This is very cool. Along with a visible supernova and a super bright comet, this is one of those things I dreamed about as an astronomy nerd kid.
Though part of me wants to say "Pictures or it didn't happen!"
Caltech Researchers Find Evidence of a Planet Beyond Pluto
91–100 of 159 posts
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#92Earlier quoted context omitted.
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.)
If you're just trying to see all the objects, then yes, N^4. But if you're trying to figure out whether they're planets, you need to either resolve disks or take multiple observations to observe motion. I don't have a good feel for how the latter scales with N in practice...
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#93The 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
#94Earlier quoted context omitted.
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…
rate of occurrence is the same as certainty when it comes to p values, isn't it? At least 6.9 million hits use both phrases - https://www.google.com/search?q=p+values+certainty+%22rate+o...
The top one might be interesting here.
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#95I've been seeing news stories about Planet X for far too long to take any of this seriously, no matter how seemingly trustworthy the news source is.
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#96The biggest casualty of Science this decade has been elementary school dioramas.
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#97they can photograph distant galaxies, but they can't be sure how many planets there actually are on our solar system. weird.
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#98> 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…
> 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.
Please don't spread FUD about other people's research and then try to soften it with a disclaimer about how you're "in no position to determine" anything about the research.
If you want to offer criticism of the research, you should do the legwork to find out what the researchers did and did not do.
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#99Does it mean Voyager hasn't really escaped Sun's influence yet?
Voyager won't escape the Sun's influence for hundreds of years. The "boundary of the solar system" is not the same as the Sun's influence (and, indeed, is somewhat poorly defined, given how many times Voyager has crossed it.)
Re: Caltech Researchers Find Evidence of a Planet Beyond Pluto
#100If 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…
The criteria for clearing an orbit are apparently somewhat involved[1]. It can't just be a matter of no other bodies having the same distance from the sun or Pluto would disqualify Neptune and Jupiter would be disqualified by its trojans. Because the planets in these cases mass so much more than other other nearby bodies those other bodies dance to the planet's tune and aren't counted against the planet in terms of c…
I was misremembering Pluto's mass as being 1/10 of Earth's when it's really 1/500th. It would take a large number of TNOs to push this hypothetical object from being a planet to being a dwarf planet.