A great space weather event in February 1730

Abstract

Aims. Historical records provide evidence of extreme magnetic storms with equatorward auroral extensions before the epoch of systematic magnetic observations. One significant magnetic storm occurred on February 15, 1730. We scale this magnetic storm with auroral extension and contextualise it based on contemporary solar activity. Methods. We examined historical records in East Asia and computed the magnetic latitude (MLAT)Hayakawa et al. 2of observational sites to scale magnetic storms. We also compared them with auroral records in Southern Europe. We examined contemporary sunspot observations to reconstruct detailed solar activity between 1729 and 1731.Results. We show 29 auroral records in East Asian historical documents and 37 sunspot observations.Conclusions. These records show that the auroral displays were visible at least down to 25.8°MLAT throughout East Asia. In comparison with contemporary European records, we show that the boundary of the auroral display closest to the equator surpassed 45.1° MLAT and possibly came down to 31.5° MLAT in its maximum phase, with considerable brightness. Contemporary sunspot records show an active phase in the first half of 1730 during the declining phase of the solar cycle.This magnetic storm was at least as intense as the magnetic storm in 1989, but less intense than the Carrington event.

Sporadic auroras near the geomagnetic equator: in the Philippines, on 27 October 1856

“…It is not common for auroral displays to be seen anywhere near the geomagnetic equator. In some extreme magnetic storms, it is known that auroral displays were visible down to some 18 • to 30 • MLAT, such as those in the major storms of 1989, 1921, 1909, 1872, 1870, 1859, 1770, and 1730(Kimball, 1960Allen et al, 1989;Silverman, 1995Silverman, , 2006Silverman, , 2008Silverman and Cliver, 2001;Vaquero et al, 2008;Hayakawa et al, 2017Hayakawa et al, , 2018aEbihara et al, 2017;Willis et al, 1996), as partially reviewed by Cliver and Svalgaard (2004) and Cliver and Dietrich (2013). However, this value (3.3 • MLAT) is evidently closer to the geomagnetic equator, and is much lower than in the other events.…”

Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination

“…Another case is the great magnetic storm on 1730 February 15, as reviewed by Hayakawa et al (2018a). Weidler and Rhost (1731, pp.…”

Low-latitude Aurorae during the Extreme Space Weather Events in 1859

“…It is known that extreme interplanetary coronal mass ejections (ICMEs) released from sunspots can cause severe magnetic storms, especially when they have southward magnetic fields (e.g., Tsurutani et al, 1992Tsurutani et al, , 2008Gonzalez et al, 1994;Daglis, 2000Daglis, , 2004Daglis and Akasofu, 2004;Willis & Stephenson, 2001;Willis et al, 2005;Echer et al, 2008b;Vaquero et al, 2008;Vaquero & Vazquez, 2009;Schrijver et al, 2012;Odenwald, 2015;Lakhina & Tsurutani, 2016;Hayakawa et al, 2017c;Usoskin, 2017;Takahashi and Shibata, 2017;Riley et al, 2018). During magnetic storms, the horizontal component of geomagnetic fields decreases at low and middle latitudes (Gonzalez and Tsurutani, 1987;Gonzalez et al, 1994).…”