Translation of "Serene" in Japanese

His serene self-assurance

静かで穏やかな表情

The autumn sky is clear and serene.

秋の空は澄み渡っている。

The view of Mars through earthly telescopes suggested that all was serene.

地上の望遠鏡で火星の様子を見ると、穏やかそのものだった。

And it makes you sound very serene, like you've had lots of Valium,

そうすると 安定剤を大量に飲んだみたいに とても穏やかに聞こえます