planeta

/planeta/

Cases

SingularPluralWhen to use it
nominativeplanetathe planetplanetalathe planetsthe plain dictionary form — the doer of the sentence
genitiveplanetanıthe planet'splanetalanıthe planets'the owner — whose it is
accusativeplanetanıthe planet (as the object)planetalanıthe planets (as the object)a specific, known object — whom or what
dativeplanetağato the planetplanetalağato the planetsdirection or recipient — to where, to whom
locativeplanetadaat / in the planetplanetaladaat / in the planetswhere it is; also having — mende bar, "I have it"
ablativeplanetadanfrom the planetplanetaladanfrom the planetswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
myplanetammy planetplanetalarımmy planets
yourplanetangyour planetplanetalarıngyour planets
his / herplanetasıhis / her planetplanetalarıhis / her planets
ourplanetabızour planetplanetalarıbızour planets
you all'splanetağızyou all's planetplanetalarığızyou all's planets
theirplanetalarıtheir planetplanetalarıtheir planets

The overlap in the last rows is real, not a mistake: planetaları can mean "his / her planets", "their planet", or "their planets" — context decides.