9 February 1986

Halley’s Comet last appeared in the inner Solar System.

Halley’s Comet is one of the most famous comets known to humanity. It’s named after the English astronomer Edmund Halley, who, in 1705, predicted its return based on observations of previous sightings dating back to 1531, 1607, and 1682. The comet itself has a long and elliptical orbit that brings it close to the Sun and then back out into the far reaches of the solar system. Its orbital period is approximately 75-76 years.

Appearance: Halley’s Comet is known for its distinctive appearance, with a bright coma (a cloud of gas and dust) surrounding its nucleus and a long tail extending millions of kilometers into space. The tail always points away from the Sun due to solar wind and radiation pressure.

Observations: Throughout history, Halley’s Comet has been observed and recorded by various civilizations. The earliest confirmed sighting was in 240 BC by Chinese astronomers. Its appearance has been noted in numerous historical records, including European, Islamic, and Asian sources.

Scientific significance: Halley’s Comet is significant to scientists because it provides insights into the composition and behavior of comets, which are remnants from the formation of the solar system. Studying its composition helps scientists understand the early conditions of the solar system.

Notable appearances: Halley’s Comet has made several notable appearances throughout history. One of the most famous was in 1066 when it appeared in the sky shortly before the Battle of Hastings in England. Another notable appearance was in 1910 when Earth passed through the comet’s tail, leading to widespread fear and speculation about potential effects (though no harm came from it).

Recent appearances: Halley’s Comet was last visible from Earth in 1986. Its next expected appearance is around the year 2061.

Spacecraft missions: Several spacecraft have been sent to study Halley’s Comet up close. The most notable mission was by the European Space Agency’s Giotto probe, which flew within 600 kilometers of the comet’s nucleus in 1986, providing valuable data and images.