TOKYO -- "Earth," the feature version of the hit BBC nature docu series "Planet Earth," has passed the Y2 billion ($18.5 million) mark, making it the biggest BO docu of the past ten years.

  "Earth" passed the previous top docu of the decade, Michael Moore's "Fahrenheit 9/11," which scored $15.9 million in 2004. The take also exceeded that of the hit French nature docu "March of the Penguin," which grossed $9.3 million in 2005.

  The pic, directed by Alastair Fothergil and Mark Linfield and narrated in Japanese by Ken Watanabe was released by Gaga Communications on 270 screens in Dec 1 and hit the Y1 billion mark after only ten days and passed the one million admissions milestone after 16 days.

  "Earth" is the second Gaga pic to achieve the two billion yen plateau since the company joined the Usen group in 2005. The first was Alexander Inarritu's drama "Babel," which Gaga released in April of last year.

  The all-time docu champion in Japan remains Kon Ichikawa's "Tokyo Olympiad," a near-three hour docu of the 1964 Tokyo Olympics that recorded Y1.25 billion ($11.7 million), when the average ticket price was Y178 yen ($1.66), compared with 1,216 yen ($11.36) in 2007.