Editing Planets beyond Neptune (section)

==Constraints on additional planets==
As of 2023 the following observations severely constrain the mass and distance of any possible additional Solar System planet:
* An analysis of mid-infrared observations with the [[Wide-field Infrared Survey Explorer|''WISE'' telescope]] have ruled out the possibility of a [[Saturn]]-sized object (95 Earth masses) out to 10,000 [[astronomical unit|AU]], and a Jupiter-sized or larger object out to 26,000 AU.<ref name="Luhman2014"/> ''WISE'' has continued to take more data since then, and NASA has invited the public to help search this data for evidence of planets beyond these limits, via the [[Backyard Worlds|Backyard Worlds: Planet 9]] citizen science project.<ref name="CNN-NASA-Search-Worlds">{{cite news|title=NASA wants you to help find a new planet|url=https://edition.cnn.com/2017/02/16/us/nasa-search-worlds-trnd/index.html|work=[[CNN]]|date=16 February 2017|access-date=11 March 2018}}</ref>
* Using modern data on the [[Anomalous perihelion precession|anomalous precession]] of the perihelia of Saturn, Earth, and Mars, Lorenzo Iorio concluded that any unknown planet with a mass of 0.7 times that of Earth must be farther than 350–400&nbsp;AU; one with a mass of 2 times that of Earth, farther than 496–570&nbsp;AU; and finally one with a mass of 15 times that of Earth, farther than 970–1,111&nbsp;AU.<ref name="Iorio2014">{{Cite journal |last=Iorio |first=L. |year=2014 |title=Planet X revamped after the discovery of the Sedna-like object 2012 VP113? |journal=Monthly Notices of the Royal Astronomical Society: Letters |language=en |volume=444 |issue=1 |pages=L78–L79 |arxiv=1404.0258 |bibcode=2014MNRAS.444L..78I |doi=10.1093/mnrasl/slu116 |issn=1745-3933 |s2cid=118554088 |doi-access=free}}</ref> Moreover, Iorio stated that the modern ephemerides of the Solar System outer planets has provided even tighter constraints: no celestial body with a mass of 15 times that of Earth can exist closer than 1,100–1,300&nbsp;AU.<ref name=Iorio2014-2>{{cite journal |arxiv=1407.5894|doi=10.3389/fspas.2017.00028|title=Is the Recently Proposed Mars-Sized Perturber at 65–80 AU Ruled Out by the Cassini Ranging Data?|journal=Frontiers in Astronomy and Space Sciences|volume=4|year=2017|last1=Iorio|first1=Lorenzo|page=28|bibcode=2017FrASS...4...28I|s2cid=26844167|doi-access=free}}</ref>  However, work by another group of astronomers using a more comprehensive model of the Solar System found that Iorio's conclusion was only partially correct. Their analysis of [[Cassini–Huygens|''Cassini'']] data on Saturn's orbital residuals found that observations were inconsistent with a planetary body with the orbit and mass similar to those of Batygin and Brown's Planet Nine having a [[true anomaly]] of −130° to −110°, or −65° to 85°. Furthermore, the analysis found that Saturn's orbit is slightly better explained if such a body is located at a true anomaly of {{val|117.8|+11|-10|u=deg}}. At this location, it would be approximately 630 AU from the Sun.<ref>{{cite journal |title=Constraints on the location of a possible 9th planet derived from the Cassini data |journal=[[Astronomy and Astrophysics]] |arxiv=1602.06116 |first1=A |last1=Fienga |first2=J |last2=Laskar |first3=H |last3=Manche |first4=M |last4=Gastineau |date=23 February 2016 |doi=10.1051/0004-6361/201628227 |volume=587 |page=L8 |bibcode=2016A&A...587L...8F|s2cid=119116589 }}</ref>
* Using public data on the orbits of the [[extreme trans-Neptunian object]]s, it has been confirmed that a statistically significant (62σ) asymmetry between the shortest mutual ascending and descending nodal distances does exist; in addition, multiple highly improbably (p < 0.0002) correlated pairs of orbits with mutual nodal distances as low as 0.2&nbsp;AU at 152&nbsp;AU from the Solar System's barycentre or 1.3&nbsp;AU at 339&nbsp;AU have been found.<ref name="de la Fuente Marcos">{{cite journal |last1=de la Fuente Marcos |first1=Carlos |last2=de la Fuente Marcos |first2=Raúl |title=Twisted extreme trans-Neptunian orbital parameter space: statistically significant asymmetries confirmed |journal=Monthly Notices of the Royal Astronomical Society Letters |url=https://academic.oup.com/mnrasl/article-abstract/512/1/L6/6524836 |volume=512 |issue=1 |pages=L6–L10 |arxiv=2202.01693 |bibcode=2022MNRAS.512L...6D |doi=10.1093/mnrasl/slac012 |date=1 May 2022|doi-access=free }}</ref> Both findings suggest that massive perturbers may exist at hundreds of AUs from the Sun and are difficult to explain within the context of a uniform distribution of orbital orientations in the outermost Solar System.<ref name="Napier_etal_2021">{{cite journal |last1=Napier |first1=J. K. |display-authors=etal |title=No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects |journal=The Planetary Science Journal |year=2021 |volume=2 |issue=2 |page=59 |doi=10.3847/PSJ/abe53e |arxiv=2102.05601|bibcode=2021PSJ.....2...59N |s2cid=231861808 |doi-access=free }}</ref>