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No one's mentioned Tyche yet? https://en.wikipedia.org/wiki/Tyche_%28hypothetical_planet%29 https://en.wikipedia.org/wiki/Tyche_%28hypothetical_planet%2... In

No one's mentioned Tyche yet? https://en.wikipedia.org/wiki/Tyche_%28hypothetical_planet%29 https://en.wikipedia.org/wiki/Tyche_%28hypothetical_planet%2... In searching for Tyche, the WISE missions ruled out the possibility of anything larger than Saturn (95x the mass of Earth) out to about 10000 AU and anything larger than Jupiter (317x the mass of Earth) out to about 26000 AU. WISE was able to detect objects the size of Neptune (17x the mass of Earth) out to about 700 AU, so it should be possible to find the object proposed by the Caltech astronomers here (10x the mass of Earth at around 600 AU). I don't know if WISE's current condition would allow it to perform such a search, as it's completely out of coolant.

avz 11y ago
For comparison: * the aphelion of Sedna, the most distant dwarf planet of our Solar system is at 937 AU from the Sun [1], * distance between Proxima Centauri and the binary Alpha Centauri is 15,000 ± 700 AU [2], * one light year is 63,241.1 AU, * distance to the nearest star (Proxima Centauri [2]) is 4.2421 ly = 268,274.973 AU, [1] https://en.wikipedia.org/wiki/90377_Sedna https://en.wikipedia.org/wiki/90377_Sedna [2] https://en.wikipedia.org/wiki/Proxima_Centauri https://en.wikipedia.org/wiki/Proxima_Centauri EDIT: formatting and added Proxima-Alpha Centauri distance.
mutagen 11y ago
Their site at http://www.findplanetnine.com/p/blog-page.html http://www.findplanetnine.com/p/blog-page.html addresses the areas the Tyche survey and other surveys cover. My TLDR: * The WISE survey might only find Planet X at it's nearest approach. Kevin Luhman has redone the survey using the most sensitive WISE bands that only cover a narrow area of the sky and hasn't found Planet X. * They reviewed the Catalina Sky Survey and eliminated most of the areas they'd expect Planet X. * The Pan STARRS site survey didn't find Planet X. Conclusion: Planet X is at aphelion, difficult to find with the Milky Way as a (stunning) backdrop. I just found their paper: http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22 http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22 I wonder how their conclusions match with David Nesvorny's paper predicting a 5th planet having been ejected from the Solar System: http://arxiv.org/pdf/1109.2949v1.pdf http://arxiv.org/pdf/1109.2949v1.pdf
- rplnt 11y ago
  > Planet X is at aphelion, difficult to find with the Milky Way as a (stunning) backdrop. I would have assumed that planets are easier to detect when they have a backdrop? That the light can be blocked, partially blocked, bent, .. Isn't that the case?
  - static_noise 11y ago
    I'm not sure if you're referring to the tansit technique where a planet passes in front of a star multiple times which allows to determine the size and distance from the detectable dips in brightness. This technique wouldn't work well with a backdrop since it never passes in front of the same star twice. I'm also not sure if we can resolve the planet optically i.e. 1) it will always be smaller than a pixel of the telescope sensor 2) the pixels of the telescope sensor always collect light from the backdrop even if the planet is dead center on the group of pixels. When you detect the light of a planet without backdrop both problems would be much smaller because then you can actually see some tiny dark blurry object moving relative to the stars around it in the image.
  - xenophonf 11y ago
    You're thinking about one of the ways extrasolar planets can be detected, when they cross in front of their parent star (transit photometry) or when they're imaged using light magnified or redirected by a massive foreground object (gravitational microlensing). I don't think we have the capability to detect something in this solar system eclipsing a background object (whether that's a star or a galaxy or whatever else is out there).
    - versteegen 11y ago
      Correction, rogue planets are detected when their gravity causes micolensing of distant objects (stars), not the other way around. https://en.wikipedia.org/wiki/Rogue_planet#Observation https://en.wikipedia.org/wiki/Rogue_planet#Observation Not an astronomer, but my impression is that microlensing couldn't be used to detect objects in our own solar system, but I don't see any reason why eclipsing of distant stars couldn't be used... it would be far too rare to be practical to find a planet, though.

avz 11y ago

For comparison: * the aphelion of Sedna, the most distant dwarf planet of our Solar system is at 937 AU from the Sun [1], * distance between Proxima Centauri and the binary Alpha Centauri is 15,000 ± 700 AU [2], * one light year is 63,241.1 AU, * distance to the nearest star (Proxima Centauri [2]) is 4.2421 ly = 268,274.973 AU, [1] https://en.wikipedia.org/wiki/90377_Sedna https://en.wikipedia.org/wiki/90377_Sedna [2] https://en.wikipedia.org/wiki/Proxima_Centauri https://en.wikipedia.org/wiki/Proxima_Centauri EDIT: formatting and added Proxima-Alpha Centauri distance.

mutagen 11y ago

Their site at http://www.findplanetnine.com/p/blog-page.html http://www.findplanetnine.com/p/blog-page.html addresses the areas the Tyche survey and other surveys cover. My TLDR: * The WISE survey might only find Planet X at it's nearest approach. Kevin Luhman has redone the survey using the most sensitive WISE bands that only cover a narrow area of the sky and hasn't found Planet X. * They reviewed the Catalina Sky Survey and eliminated most of the areas they'd expect Planet X. * The Pan STARRS site survey didn't find Planet X. Conclusion: Planet X is at aphelion, difficult to find with the Milky Way as a (stunning) backdrop. I just found their paper: http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22 http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22 I wonder how their conclusions match with David Nesvorny's paper predicting a 5th planet having been ejected from the Solar System: http://arxiv.org/pdf/1109.2949v1.pdf http://arxiv.org/pdf/1109.2949v1.pdf

rplnt 11y ago
> Planet X is at aphelion, difficult to find with the Milky Way as a (stunning) backdrop. I would have assumed that planets are easier to detect when they have a backdrop? That the light can be blocked, partially blocked, bent, .. Isn't that the case?
- static_noise 11y ago
  I'm not sure if you're referring to the tansit technique where a planet passes in front of a star multiple times which allows to determine the size and distance from the detectable dips in brightness. This technique wouldn't work well with a backdrop since it never passes in front of the same star twice. I'm also not sure if we can resolve the planet optically i.e. 1) it will always be smaller than a pixel of the telescope sensor 2) the pixels of the telescope sensor always collect light from the backdrop even if the planet is dead center on the group of pixels. When you detect the light of a planet without backdrop both problems would be much smaller because then you can actually see some tiny dark blurry object moving relative to the stars around it in the image.
- xenophonf 11y ago
  You're thinking about one of the ways extrasolar planets can be detected, when they cross in front of their parent star (transit photometry) or when they're imaged using light magnified or redirected by a massive foreground object (gravitational microlensing). I don't think we have the capability to detect something in this solar system eclipsing a background object (whether that's a star or a galaxy or whatever else is out there).
  - versteegen 11y ago
    Correction, rogue planets are detected when their gravity causes micolensing of distant objects (stars), not the other way around. https://en.wikipedia.org/wiki/Rogue_planet#Observation https://en.wikipedia.org/wiki/Rogue_planet#Observation Not an astronomer, but my impression is that microlensing couldn't be used to detect objects in our own solar system, but I don't see any reason why eclipsing of distant stars couldn't be used... it would be far too rare to be practical to find a planet, though.