Great Comet of 1577

Lore & Background

Tycho Brahe, who first viewed the comet slightly before sunset on 13 November after returning from a day of fishing, made thousands of precise measurements using a 16-inch radius quadrant and a simple sextant. His observations led him to believe the comet was outside the orbit of the Sun and Moon. By comparing the comet's position as seen from Hven (near Copenhagen) with that observed by Thadaeus Hagecius in Prague, and accounting for the Moon's movement, Brahe proved the comet was beyond the Moon's orbit, probably about three times further away. Brahe also discovered that the comet's coma faced away from the Sun. Sketches in his notebook show the Earth at the center, with the Sun and Moon in orbit and other planets revolving around the Sun.

Reader's Guide

The Great Comet of 1577 was notable for the breadth of its observation and the debates it sparked. Brahe's finding that comets were heavenly objects, while widely accepted, caused debate into the seventeenth century; Galileo claimed comets were optical phenomena, but his hypothesis was not widely accepted. The comet inspired artists such as Jiri Dschitzky, who made an engraving of it over Prague, and Cornelis Ketel, who painted Richard Goodricke with the comet as an omen. It also appeared in literature, including Chaim Vital's The Book of Visions, and in numerous broadsides. The comet was recorded in the Vietnamese chronicle Đại Việt sử ký toàn thư, the Chinese History of Ming, and the Irish Annals of the Four Masters. Sultan Murad III saw it as an evil omen, while Michael Mästlin used it to fill gaps in Copernicus's model. Brahe's measurements contributed to Johannes Kepler's laws of planetary motion and the realization that planets move in elliptical orbits.

Did You Know?

• Brahe proved the comet was beyond the Moon's orbit by comparing its position from Hven and Prague.
• The comet was recorded in the Codex Aubin as a 'smoking star' on 6 November 1577.
• Sultan Murad III saw the comet as a bad omen for war.