The Astronomia Nova, a book published 400 years ago that is now recognized as one of the most important works of the scientific revolution, has been included in an astronomy exhibition being held in Taipei, a highlight of the event that is set to conclude Sept. 13. The exhibition, titled '400 Years of Heavens Gazing, ' which is taking place at the Chiang Kai-shek Memorial Hall, has drawn more than 70,000 visitors since it opened Aug. 8, according to the National Science Council (NSC). After the organizers overcame great difficulties, the ancient book by 17th- Century German mathematician and astronomer Johannes Kepler was finally delivered to Taiwan Friday, just in time for the final two days of the exhibition, NSC officials said. Sun Wei-hsin, a professor of astrophysics at National Taiwan University who is one of the exhibition organizers, said they had to negotiate with the Astronomical Observatory of Vienna University for some time before it agreed to lend the book, a copy of the original edition, for the exhibition. It was one of the copies released in the first printing in 1609, and is now worth more than 230,000 euros (US$335,663), Sun said. The Astronomia Nova contains the results of Kepler's 10-year investigation of the motion of Mars and records the discovery of the first two of the three principles known today as Kepler's laws of planetary motion regarding the orbits of the planets. 