Abstract
Cometary tails visually manifest the solar wind and became an initial hint for its discovery. While the solar wind is being directly monitored with satellites, its time series before the space age has been controversially reconstructed with multiple proxies. Recently, archival reports of cometary plasma tails have been subjected to consideration to indirectly measure the solar wind but brought conclusion that no plasma tails had been reported prior to 1769 probably due to their brightness. However, historical records have occasionally reported comets with two tails even before 1769. These cases have been tentatively associated with visual reports of cometary plasma and dust tails. Therefore, we examined three such cases (C/1577 V1, 1P/837, and 1P/760), and compared the descriptions in historical records with calculated direction of their plasma tails. Our comparisons show that the records and calculations agree in these cases and plasma tails were visually recorded corresponding to these three great comets. These cases certify the capability of plasma tail observations with the unaided eye even before 1769, qualitatively imply their extreme brightness, proximities with the Sun and the Earth, relative enhancements of UV radiations, and interaction of cometary neutral atmosphere with solar wind plasma and magnetic field, while the lack of their detailed length or kink hinders us from their quantitative measuring. Further investigations will likely lead to the re-discovery of even more visual evidence of cometary plasma tails and, hence, improve our understanding on past space climate.
Highlights
Pointing almost towards the antisolar direction (Fig. 1), the cometary tails have provided visual hints for the solar wind (Biermann, 1963; Abe et al, 1997; Mendis, 2007; Vaquero & Vázquez, 2009; Mendis and Horányi, 2013; Iju et al, 2015; Verscharen et al, 2019)
Before the onset of such modern monitoring, the time series of the solar wind has been controversially reconstructed on the basis of multiple proxies such as the sunspot number, coronal structure, magnetic indices, and cosmogenic isotopes (Lockwood et al, 1999; Svalgaard & Cliver, 2005; Owens et al, 2017; Usoskin, 2017; Cliver & Herbst, 2018), including that of the Maunder Minimum (Cliver et al, 1998; Svalgaard & Cliver, 2007; McCracken & Beer, 2014; Riley et al, 2015; Usoskin et al, 2015; Owens et al, 2017)
It is challenging to extend its reconstructions before the onset of sunspot observations in 1610 due to the limit of direct scientific observations (Vaquero & Vázquez, 2009; Owens, 2013), while the cosmogenic isotopes in the natural archives show us its variability on the basis of the anti-correlation between the solar-wind magnetic field and the source galactic cosmic rays (e.g., Beer et al, 2012)
Summary
Pointing almost towards the antisolar direction (Fig. 1), the cometary tails have provided visual hints for the solar wind (Biermann, 1963; Abe et al, 1997; Mendis, 2007; Vaquero & Vázquez, 2009; Mendis and Horányi, 2013; Iju et al, 2015; Verscharen et al, 2019). They examined the shape, orientation, and colouration of cometary tails in historical documents, pointed out the lack of mentions on the plasma tail in historical records before C/1769 P1 (Fig. 2), and explained their conclusion with poor visibility of plasma tails through unaided-eye observations or early telescopes. In this article, we discuss three case reports of great comets (C/1577 V1, 1P/837, and 1P/760) with two tails and compare their descriptions with simulated orientations of the cometary tails, in order to determine whether plasma tails were visible before C/1769P1 (c.f., Zolotova et al, 2018) and whether cometary records can be used to progress in our understanding of the space climate in the past
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
