astronomiijaid is the plural accusative or plural genitive of astronomiija.

astronomiijaN

Finnish

astronomiaN; tähtitiedeN

Nordsamisk-finsk ordbokdict-sme-fin/src/n_smefin.xml:96931Edit on GitHub Suggest

astronomijjaN

North Sámi – Lule Sámidict-sme-smj/src/all_smesmj.xml:15887Edit on GitHub Suggest

Case	Sg	Pl
Nom	astronomiija	astronomiijat
Acc	astronomiija	astronomiijaid
Gen	astronomiija	astronomiijaid
Ill	astronomiijai / astronomiijii	astronomiijaide
Loc	astronomiijas	astronomiijain
Ess	astronomiijan
Com	astronomiijain	astronomiijaiguin