Temple of Ranma's Sailor Senshi Seifuku

I just finished reading the story with Princess Kaguya, and something finally caught my attention. She was around back when the solar system was an "ugly cloud of stellar gas," as Pluto had put it. The thing is, it says 4.5 million years ago, where billion is more accurate.

I don't have this in Japanese, so I was wondering if it was translated wrong, or if it had been a mistake made by the author.

Naoko Takeuch SUCKS at technical knowledge
Give the lady some slack, will ya?

Never! She's so going down!