Learn Hardcore Russian: Новое открытие радует меня.

Because открытие is a neuter noun in the nominative case. Adjectives in Russian must agree with the noun they modify in gender, number, and case. The neuter singular nominative form of новый is новое, so we say новое открытие.

What case is открытие in, and how do you know?

Открытие is in the nominative case because it functions as the subject of the sentence—it is “what” performs the action (it pleases). In Russian, the subject of a clause is normally in the nominative.

What does the verb радует mean, and why is it used here?

Радует is the 3rd person singular present form of радовать, which literally means “to make someone happy” or “to please.” The sentence literally reads “The new discovery pleases me.” It’s a transitive verb taking a direct object (the person who is pleased).

Why is меня used instead of мне in this sentence?

Меня is the accusative case form of я, used after verbs like радовать that take a direct object in the accusative. Although меня looks identical to the genitive, here it is functioning as the accusative object.

Could I say Меня радует новое открытие? Would that change the meaning?

Yes, you can. Russian has relatively free word order due to its case system. Меня радует новое открытие still means “The new discovery pleases me,” but it places extra emphasis on меня (on “me”).

How would you express “I am happy about the new discovery” in a first-person way?

Use the intransitive/reflexive verb радоваться and the dative case: Я радуюсь новому открытию. Here новому открытию is dative, because радоваться takes a dative object.

What is the difference between радовать and радоваться?

Радовать (without –ся) is transitive: “to make someone happy,” and it takes an accusative object (e.g., радует меня).
Радоваться (with –ся) is intransitive/reflexive: “to be happy about” or “to rejoice,” and it takes a dative object (e.g., радуюсь чуду, “I rejoice at the wonder”).

Where is the stress in открытие and радует?

открытие: stress on the second syllable – открЫтие
радует: stress on the first syllable – РÁдует