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Caltech Researchers Find Evidence of a Planet Beyond Pluto

caltech.edu

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Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#81

Post by sandworm101 »

asavadatti wrote: post #69
sandworm101 wrote: post #61

Earlier quoted context omitted.

If naming was all about logic then 1/2 the places on earth would need to be renamed. Naming is about emotion, style, history, and personal preference. Even total mistakes (the Giant Squid) are grandfathered through. Galileo named the moons of Jupiter after his sponsors. I just hope this thing doesn't become "X, brought to you by iPhone8".

I think you are confusing naming and classification.

Something can be called "Planet X" without being classified as a planet. Take "Planet Hollywood". Incorporating planet into the name should at least protect against future reclassification.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#83

Post by jerf »

jessriedel wrote: post #36
tdaltonc wrote: post #25

> 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 objec…

I'd also observe that in terms of prior probability, "There is a ninth planet in the solar system that we have not yet detected" is probably hovering at least in the low-integer percentages, and I imagine some scientists would place it higher than that. The general idea is not a wild, far-out one by any stretch of the imagination.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#85

Post by jessriedel »

bzbarsky wrote: post #75
logingone wrote: post #15

I don't seem to have a grasp of our visibility of our solar system. We can see a number of the planets with the naked eye, a number of the moons with binoculars and a few hundred $/£/€/.. telescope. Yet even with these great big radio telescopes, antenna arrays, Hubble, etc, we seem to be quite unaware of what's in our neighbourhood. Anyone have figures of how much we've surveyed?

It's all about distances. The planets we can see with the naked eye are at most 11AU from us (Saturn is at 10AU at aphelion). For comparison, Neptune is never closer than about 29AU to us. Brightness goes down as the square of the distance. But it gets worse, because that's brightness at given source brightness. Planets don't radiate intrinsically; they reflect sunlight. And sunlight brightness drops off as the squar…

Shouldn't it be fourth power of distance (N^4) not sixth? For objects beyond the diffraction limit (i.e., objects whose radius cant be resolved), visibility is determined by total light reaching the observer. Angular size isn't important. (And, if anything, diffusing a fixed amount of light over a larger solid angle makes it harder to see.)

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#87

Post by nkrisc »

logingone wrote: post #15

I don't seem to have a grasp of our visibility of our solar system. We can see a number of the planets with the naked eye, a number of the moons with binoculars and a few hundred $/£/€/.. telescope. Yet even with these great big radio telescopes, antenna arrays, Hubble, etc, we seem to be quite unaware of what's in our neighbourhood. Anyone have figures of how much we've surveyed?

Just to offer some context in layman's terms:

1. These objects are very, very far from the sun (and Earth).

2. These objects are planet(oids), not stars, so don't produce their own light.

3. They are probably very cold and don't emit much in the IR spectrum.

4. They may have low albedo, coupled with their distance from the sun, means they reflect very little visible light.

5. Space is huge. Trying to spot a tiny, dark, object many AU from Earth is no easy task if you don't know exactly where to look.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#88

Post by [deleted] »

logicallee wrote: post #54
tdaltonc wrote: post #25

> 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…

So I might not have a great enough understanding but isn't 3.8 sigma not high for this kind of announcement (with the current title)? if someone wants to report finding a planet in the solar system ten times the size of Earth wouldn't they do so at more than @3.8 sigma. In particular, the prior is quite low because it would affect a bunch of other astronomical calculations, wouldn't it? So you would want the confiden…

[deleted]

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#89

Post by peeters »

logicallee wrote: post #54
tdaltonc wrote: post #25

> 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…

So I might not have a great enough understanding but isn't 3.8 sigma not high for this kind of announcement (with the current title)? if someone wants to report finding a planet in the solar system ten times the size of Earth wouldn't they do so at more than @3.8 sigma. In particular, the prior is quite low because it would affect a bunch of other astronomical calculations, wouldn't it? So you would want the confiden…

I'm having trouble following your height example because "finding" is not well defined, and it's conflating rate of occurrence with certainty.

Being on a blind date with someone who is 6'8" is like knowing someone that won the lottery. The chance of winning the lottery is very low, but lots of people play it and chances are the winner has friends. You're unique, but have no reason to be incredulous.

This data being a coincidence is more on par with one person getting one chance to correctly predict (some of) tomorrow's lottery numbers. It's 1 in 13822.

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