Live data from Hacker News

Caltech Researchers Find Evidence of a Planet Beyond Pluto

caltech.edu

31–40 of 159 posts

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#32
This is pretty solid science, even if, as others have pointed out, there's a bit of academic drama-rama and green jellybean stuff going on. In particular, their model made a prediction that they didn't set out looking for, which corresponded to existing observations. And of course, the whole hypothesis is easily testable. While they don't know where the hypothetical planet might be on it's orbit, it sounds like there's a good shot that small telescopes should be able to spot it.

Exciting stuff.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#33
post #7

Provocative title for this Caltech press release. Mike Brown, the co-author of the paper reported here, discovered Eris, a KBO like Pluto, in 2005. This discovery prompted the IAU in 2006 to demote Pluto out of the realm of "planet" into a "dwarf planet". At the time, Alan Stern's New Horizons mission to Pluto had just been launched, it finally arrived last year. Stern was incensed that NH started out as a visitor to…

Small nitpick: "largest" refers to mean radius, "massive" refers to mass (aka weight). Pluto is the second most massive, but it is the largest. (To be fair, it is a very close call: its diameter is only ~25km larger than Eris)

I'm excited to see this story unfold, if nothing else because it's fun looking up the mythological[1][2][3] origins of the names given to new celestial bodies :)

[1](https://en.wikipedia.org/wiki/Makemake)

[2](https://en.wikipedia.org/wiki/90377_Sedna)

[3](https://en.wikipedia.org/wiki/Haumea)

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#35
post #29

Did anyone else notice that the rendering of the orbits in the article looks strikingly similar to Kerbal Space Program's orbit UI?

Or is it perhaps the other way around. Did Kerbel use the same UI as a popular rendering program used by astronomers.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#36

> Batygin and Brown inferred its presence from the peculiar clustering of six previously known objects that orbit beyond Neptune. This raised a big red flag in my mind. This must produce a literally astronomical multiple comparisons problem. Yes they reported sigma = 3.8, but if they didn't do their multiple comparisons correction right (which I am in no position to determine), they're basically reading tea leaves. I…

I think you're right that that's one of the chief concerns, but I think you paint it incorrectly as a technical problem. ("Multiple comparisons" as you call it. Particle physicists call it the "look-elsewhere effect": https://en.wikipedia.org/wiki/Look-elsewhere_effect )

The easy, though tedious, part of the look-elsewhere effect is to calculate a probabilisitic correction for all the various combinatorics of X objects in Y orbits over a time period of length Z that one might have seen. The hard, and borderline philosophical, part is to identify the proper reference class, i.e., what qualitatively different sorts of observations might have also considered evidence for planet nine, and how many other astrophysical searches are we running that might have given us weird results? This is really where frequentist approaches strain to be useful, and it's hard to avoid resorting to a Bayesian prior.

Analogously for particle physics, it's easy to compute the chance of getting a 4-sigma deviation for two different experiments in any gamma-gamma energy bins, so the after-the-fact corrections to the significant of a fluctuation in a particular bin are easy to compute. Much more difficult is to consider all the hundreds of parallel searches going on, of greatly varying levels of motivation, and correcting based on that.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#37

> Batygin and Brown inferred its presence from the peculiar clustering of six previously known objects that orbit beyond Neptune. This raised a big red flag in my mind. This must produce a literally astronomical multiple comparisons problem. Yes they reported sigma = 3.8, but if they didn't do their multiple comparisons correction right (which I am in no position to determine), they're basically reading tea leaves. I…

Keep reading, their simulation explains several additional previously unrelated trajectories.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#39
post #31

https://en.wikipedia.org/wiki/Zecharia_Sitchin He believed this hypothetical planet of Nibiru to be in an elongated, elliptical orbit in the Earth's own Solar System, asserting that Sumerian mythology reflects this.

A broken clock is right twice a day.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#40
post #33
post #7

Provocative title for this Caltech press release. Mike Brown, the co-author of the paper reported here, discovered Eris, a KBO like Pluto, in 2005. This discovery prompted the IAU in 2006 to demote Pluto out of the realm of "planet" into a "dwarf planet". At the time, Alan Stern's New Horizons mission to Pluto had just been launched, it finally arrived last year. Stern was incensed that NH started out as a visitor to…

Small nitpick: "largest" refers to mean radius, "massive" refers to mass (aka weight). Pluto is the second most massive, but it is the largest. (To be fair, it is a very close call: its diameter is only ~25km larger than Eris) I'm excited to see this story unfold, if nothing else because it's fun looking up the mythological[1][2][3] origins of the names given to new celestial bodies :) [1]( https://en.wikipedia.org/w…

Mass isn't weight, it's the amount of matter. Weight is the measure of the pull of gravity on mass.
Post reply on HN