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Caltech Researchers Find Evidence of a Planet Beyond Pluto

caltech.edu

41–50 of 159 posts

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#41
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.

Or, third option, "there's only a few decent ways to represent orbits on a graphic".

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#42
post #13

Earlier quoted context omitted.

They do, and at the end of the press release it says that Brown has begun an observing campaign to find the planet. Unfortunately detecting these very distant objects is very difficult. The light we see from them is reflected light from the Sun, so their apparent brightness goes as 1/r^4, not 1/r^2 like most objects. And because they are so close, there is a strong parallax from the motion of the Earth. THe consequen…

I would expect a smear with characteristics of the planet would be as effective to identify it as a single snapshot. Wouldn't the direction be well identified from indirect detection? Is the blur also less effective because of increased background exposure?

Well, if the smear takes the light level below the noise floor of the sensor then you can't even say that there's a smear.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#43

Why wouldn't their calculations be able to suggest possible locations for the planet?

They do, and at the end of the press release it says that Brown has begun an observing campaign to find the planet. Unfortunately detecting these very distant objects is very difficult. The light we see from them is reflected light from the Sun, so their apparent brightness goes as 1/r^4, not 1/r^2 like most objects. And because they are so close, there is a strong parallax from the motion of the Earth. THe consequen…

Are you sure it's r^4, not 4r^2?

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#44

> 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…

The anomaly itself does not seem to be disputed. It's true that when looking for arbitrary clusters and unusual patterns you can pretty much always find something -- though it's more of a Texas Sharpshooter fallacy [1] than the kind of multiple comparisons you see in e.g. medical research -- but the paper in question [2] mentions a whole bunch of alternative theories for why the particular clustering of a bunch of rocks in the Kuiper belt is what it is, and it doesn't seem very likely to me that none of those researchers ever thought "well, gee, maybe this is all just a fluke." In fact the competing hypotheses would be my main source of skepticism – maybe it's a planet, maybe it's an entirely different phenomenon.

[1] https://en.wikipedia.org/wiki/Texas_sharpshooter_fallacy

[2] http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22...

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#46
post #33

Earlier quoted context omitted.

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.

Sorry, you're right. I should've qualified that I meant the colloquial usage of the word "weight".

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#47
post #43

Earlier quoted context omitted.

They do, and at the end of the press release it says that Brown has begun an observing campaign to find the planet. Unfortunately detecting these very distant objects is very difficult. The light we see from them is reflected light from the Sun, so their apparent brightness goes as 1/r^4, not 1/r^2 like most objects. And because they are so close, there is a strong parallax from the motion of the Earth. THe consequen…

Are you sure it's r^4 , not 4r^2 ?

Yes. The solid angle subtended by the planet (and hence the amount of reflected light) goes as 1/r^2, and then the apparent brightness of the reflected light to us goes as an additional 1/r^2. The total dependence is then 1/r^2 * 1/r^2 = 1/r^4.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#48
The NY Times covers the story well:

http://www.nytimes.com/2016/01/21/science/space/ninth-planet...

EDIT: After reading the comments in this discussion, many of which are addressed in the NYT article, I'd say the NYT article is almost certainly worth reading.

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#49
post #12

If it holds up, this is fantastic. Given how interesting the Pluto system has turned out to be, I can only fantasise about a potential super-earth system relatively nearby. However, to be completely pedantic: would this actually be a planet ? Or still a dwarf planet , despite its massive size? Keep in mind that the definition of planethood is not only that it's large enough to be rounded by its own gravity, but that…

> would this actually be a planet? Or still a dwarf planet

The NY Times article covers this question in some detail, and says the experts are certain this would be a ninth planet:

http://www.nytimes.com/2016/01/21/science/space/ninth-planet...

Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto

#50

Giant, weird orbit, debate ... there can be only one name. This is Planet X. Also because X would be 10th discovered planet, a reference that pluto, while not a planet today, was indeed the ninth _discovered_ planet.

If you are going by that logic, Pluto was at least the 10th planet discovered and this is at least the 11th. Ceres was discovered before either Neptune or Pluto and spent 50 years as a "planet". It eventually went through a similar reclassification process as Pluto as other similar objects were discovered. The only reason you don't see the same controversy around its classification is because it was recategorized a century before any of us were born.
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