Giotto spacecraft at Halley's Comet. Artwork of the European Space Agency's (ESA) Giotto probe as it approached Comet Halley in 1986. It passed the comet at a distance of 600 kilometres and beamed back pictures and scientific data. The probe was just under 2 metres long and weighed just under a tonne. It was launched in July 1985. Its closest approach was on 13 March 1986. Halley's Comet is a short-term comet, orbiting the Sun every 76 years. Edmund Halley (1656-1742) discovered this regular behaviour. Comets are bodies of ice and dust from the outer solar system. The ice boils near the Sun to form a long bright tail in the solar wind.