The title of a manga I'm slowly working through is 惑星のさみだれ, but there is furigana above the two kanji that says ほし (star) instead. Why did it use both kanji, which seems to be normally read as わくせい (planet) when it could have used just 星 on it's own?
Japanese often refer to planets as ほし as well when they're being informal, the manga is just specifying that it's a planet and not actually a star.
I guess you could say it's a stylistic choice.
ほし means any heavenly body except the sun and the moon. And while ほし is most often heard used with stars, it is also used for "planet". This could just be related to lyrics in that both kanji mean planet, but decided to go with these kanji and this pronunciation for a poetic effect.