Wikipedia:WikiProject Solar System/Importance ratings

All pages belonging to the Solar System should be rated according to their importance. There four levels Top, High, Mid and Low.

1. Low importance is the default rating. It is assigned to any article which is of specialist interest, and where there are only few reliable sources about its subject.
2. Mid importance should be assigned to any article that meets the following two criteria: (a) there are sufficient reliable sources to write at least a B-class article; (b) the article is about a significant body or part of the Solar System, important event or space mission, notable planetary scientist, which is or likely to be of interest to the general public.
3. High importance should be assigned to any article that meets the following two criteria: (a) there are plenty of reliable sources to write at least a GA-class article; (b) the article is about a major body or part of the Solar System, very important event or space mission, famous planetary scientist, which is or likely to be of strong interest to the general public.
4. The top importance should be assigned to any article that meets criteria of high importance and, in addition, is either a core topic related to the Solar System or is an object, event or person that is widely known among the public and is subject to frequent discussions in non-scientific press.

The importance is not static. It evolves as new facts come to light, new events happen and new discoveries are made. The public perception of particular topics also changes with time.

WikiProject article importance scheme

Importance	Criteria	Example
Top	Subject is extremely important, even crucial, to its specific field. Reserved for subjects that have achieved international notability within their field.	Solar System Mars Moon Earth
High	Subject is extremely notable, but has not achieved international notability, or is only notable within a particular continent.	Ganymede (moon) New Horizons Galilean moons 90377 Sedna
Mid	Subject is only notable within its particular field or subject and has achieved notability in a particular place or area.	Comet Shoemaker–Levy 9 Asteroid Ariel (moon)
Low	Subject is not particularly notable or significant even within its field of study. It may only be included to cover a specific part of a notable article.	Deimos (moon) Coriolis (crater) Google Mars
NA	Subject importance is not applicable. Generally applies to non-article pages such as redirects, categories, templates, etc.	Category:Solar System
???	Subject importance has not yet been assessed.	United States Youth Council