Comet 81P/Wild, also known as Wild 2 (pronounced “vilt two”), is a comet named after Swiss astronomer Paul Wild, who discovered it on January 6, 1978, using a 40-cm Schmidt telescope at Zimmerwald. The comet was estimated to be 15 km wide or 50% larger than the asteroid that wiped out the dinosaurs.
For most of its 4.5 billion-year lifetime, Wild 2 probably had a more distant and circular orbit. In September 1974, it passed within one million kilometers of the planet Jupiter, whose strong gravitational pull perturbed the comet’s orbit and brought it into the inner Solar System. Its orbital period changed from 43 years to about 6 years, and its perihelion continued to deteriorate from it’s original 1.59 AU (astronomical unit) until finally bringing it into a direct path with earth orbit on December 14, 2034.
Beginning in 1986, when it became apparent to the scientific community that the comet’s orbit would eventually bring it directly into earth’s orbit, the governments of the United States, the European Union and Russia began a secret program to either deviate or destroy the comet before its predicted collision with the earth.
To avoid mass pandemonium, scientists studying the comet were sworn to secrecy under penalty of violating National Security.