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ʻOumuamua passed its closest point at about 0.25 UA from the Sun.

Has anyone researched what the odds were that the first ever spotted interstellar object passed so close to the Sun?

Being the interstellar space almost totally empty, I would intuitively suppose that such odds would be extremely low.

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How could it be found otherwise? It is currently (November 2018) only at about the orbital distance of Mars and cannot be detected by the world's largest telescopes.

Such objects are small and only seen in reflected light - they have to get close to the Sun (and Earth) to be seen. There may well be a substantial population of interstellar rocks passing through the solar system unseen at greater distances.

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  • $\begingroup$ Fair point, but my question is about such a close perihelion. $\endgroup$ – kYuZz Nov 16 '18 at 17:05
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The odds are actually very good, for the simple fact that the object could be observed. If it was much further away than that, it could not be observed.

It's like eating a rare food, then asking yourself, what are the odds that that tasty morsel was ever so close to my mouth? Well, if you ate it already, the odds are actually 100%.

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