ddahlen

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.

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.

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.

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

I posted a couple of months ago:

https://github.com/dahlend/kete

Research grade orbit calculations for asteroids and comets (rust/python).

I began working on this when I worked at caltech on the Near Earth Object Surveyor telescope project. It was originally designed to predict the location of asteroids in images. I have moved to germany for a PhD. I am actively extending this code for my phd research (comet dust dynamics).

Its made to compute the entire asteroid catalog at once on a laptop. There is always a tradeoff between accuracy and speed, this is tuned to be <10km over a decade for basically the entire catalog, but giving up that small amount of accuracy gained a lot of speed.

Example, here is the close approach of Apophis in 2029:

https://dahlend.github.io/kete/auto_examples/plot_close_appr...

As I said, just an order of magnitude estimate for many non-adaptive optics telescopes.

The atmosphere is always an issue, we can correct for many of the effects using adaptive optics, but there are always limits. The advantage you get from going bigger on the ground is that you are making a bigger "bucket" to put photons in. More photons = fainter objects are visible, this is the motivation for projects like:

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

Typically for non-adaptive optics telescope the atmosphere will limit you to the scale of about an arcsecond. Meaning objects which take up less than an arcsecond of the sky will appear as points. Adaptive optics telescopes however have much better resolving power.

I have been working in astronomy for a few years now and I recently have gone back to school for a PhD in orbital dynamics.

Rubin is going to make a big difference in our knowledge of the asteroid belt, it will likely more than triple the size of our known catalog of asteroids. Its actually somewhat difficult to know exactly how much it will increase our knowledge. The bigger the telescope we build, the fainter the asteroids we see. The difficulty is that while we can make a pretty educated guess as to how many smaller ones there are, this is such a jump that the error bars on that guess is quite large. I am quite excited to see how the catalog of asteroids changes, I expect we will be finding a LOT of smaller rocks near the Earth.

Asteroids have a broad range of albedo, basically the brightness of the surface can vary from the blackest coal (like 3-5% of the light reflecting) to concrete (up to about 50%). All visible range telescopes will be susceptible to a bias in their observations, since a big black rock will be as bright as a smaller paler rock. We know that the asteroid belt favors the dark material.

In a couple of years, the Near Earth Object Surveyor (NEOS) space telescope will launch. NEOS is an IR telescope and will not have the same albedo bias. The trade off is that it will measure the black body radiation, meaning asteroids have to be nearer the sun. Broadly these are very complementary surveys, Rubin will be fantastic for filling out the main belt, and NEO Surveyor will do a great job on our neighborhood.

Source: I worked at Caltech on NEOS, I wrote the code they use to predict known asteroid orbits:

https://github.com/dahlend/kete

Edit: I failed to mention that Rubin is a big deal for a lot of time-domain astronomy, I'm just being selfish talking about asteroids only.

I got a bit too excited with this one, this is may not be a full on dwarf planet, but it is a very large object. There are only a small number (about 10-20) objects in our solar system of this size. Its the first big one we have found in a number of years.

If you want to view the orbit:

https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2017%...

Depends on the albedo, if the H magnitude is a good measurement, then it is probably between 300-700km. These are rough bounds, its highly dependent on how reflective it's surface is (albedo).

With an orbit somewhere around 28k years, it reached perihelion in about 1931, at 45 au from the Sun.

The minor planet center is the clearing house of observations of objects in our solar system. They have announced a new dwarf planet today.

This object appears to be in a very eccentric orbit (0.948), and with an H magnitude of 3.55, so it is likely hundreds of km in diameter. Ceres for reference has a H magnitude of 3.33 (smaller H is bigger diameter).

If you want to know what H means: https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_Syste...

I have been in and out of the academic world my entire career. I have worked as a programmer/engineer for two universities and a national lab, and worked at a startup founded by some professors. There is huge uncertainty with the people whom I have worked with, nobody seems to be sure what is going to happen, but it feels like it wont be good. Hiring freezes, international graduate students receiving emails to self deport, and at my last institute many people's funding now no longer supports travel for attend conferences (a key part of science!).

One of the interesting pieces of science that I think a lot of people don't think about is strategic investment. At one point I was paid from a government grant to do high power laser research. Of course there were goals for the grant, but the grant was specifically funded so that the US didn't lose the knowledge of HOW to build lasers. The optics field for example is small, and there are not that many professors. It is an old field, most of the real research is in the private industry. However what happens if a company goes out of business? If we don't have public institutions with the knowledge to train new generations then information can and will be lost.

Basically all observations of solar system objects besides the big planets are going to be unresolved point sources. IE: We don't have telescopes which can resolve most objects into an image. An example, Hubble famously had to image a ton to get a grainy, ~12 pixel approximation of Pluto. We can do a lot with measurements of points, even reconstruct 3d models if we have enough data.

Resolving power is related to the PSF (Point Spread Function) size. The PSF is the image on your detector if you have an infinitely small point source. A quick google search says that DECam has a PSF of at least an arcsecond (atmosphere is probably causing issues for that). Which means anything smaller than an arcsecond is going to be unresolvable.

However, you still want pixels smaller than your PSF, since PSFs are typically gaussian-ish, having a bunch of measurements within the gaussian allows you to estimate the center accurately. This is vital for Astrometry (the measurement of position).

2 big reasons, first is that wobbles which we normally observe require that the star move enough to be detected on a shorter time scale. IE: if the orbit takes 100 years and we look twice in 5 years, the planet will have only moved 5% of an orbit and the wobble will be near 0. Second is the less mass and further the planet is away, the less noticeable the wobble. Something at 500 au is going to produce no measurable wobble in our lifetime.

Most images are registered by finding the location of known stars from a high resolution catalog such as GAIA. So you fit centroids of all stars in an image, then do a search of Gaia sources in that location and do some sort of linear or higher order polynomial mapping of pixel space to the celestial sphere reference coordinates ICRF.

Astrometry.net is a service that does an approximate version of this on the web.

I am glossing over many details here, but this is roughly what happens.

Thank you for the offer! Unfortunately the PhD has already sunk its claws in. I should have some flashy stuff to show off in a 2-3 months (I have a conference talk coming I have to prepare material for).

I've never really dabbled in youtube. I have several projects/papers I am working on using this code, I have thought about writing some blog posts as I publish those. But a PhD is going to be a major time sink, we will see what happens.

I am about to begin a PhD in astronomy. Until last month I was working at Caltech for 3 years on code which calculates orbits of asteroids to high precision. This code is being used on several NASA telescopes now to predict when they will image known asteroids (NEO Surveyor, SphereX, maybe Roman eventually). I was allowed to open source it and I am planning on making it the basis of my PhD research:

https://github.com/dahlend/kete

It can predict the location of the entire catalog of known asteroids to generally within the uncertainty of our knowledge of the orbits. Its core is written in rust, with a python frontend.

I cannot speak for the community, I don't have a very broad contact list for this sort of thing. Among the few people I know this has definitely drummed up some interest though (there are not nearly as many people who study asteroids as the public would think). Where JWST points is a complicated process that I only have a vague understanding of, this would likely require some kind of director discretionary time (I dont even know if JWST does that).

Wikipedia's source is: https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20Y...

It is currently moving away from us as it does its little dance around the sun. It will likely soon be too faint to see going forward until sometime in mid to late 2029, when we will likely see it again with NEO Surveyor, and likely the Vera Rubin LSST telescopes. It will spend most of that time with an apparent magnitude of probably fainter than 29. Once we spot it again in 2028/2029 time frame then there is a very high likely-hood that we will know its orbit well enough to know if it will miss or not (again, low, but not zero chance of impact).

You can view the current best fit orbit here: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...

Source: I write asteroid orbit calculation code for my day job. What I say here is unrelated to my employers, and should not in any way be construed as any official statement.

yeah it has corrections for GR of sun/jupiter/earth, along with J2 terms for those, and the 5 most massive asteroids.

Typically matches JPL Horizons results to sub 100km over a decade for vast majority of objects.

Optionally accepts non-grav forces as well.

I work on asteroid/comet orbit calculations for my day job. I had not actually seen this paper before, though I have done some detective work in old Palomar images in the past: https://caltech-ipac.github.io/kete/tutorials/palomar.html

I spent a few minutes and downloaded the image frame they cite in the paper and ran it through a similar analysis looking for known asteroids, and there were no known asteroids in that patch of sky at that time (didn't really expect any, as I would expect them to be causing a visible streak over the 10 minutes of exposure). Neat paper though!

I can tell you how I do it, but again I am not an impact study person. It helps to understand a bit of the background of how we fit orbits in general:

1) someone with a telescope sees something moving (typically these days these are bigger surveys)

2) These observations are submitted to the Minor Plant Center (MPC), the clearinghouse of all asteroid/comet observations.

3) Several groups pull observations from the MPC to fit orbits, including JPL Horizons (MPC also fits orbits)

4) You now have a pile of observations which you have to figure out which observation links to other observations, which is a complex math problem on its own. Solve that.

5) JPL Horizons for example then fits the orbits to the observations, and since the observations may be 100 years of data of wildly varying quality, from hand written notes in the 1920s through to modern data, this is very difficult. They publish a covariance matrix with the associated fit (IE: basically a gaussian error fit for the parameters).

6) I grab that covariance matrix and sample from it using some pretty vanilla statistics to build orbits.

7) Propagate and see what happens.

Here is an example of an observation from 1950: https://caltech-ipac.github.io/kete/tutorials/palomar.html The image was developed on a glass plate, this one was never even sent in to the MPC, the guy taking the observation just wrote down "Asteroid" on the cover slip for the image. It was not formally discovered until the 1980s. We now know its orbit very well, so this particular observation is not that interesting other than as a curiosity.

Here is an example of an orbit fit by JPL Horizons: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=c%2F2...

Note the "condition code" on the right, which is a score of how good their orbit fit matches the data, 0 means we know the orbit with high precision. This one is an 8, meaning we have a fit, but its not that great. Most likely because we only have 31 days of observations.

It's a bit of both, observing has uncertainty in a lot of places, if you are on the ground you get atmospheric effects, imprecision of timing, imprecision of optics, etc etc. You are also observing an object where you dont know how far away it is. That distance has to be solved by basically doing a sort of triangulation, which requires either the observer or the object to move enough. So if you observe over a short time (hours for example), you can see it is moving, but it is hard to tell distance.

Once you have an estimated orbit, if it has any interactions with planets (IE: flyby of Earth), small differences in positions during the close encounter make LARGE differences decades later. Add to this the effects of photons from the sun pushing on the smaller asteroids or dust, or out-gassing /dust from comets cause these objects to slightly drift from just the basic gravitational forces. Generally inner solar system asteroids (inside mars) are very chaotic over hundreds of years, though typically predictable less than a century.

Note that I am not an expert on impact calculations, I just know a bit about and and can do back of the envelope ones. There are a number of ways to get to the ~1%, the orbit fits have uncertainties on them and those can be propagated forward in time. However there are all sorts of complexities with doing that, and often the easiest method is to sample the uncertainty region a few hundred thousand times (Monte-carlo), and propagate those and see what hits.

I work on the Near Earth Object Surveyor space telescope (NEO Surveyor) writing simulation code which predicts which objects we will see. This one has drummed up a bit of interest due to its (relatively) high chance of impact. I actually spent quite a bit of time yesterday digging through archive images trying trying to see if it was spotted on some previous times it came by the Earth (no luck unfortunately). Since we saw it so briefly, our knowledge of its orbit is not that great, and running the clock back to 2016 for example ended up with a large chunk of sky where it could have been, and it is quite small. We will almost certainly see it again with NEO Surveyor years before its 2032 close encounter. I have not run a simulation for it, but I would not be surprised if LSST (a large ground telescope survey which is currently coming online) to catch it around the same time NEO Surveyor does.

Our knowledge of the diameter of this object is a bit fuzzy, because of surface reflectivity, small shiny things can appear as bright as dark large things. This is one of the motivations of making the NEO Surveyor an IR telescope, since IR we see black body emission off of the objects, which is mostly size dependent, and only weakly albedo dependent.

There is an even tinier chance that if it misses the Earth in 2032, it could hit the moon. I haven't run the numbers precisely for that one, but it impacted a few times in some monte-carlo simulations.

If anyone is interested in orbit dynamics, I have open sourced some of the engine we are using for observation predictions: https://github.com/Caltech-IPAC/kete

It is relatively high precision, though JPL Horizons has more accurate gravitational models and is far better suited for impact studies. My code is primarily for predicting when objects will be seen in telescopes.

I have recently managed to open source some of our tools which we use on the NEO Surveyor mission to simulate all of the asteroids. However my code lacks any real sort of visualizations:

https://github.com/Caltech-IPAC/kete

(note that installation is about 100mb, as it carries a large data file containing high accuracy positions of the planets for +- 100 years)

There are sort of two major camps in the field, the astronomers and the people who fly satellites. Having the thing you are measuring able to talk to you and get doppler measurements of its velocity is invaluable for orbit determination, so the modern techniques for the satellite group have probably continued to advance. Unfortunately on my side of the fence, rocks usually dont talk back and we have less information available for fitting. For a vast majority of the time all we get for asteroids are visible observations, which is very limited geometric information. The algorithms here have not advanced a whole lot for a looong time, Gauss famously developed the first optimization technique to find Ceres. The field still regularly uses "Gauss's Method" for orbit determination. There have been a few small improvements to numerical integrators, but the field as a whole tends to use the "tried and true" methods of the past. I had to go on ebay and get a bunch of texts from the 60s-80s as they are often the best, even now. The field is very very tiny, think maybe dozens to hundreds in the whole world.

We have spotted a grand total of 2 interstellar objects, they were moving faster, but are many orders of magnitude less numerous then the local stuff.

Just doing some back of the envelope calculations, looks like Omuamua was moving about 165,000km/hr (relative to Earth) when it was about at Earths orbital distance.

This speed is not actually a crazy number, it is a lot faster than the majority of things which could hit us, but there are geometries of things in our solar system which can reach these relative velocities. (For example things in retrograde, IE: reverse orbits) can lead to basically escape velocity + earths velocity.

We got enough data to get a rough estimate of its orbit before it hit: https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...

Note though, this will likely have a huge range of uncertainty on it, as 8 hours of observation is not a lot.