years.”[16]
That’ll depend on how big it needs to be before you call it an “object”. You probably don’t want to count dust grains, and you probably do want to count things the size of a comet, but there’s no clear, discrete cutoff size in between them.
Read my next post any you’ll see it is objects above 100 m.
Hey! You other solar systems, keep your trash outta our region.
My thoughts exactly. Whatever was once between Jupiter and Mars and essentially Jupiters’ gravity broke it up. Thus the Asteroid belt.
And the Russians were the first to film the other side of the Moon and really every astro-type-person was amazed at how much more impact it had taken, compared to the side of Moon that we see.
We (meaning nine billion people) are capable of dealing with known asteroids/comets that might come pretty close to earth.
These out-of-solar-system objects are great that we have (and have not de-funded) the tech and generally a miniscule chance that it’s headed to the third rock from the sun.
Yet we do or we don’t have the ability to do anything about them. Blowing up shit in space is tantamount to blowing up Beijing.
Or more precisely, prevented it from coalescing in the first place. Not that there was ever all that much there to begin with. Ceres all by itself is over a third of the total mass.
The Ramans do everything in threes.
Dunno that we know much about the Asteroid belt other than what we might surmise from Saturn’s creation of the “rings”
I am not an astrophycist (and even if I had a phD would that be enough?) yet I don’t know if it’s been determined the asteroids ever accreted into a body that Jupiter’s gravity would then destroy or if they are just rocks that Jupiter would not allow. I mean: Gravity: How does it work?
It is good that we can detect interstellar objects flying into the solar system proper, and hopefully add to our knowledge. What and why are these things flying interstellar? It’s possible for the gas giants or the sun to “grab” these things yet would likely be in a highly elliptical orbit that never comes close to the third rock.
What does the asteroid belt have to do with this topic? This is an object that came from outside the solar system, not from the asteroid belt. And it’s a comet, not an asteroid.
We have no idea what it is yet. Whether it should be called an asteroid or a comet depends on how much of it is made up of volatiles.
Well, the NASA page linked in the OP unequivocally calls it a comet, so I assumed that they have some evidence for such nomenclature.
I see that more recent observations support that
Initial observations of 3I/ATLAS were unclear on whether it is an asteroid or a comet.[13][15][6] Observations on 2 July 2025 by the Deep Random Survey (X09) at Chile, Lowell Discovery Telescope (G37) at Arizona, and Canada–France–Hawaii Telescope (T14) at Mauna Kea showed a marginal coma and a short tail 3 arcseconds in angular length, which indicated the object is a comet.[2][16] On the other hand, various astronomers including Alan Hale reported no cometary features on 3I/ATLAS.[16] On 2 July 2025, the MPC announced the discovery of 3I/ATLAS and gave it the interstellar object designation “3I”, signifying it being the third interstellar object confirmed.[2][16] The MPC also gave 3I/ATLAS the non-periodic comet designation C/2025 N1 (ATLAS).[2] By the time 3I/ATLAS was announced, the MPC had collected 122 observations of the comet from 31 different observatories.[2]
(From Wikipedia.)
I answered that two posts prior. Yes, we do know. The asteroid belt was never a single object.
Possible, but highly unlikely. More relevantly, the reverse can also happen: Interactions with a planet could cause an object that was previously bound to our solar system to be ejected. This is probably the origin of some of these interstellar objects. It happens very, very rarely in an old, mature system like ours, because almost anything in an orbit such that it could be ejected already has been, but it was probably fairly common when the solar system was new.
I would say that is the origin of all interstellar objects.
From the Wikipedia article I referenced earlier:
Current models of Oort cloud formation predict that more comets are ejected into interstellar space than are retained in the Oort cloud, with estimates varying from 3 to 100 times as many.[2] Other simulations suggest that 90–99% of comets are ejected.[17]