Abstract
Abstract. Aurora observations are an uncommon phenomenon at low and mid latitudes that, at the end of the 18th century, were not well known and understood. Low and mid geomagnetic latitude aurora observations provide information about episodes of intense solar storms associated with flares and outstanding coronal mass ejection (CME) and about the variation of the geomagnetic field. However, for many observers at mid and low latitudes, the features of a northern light were unknown, so they could easily report it as a phenomenon without explanation. In this work, we found that an earlier mid geomagnetic latitude aurora was observed in Beauséjour, close to Béziers (43∘19′ N, 3∘13′ E), France, by the abbot François Rozier. He was a meticulous botanist, doctor and agronomist with a special interest in atmospheric phenomena. On 15 August 1780, from 19:55 to 20:07 (Universal Time), François Rozier observed a “phosphoric cloud”. A careful analysis of the report indicates that he was reporting an auroral event. The recovery of auroral events at low and mid latitude during the 1780s is very useful for shedding light on solar activity during this period because there are few records of sunspot observations.
Highlights
Background and introductionIncursions of high-energy particles from space, mainly solar wind, strongly interact with the Earth’s magnetosphere, causing ionization and excitation of atmospheric gases and auroral emissions (Brekke, 2013; Gonzalez et al, 1994)
Low- and mid-latitude auroras (LMLAs) are usually associated with intense space weather events, frequently caused by coronal mass ejection (CME) (Gonzalez et al, 1994; Vázquez et al, 2006). This was the case with well-studied extreme space weather events such as those that occurred in September 1770 (Hayakawa et al 2017a); the Carrington event in August/September 1859 (Green and Boardsen, 2006; Green et al, 2006; Humble 2006; Tsurutani et al, 2003; Cliver and Dietrich, 2013; Hayakawa et al, 2019a); the storm on 1872 February (Hayakawa et al, 2018; Silverman, 2008); and the extreme events in September 1909 (Hayakawa et al, 2019b), May 1921 (Hapgood, 2019; Silverman and Cliver, 2001; Love et al, 2019) or March 1989 (Allen et al, 1989) resulting in extreme magnetic disturbances and auroral displays at very low latitudes
It seemed to me to have the whitish colour of phosphorus burning in the open air, or rather of that of mercury stirred in a tube without air
Summary
Background and introductionIncursions of high-energy particles from space, mainly solar wind, strongly interact with the Earth’s magnetosphere, causing ionization and excitation of atmospheric gases and auroral emissions (Brekke, 2013; Gonzalez et al, 1994). The aurora borealis is a spectacular phenomenon that has been recorded from the Assyrians and Babylonians (Stephenson et al, 2004; Hayakawa et al, 2016, 2019c) to nowadays It was not until 1733 that de Mairan (1733) suggested that the aurora could be caused by the solar atmosphere (Krivsky, 1984). Low- and mid-latitude auroras (LMLAs) are usually associated with intense space weather events, frequently caused by coronal mass ejection (CME) (Gonzalez et al, 1994; Vázquez et al, 2006). It is important to note that extreme space weather events of these magnitudes can provoke important impacts on our highly technologically dependent society, especially in activities related to aviation, GPS signals, radio communication, and electric power grids (Baker et al, 2008)
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