Tycho Brahe, Abū Ma^cshar, and the comet beyond Venus (ninth century A.D.)

Abstract

From his observations of the a.d. 1572 supernova and the a.d. 1577 comet, Tycho Brahe concluded that such transient celestial objects are outside the Earth’s atmosphere, and he quoted the ninth century a.d. Persian astrologer and astronomer Abū Macshar: Dixit Albumasar, Cometa supra Venerem visus fuit; i.e., the latter had reported much earlier that comets were seen beyond Venus. However, even from a more detailed Latin translation, the observations and logic behind Abū Macshar’s conclusion were not understandable. We present here the original Arabic text (manuscript Ankara, Saib 199) together with our translation and interpretation: Abū Macshar reported that he had observed Venus in (or projected onto) the tail of a comet and concluded that the comet was behind Venus because he had observed the extinction of Venus due to the cometary tail to be negligible (light of Venus was unimpaired). He then concluded that the comet would be located behind Venus. He also mentioned that others had observed Jupiter and Saturn in cometary tails, so that those comets would even be located beyond those two outer planets – in the sphere of the stars. The dates of the observed close conjunctions were not mentioned; using known orbital elements for a few comets, we found a few close conjunctions between comets and planets from a.d. 770 to 868, but we cannot be sure regarding which conjunctions were reported. While the argument of Abū Macshar is not correct (as cometary tails are optically thin), the conclusion – namely that comets are outside the Earth’s atmosphere and beyond the moon – is correct. This may have helped Tycho Brahe to come to his revolutionary conclusion.

Critical comments on publications by S. Hoffmann and N. Vogt on historical novae/supernovae and their candidates

“…Ho (1962) listed events, which could in principle be comets or (super-)novae from the Chinese text corpus (until AD 1600). Xu et al (2000) revised this compilation 8 For example, the reference in P3 and P5 to Neuhäuser et al (2018c) is just a summary in German, but should be R. Neuhäuser et al (2016a), the original English publication. 9 P3 (section 2.1) present the following selection steps: "1.…”

Counterparts of Far Eastern Guest Stars: Novae, supernovae, or something else?

“…• An observation by astronomers of different cultures who usually use different constellations could help to improve the positioning of the observation by using the intersection of the reported constellations (Neuhäuser et al 2018). In many other science cultures, the 'research focus' was different and was triggered by other religious beliefs.…”

A new approach to generate a catalogue of potential historical novae

“…During the last 10 years, several scholars have used historical data to draw conclusions on astrophysical questions, for example, concerning the development of close binary systems. For historical supernovae, this has been achieved for several decades (starting with Schlier ; Baade ), and for solar activity as well as for improving orbital elements of comets by usage of historical data, for example, Neuhäuser et al () and Neuhäuser et al () also proved this concept to contribute to the current state of research. Thus, the idea of using old data caused the interest in research on cataclysmic variables (CVs) culminating in papers by Shara+ in the recent years (Shara et al ; Shara et al ; Shara et al ).…”