From what I could understand the speed of 45 km/sec was one of the characteristics that lead to the conclusion that CNEOS 2014 is extra solar. I assume the object had to be tracked by NORAD in 2014? But why couldn't it have origined from an impact ejection right in our solar system?

If a meteor hits an object in our solar system with sufficient impact couldn't that have accelerated the fragments to 45 km/sec?

If true that is pretty remarkable detective work not to mention luck that we found one after so many years of radar searching. ( Not that anyone was actually looking for it, I imagine they are constantly looking for nukes. )

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    $\begingroup$ Do you mean CNEOS 2014-01-08 (Siraj and Loeb 2019)? $\endgroup$
    – Mike G
    Aug 31, 2023 at 2:56
  • $\begingroup$ I added a / the link. Please revise, if Mike's and my guess is wrong $\endgroup$ Aug 31, 2023 at 5:43
  • $\begingroup$ I was reading in the press and you may be spot on. I am sorry for the confusion I caused. I should have included the link to the original article that I was referring to. However the question I see has been addressed below and is very interesting. The jury is still out on this mystery but I am still somewhat skeptical that it is an object from outside the solar system. This would truely be remarkable in my opinion. $\endgroup$
    – Sedumjoy
    Aug 31, 2023 at 14:29
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    $\begingroup$ @Sedumjoy You left out the word 'from" in your title, making it confusing. $\endgroup$ Aug 31, 2023 at 15:13
  • $\begingroup$ ...thank you I fixed it! $\endgroup$
    – Sedumjoy
    Aug 31, 2023 at 18:46

1 Answer 1


Short answer

By tracing back from the known position and velocity of the object before it entered the Earth's atmosphere, the claim is that is was never in the vicinity of any major Solar System objects and so its very high speed (higher than the escape speed of the Solar System) suggests it came from outside the Solar System.


I'm not sure the Department of Defense did the analysis that suggested the objects was from outside the Solar System. Instead, I think it was Siraj & Loeb (2022) (actually, first presented as a preprint on arXiv in 2019) who did the analysis.

It is the final, published version of the paper that makes reference to a US defense department letter, that was issued after Siraj & Loeb made their initial claim in 2019. At least that's what is said in the published paper. That letter is addressing whether the velocity of the meteor was known precisely enough to claim an interstellar origin, since the details of the measurements and uncertainties are classified.

The published paper then goes on to do an N-body analysis within the Solar System, tracing back the trajectory of the meteor based on its position and velocity just above the atmosphere. The authors conclude

There are no substantial gravitational interactions between the meteor and any planet other than Earth for any trajectory within the reported errors.

So that is the answer to your question - the meteor does not trace back to any other Solar System body that is significant enough in size to generate the speed observed. The very high speed (higher than the escape speed from the Solar System at the position of the Earth) then suggests it entered the Solar System from elsewhere. The authors do not specifically exclude that the object could have perhaps arisen from the collision of two objects in the outer Solar System.

The status of this object isn't settled though. It was picked out by Siraj & Loeb as having a high speed from a large catalogue. There is therefore some probability that it is simply an outlier caused by uncertainties. A paper by Brown & Borovicka (2023) makes a comparison of meteors jointly detected by the US government network and independent observers. They claim that the US government overestimates the speeds of faster meteors and that the most likely explanation of this particular event is that it really had a lower speed and has an origin from within the Solar System.

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    $\begingroup$ Thank you for this excellent detail. Answer accepted. I will be watching what the outcome of the analysis of the fragments are but must admit I am somewhat skeptical that an object from outside the solar system was found. $\endgroup$
    – Sedumjoy
    Aug 31, 2023 at 14:42

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