Editing Planetary system (section)

===Classification===
Planetary system architectures may be partitioned into four classes based on how the mass of the planets is distributed around the [[host star]]:<ref>{{Cite journal |last1=Mishra |first1=Lokesh |last2=Alibert |first2=Yann |last3=Udry |first3=Stéphane |last4=Mordasini |first4=Christoph |date=2023-02-01 |title=Framework for the architecture of exoplanetary systems - I. Four classes of planetary system architecture |url=https://www.aanda.org/articles/aa/abs/2023/02/aa43751-22/aa43751-22.html |journal=Astronomy & Astrophysics |language=en |volume=670 |pages=A68 |doi=10.1051/0004-6361/202243751 |issn=0004-6361|doi-access=free |arxiv=2301.02374 |bibcode=2023A&A...670A..68M }}</ref><ref>{{Cite journal |last1=Mishra |first1=Lokesh |last2=Alibert |first2=Yann |last3=Udry |first3=Stéphane |last4=Mordasini |first4=Christoph |date=2023-02-01 |title=Framework for the architecture of exoplanetary systems - II. Nature versus nurture: Emergent formation pathways of architecture classes |url=https://www.aanda.org/articles/aa/abs/2023/02/aa44705-22/aa44705-22.html |journal=Astronomy & Astrophysics |language=en |volume=670 |pages=A69 |doi=10.1051/0004-6361/202244705 |issn=0004-6361|doi-access=free |arxiv=2301.02373 |bibcode=2023A&A...670A..69M }}</ref>

* '''Similar:''' The masses of all planets in a system are similar to each other. This architecture class is the most commonly-observed in our galaxy. Examples include [[TRAPPIST-1|Trappist-1]]. The planets in these systems are said to be like 'peas in a pod'.<ref name="peas">{{Cite journal |last1=Mishra |first1=Lokesh |last2=Alibert |first2=Yann |last3=Leleu |first3=Adrien |last4=Emsenhuber |first4=Alexandre |last5=Mordasini |first5=Christoph |last6=Burn |first6=Remo |last7=Udry |first7=Stéphane |last8=Benz |first8=Willy |date=2021-12-01 |title=The New Generation Planetary Population Synthesis (NGPPS) VI. Introducing KOBE: Kepler Observes Bern Exoplanets - Theoretical perspectives on the architecture of planetary systems: Peas in a pod |url=https://www.aanda.org/articles/aa/abs/2021/12/aa40761-21/aa40761-21.html |journal=Astronomy & Astrophysics |language=en |volume=656 |pages=A74 |doi=10.1051/0004-6361/202140761 |issn=0004-6361|doi-access=free |arxiv=2105.12745 |bibcode=2021A&A...656A..74M }}</ref>
* '''Mixed:''' The masses of planets in a system show large increasing or decreasing variations. Examples of such systems are [[Gliese 876]] and [[Kepler-89]].
* '''Anti-Ordered:''' The massive planets of a system are close to the star and smaller planets are further away from the star. There are currently no known examples of this architecture class.
* '''Ordered:''' The mass of the planets in a system tends to increase with increasing distance from the host star. The [[Solar System]], with small [[Terrestrial planet|rocky planets]] in the inner part and [[giant planet]]s in the outer part, is a type of Ordered system.