tähtiluokitus

tähtiluokitus is a Finnish term that can refer to two distinct systems that use stars as a unit or symbol. In everyday language it commonly designates star ratings for services and accommodations, while in astronomy it denotes stellar classification by physical properties such as temperature and luminosity.

Star ratings in consumer services are used to communicate quality to customers. Scales typically run from one to five stars, with higher ratings signaling better overall quality. Ratings are awarded by national tourism authorities, accreditation bodies, or independent inspectors based on published criteria such as facilities, cleanliness, service, safety, and accessibility. Standards vary by country and sector.

Ratings may be revised after renovations or periodically. They can influence pricing, marketing, and consumer trust, and may be suspended if standards are not met.

European practice shows variation, with schemes often national rather than EU-wide. Local authorities or private agencies generally determine star counts.

In astronomy, tähtiluokitus denotes the system that classifies stars by temperature and luminosity. The standard spectral sequence runs from hottest to coolest as O, B, A, F, G, K, M, with numeric subdivisions. A separate luminosity system uses classes I to V to distinguish giants and dwarfs. Modern classification relies on spectroscopy and photometry to assign a precise type, with extensions for very hot or cool objects.

Both usages encode qualitative information into standardized categories that aid comparison and study.