Consideratio & observatio cometae aetherei astronomica qui anno MDLXXX mensibus octobri, novembri et decembri in alto aethere apparvit

XIII

...it seemed to have clearly continued its motion of longitude, as if it, which had been retrograde until now, wished to be direct hereafter; but it decreased its latitude or northern declination more and more daily.

Comet very obscure, larger then than Venus. On the 2nd day of October, the day it was first seen by me, it lacked any tail, having an orbicular figure, surrounded by hairs all around. It exceeded Venus in magnitude, but could in no way be compared to it in the clarity of its light. For it shone with a very dull and obscure or blackish color, not unlike an obscure and nebulous star.

On the 8th of October, it began to be slightly brighter and somewhat whitish, yet still without a tail.

The Comet finally made tailed on the 9th. On that day, finally, I hear that its presence became known to many everywhere. On the next day, a dull brightness, designating its mane or tail, began to shine. On that day, therefore, it first revealed itself to be a hairy star, or, if you prefer, a Pogonias bearded comet.

Length of the Comet. The length of the tail did not appear equal to that which we saw three years ago. On October 10th, it seemed to equal or even exceed 4 1/2 degrees. But in the following days, when I would observe its length while the Moon was absent, both I and the others who were with me—who were observing with no dull vision—noticed that the length of the tail, if not greater, was certainly not much shorter than that which we saw with great horror in the year 1577. For rays were emerging from the head in a long tract, extending themselves beyond a twelfth part of the sky. They were, however, very obscure and dark, so much so that (which is not unworthy of admiration) they could only be observed by those looking obliquely, and not by those looking directly. From this, we could conclude that if the clarity of its splendor had corresponded to its magnitude, it would by no means have remained unknown for so long. It was common to the tail, as in all Comets observed until now...