Magnetosphere of Jupiter By 1973 the magnetic moment was known within a factor of two, whereas the tilt was correctly estimated at about 10°. The modulation of Jupiter's DAM by Io (the so-called Io-DAM) was discovered in 1964, and allowed Jupiter's rotation period to be precisely determined. The definitive discovery of the Jovian magnetic field occurred in December 1973, when the Pioneer 10 spacecraft flew near the planet. As of 2009 a total of eight spacecraft have flown around Jupiter and all have contributed to the present knowledge of the Jovian magnetosphere. The first space probe to reach Jupiter was Pioneer 10 in
Mission: Earth, Voyage to the Home Planet book might be used more successfully to supplement the curriculum in those areas than in units on space flight per se". Weischedel said the book "provides a unique look at a new method of research and an opportunity for youngsters to read one scientist's account of what it's like to engage in this exciting field of endeavor". "Horn Book Review" called the book "a uniquely personal account", and said it "features a crowded design, but the many color photographs throughout the text are fascinating". "Mission: Earth, Voyage to the Home Planet" is listed in the book "Teaching U.S. history through