NASA Solar System Exploration

In 1986, the European spacecraft Giotto became one of the first spacecraft ever to encounter and photograph the nucleus of a comet, passing and imaging Halley's nucleus as it receded from the Sun. Credit: Halley Multicolor Camera Team, Giotto Project, ESA | More about this imageHalley is often called the most famous comet because it marked the first time astronomers understood comets could be repeat visitors to our night skies. Astronomers have now linked the comet's appearances to observations dating back more than 2,000 years.Halley was last seen in Earth's skies in 1986 and was met in space by an international fleet of spacecraft. It will return in 2061 on its regular 76-year journey around the Sun.The History of Halley's CometUntil the time of English astronomer Edmond Halley (1656-1742), comets were believed to make only one pass through the solar system.But in 1705, Halley used Isaac Newton's theories of gravitation and planetary motions to compute the orbits of several comets. H...