This is the 1065th most frequent Russian word.
планете
The Russian word "планете" translates to "planet" in English (dative or prepositional case).
In this sentence, 'планете' is the dative case of the noun 'планета' which means 'planet', used here to specify the location.
На нашей планете много различных животных.
On our planet, there are many different animals.
In this usage, 'планете' is also in the dative case and is used after the verb 'угрожать' which takes an object in the dative case.
Экологические проблемы угрожают планете.
Environmental problems threaten the planet.
Here, 'планете' is in the prepositional case of the noun 'планета', specifying the subject of discussion and location.