81P/Wild

Comet 81P/Wild, also known as Wild 2 (pronounced "vilt two"), is a comet that returns to the inner Solar System every 6.4 years. It was named after the Swiss astronomer Paul Wild, who first saw it on January 6, 1978. He used a special 40-cm Schmidt telescope in Zimmerwald, Switzerland.

For most of its long life—about 4.5 billion years—Wild 2 moved in a steady path far from the Sun. In September 1974, something changed: the comet passed very close to the giant planet Jupiter. Jupiter's strong gravity changed Wild 2’s path. This event shifted the comet’s orbit from a slow 43-year cycle to a quicker 6-year cycle. Now, Wild 2 comes closer to the Sun.

Wild 2 becomes visible from Earth roughly every six years. This gives scientists and stargazers a chance to see this icy traveler up close. Its journey helps us learn about the early Solar System and the building blocks of planets and other worlds.

Orbit

Before 1974, Comet 81P/Wild went around the Sun every 43 years. It traveled far from the Sun and then close to it. In September 1974, the comet passed near the planet Jupiter. Jupiter's strong gravity changed the comet's path. This made the comet's orbit shorter and brought it closer to the Sun more often. Now, the comet goes around the Sun every 6.4 years.

Exploration

Wild 2 from Earth

NASA launched the Stardust spacecraft on February 7, 1999. It flew by Wild 2 on January 2, 2004, collecting particle samples from the comet's coma. These samples, along with interstellar dust collected during the journey, were returned to Earth on January 15, 2006.

The close-up images showed the comet's surface had flat areas and steep walls. Scientists studied the collected particles and found different materials, including crystals that form when things get very hot. This suggests parts of the comet were once much closer to the Sun than they are now.