Page "Halley's Comet" Paragraph 4

Halley was the first comet to be recognized as periodic.

Until the Renaissance, the philosophical consensus on the nature of comets, promoted by Aristotle, was that they were disturbances in the Earth's atmosphere.

This idea was disproved in 1577 by Tycho Brahe, who used parallax measurements to show that comets must lie beyond the Moon.

Many were still unconvinced that comets actually orbited the Sun, and assumed they must instead follow straight paths through the Solar System.