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Comment by gus_massa | Hacker News Reader

> hundreds of km

How big is that compared with other dwarf planets/ Moons? If you sort all dwarf planets by size, which position does this take (approximately)?

Pluto -> 2300 Km

Ceres -> 950 Km

Fobos(Mars) -> 25 Km

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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.

So it's roughly in the closest 200-year period out of 28,000 years. That means it spends 99.3% of it's orbit further away than now, and thus harder to find.

Simplistic odds would seem to imply that there's over a hundred more dwarf planets just like this but further away, so we just haven't seen them.

I really hope we can get some more sensitive and wider telescopes to look deeper into the Oort cloud. At those distances, sunlight is comparable to a full moon or less, surface temperatures are only tens of kelvin. And yet they're still less than 1% of the distance to the next star.

[I'm lost with all the recent discoveries.]

Assuming 500Km, is in in the top 10 by size/mass[1][2]? Top 100? Top 1000? Top 1000000?

[1] Yes I know it's not the same. Whatever criteria is easier to measure.

[2] I guess not top 10, but I have no idea about the current knowledge of the long tail. Fake Edit: I took a look at https://en.wikipedia.org/wiki/List_of_possible_dwarf_planets So between 20 and 30???

Your comment was the one that really made all of this sink in, thanks. Wow.

This thread is making me realize that The Expanse has me pronouncing planetoids in Belter.

Beltalowda!

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