It is believed that for most of its 4.5 billion-year lifetime, Wild 2 had a more distant and circular orbit. In 1974, it passed within only about one million kilometers of the planet Jupiter, whose strong gravitational pull altered the comet's orbit and brought it into the inner solar system. Its orbital period changed from 40 years to about 6 years, and its perihelion is now about 1.59 AU (astronomical unit).