Great Comet of 1577
The Great Comet of 1577, seen over Prague on November 12, 1577. In addition to the comet, five zodiac symbols appear in the sky: (L-R) Aries, Pisces, Aquarius, Capricorn, and Sagittarius. Below the comet's tail are the crescent moon and Saturn, depicted as a star with the astronomical symbol ♄. At the bottom center, a man draws the comet by the light of a lantern. Engraving made by Jiri Daschitzky. Credit: Wikimedia Commons
The Great Comet of 1577 (C/1577 V1), one of the most important comets in the history of astronomy, was discovered in early November 1577. It was the first comet for which its location outside Earth's atmosphere was conclusively proven. The date of its first observations is uncertain. The comet could be first sighted in Peru on November 1 at dusk (November 2 UT), and in Mexico on November 4 or 6. On November 8, the Japanese recorded it as being as bright as the Moon and with a curved white tail stretching 50º. The glorious form of the comet showed up most impressively in the famous engraving by Jiri Daschitzsky that depicted its passage over Prague on November 12, 1577. By then the comet had already passed perihelion, which occurred on October 27 at 0.1775 au. It passed closest to the Earth on November 10 at 0,6271 au, and it was last seen on January 26, 1578.
Tycho Brahe (1546–1601), who is said to have first viewed the comet slightly before sunset on November 13 after having returned from a day of fishing, was the most distinguished observer and documenter of the comet's passing. Sketches found in one of Brahe's notebooks seem to indicate that the comet travelled close to Venus. Brahe made careful observations of the comet. Observing from his observatory at Uraniborg on the island of Hven near Copenhagen, Brahe determined the comet's celestial position with respect to certain reference stars using large quadrants that had a precision of four arc minutes, and compared these positions with those obtained at around the same time by another observer, Thadaeus Hagecius (1525–1600), who was 600 km away in Prague. By measuring the parallax for the comet, Brahe was able to show that the comet's distance was in excess of 230 Earth radii, which is approximately four times the distance to the Moon. Brahe's discovery that the comet's tail faced away from the Sun was also significant.
Tycho Brahe's observations of the comet were a milestone in the history of astronomy when he placed it in a supra-lunar position. This challenged the Aristotelian perception that comets were atmospheric phenomena. According to Aristotle (384–322 BC) — in his book Meteorologica, which dates to about 330 BCE — comets were dry and warm exhalations in the upper atmosphere that belonged to the sub-lunary sphere.
Tycho Brahe (1546–1601), who is said to have first viewed the comet slightly before sunset on November 13 after having returned from a day of fishing, was the most distinguished observer and documenter of the comet's passing. Sketches found in one of Brahe's notebooks seem to indicate that the comet travelled close to Venus. Brahe made careful observations of the comet. Observing from his observatory at Uraniborg on the island of Hven near Copenhagen, Brahe determined the comet's celestial position with respect to certain reference stars using large quadrants that had a precision of four arc minutes, and compared these positions with those obtained at around the same time by another observer, Thadaeus Hagecius (1525–1600), who was 600 km away in Prague. By measuring the parallax for the comet, Brahe was able to show that the comet's distance was in excess of 230 Earth radii, which is approximately four times the distance to the Moon. Brahe's discovery that the comet's tail faced away from the Sun was also significant.
Tycho Brahe's observations of the comet were a milestone in the history of astronomy when he placed it in a supra-lunar position. This challenged the Aristotelian perception that comets were atmospheric phenomena. According to Aristotle (384–322 BC) — in his book Meteorologica, which dates to about 330 BCE — comets were dry and warm exhalations in the upper atmosphere that belonged to the sub-lunary sphere.
Tycho Brahe's observations of the Great Comet of 1577. Credit: Wikimedia Common
© 2025, Andrew Mirecki
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