Slow Fireball and Aurora Borealis

Amid raging disturbances in Earth’s magnetosphere caused by solar wind—the strongest since November 2003—a very slow bolide was recorded on May 10, 2024, late in the evening (22:43:23 CEST) by the cameras of the CEMeNt network. The bolide was captured by two cameras at the Valašské Meziříčí Observatory, as well as cameras at the Vsetín Observatory, Ždánice Observatory, Kysucké Nové Mesto Observatory, and a private station in Jablonec near Trnava. The spectrum of this relatively bright and slow meteor was also recorded. Combined with the ongoing geomagnetic storm, observers were treated to a fascinating view of both phenomena occurring simultaneously in Earth’s atmosphere.

The aurora borealis on the night of May 10–11, 2024, made history as it was observed as far south as Puerto Rico and Mexico, making it the southernmost recorded aurora in the Northern Hemisphere’s history of observations. In the Southern Hemisphere, it was visible, for example, from South Africa. This impressive event was caused by intense solar activity, with the Sun producing 10 strong flares the day before, primarily from the active sunspot region AR 3664. The combination of both phenomena is illustrated in the opening photograph taken by Marek Macko. The aurora borealis was documented by overview cameras of the CEMeNt network in numerous images, with the most interesting ones from Valašské Meziříčí (CZ), Partizánske (SK), and Jablonec near Trnava (SK) featured at the end of the article (Figs. 11–25).

The bolide 20240510_204323 was recorded by the CEMeNt network cameras on May 10, 2024, at 20:43:23.9 ± 0.1s UT. Within the Central European Meteor Network (CEMeNt), the bolide was directly captured by six wide-field cameras (Figs. 1–6). The bolide’s flight was documented from stations in Valašské Meziříčí SE and NE (CZ, Valašské Meziříčí Observatory), Ždánice E (CZ, Ždánice Observatory), Vsetín E (CZ, Vsetín Observatory), Kysucké Nové Mesto (SK, Kysucké Nové Mesto Observatory), and Jablonec near Trnava (SK, Jakub Kapuš). Additionally, the bolide’s spectrum was recorded by spectrographs at the Valašské Meziříčí Observatory (VM_SPSE and VM_SPNE spectrographs). Unfortunately, the spectrum was very faint, and its signal-to-noise ratio was insufficient for thorough analysis. However, a preliminary view of the spectrum suggests that the bolide was a sodium-rich (Na-enhanced or Na-rich) body.

Atmospheric Path, Radiant, and Heliocentric Orbit of the Fireball

To calculate the atmospheric trajectory of the fireball and the meteoroid’s orbit within the Solar System, recordings from the stations in Valašské Meziříčí NE and SE, Kysucké Nové Mesto, Vsetín E, and Jablonec N were used. These recordings were captured using the UFO Capture program, processed with UFO Analyzer, and the atmospheric and heliocentric paths were calculated in UFO Orbit.

The projection of the beginning of the atmospheric path was located at coordinates N49.622467° E18.939476°, near the village of Cienków (PL), east of Wisła (PL), at an altitude of 78.9 km above Earth’s surface. The projection of the end of the atmospheric path was at coordinates N49.22398° E19.080387°, near the village of Štefanová (SK), east of Žilina (SK), at an altitude of 35.3 km above Earth’s surface (Fig. 7). These geographic coordinates and altitudes are based on the fireball trajectory calculation, excluding images of the fireball from the beginning and end of the ablation path.

When all ablation path images are included, the initial altitude of the observed atmospheric path of the fireball is 81.1 km, and the final altitude is 32.6 km. The fireball reached an absolute magnitude of -3.2m and covered a distance of 63.4 km in Earth’s atmosphere during its 6.2-second flight.

The object entered Earth’s atmosphere at an optimal angle of 44.2°, with a pre-atmospheric velocity of 12.51 km/s, classifying it as a very slow bolide. The meteoroid’s geocentric velocity was 5.73 km/s (Table 1). It was not associated with any known meteor shower, making it a sporadic meteor. Before entering the atmosphere, the object followed a slightly eccentric orbit (Fig. 8) with low eccentricity (e = 0.179), a low inclination to the ecliptic plane (i = 7.28°), and a perihelion distance of q = 0.9336. The object had an asteroidal origin, with an unknown parent body. Based on orbital similarity criteria, the closest known asteroid is 2014 HG197 (DD = 0.097).

Table 1: Atmospheric path, heliocentric and geocentric orbital elements of fireball 20240510_204323, including the effect of deceleration on the trajectory. (*) denotes the initial and final heights from the calculation of the object's heliocentric orbit. Author: Jakub Koukal

Physical Properties of the Meteoroid

To estimate the initial mass of the object and its other physical properties, the heliocentric orbital elements and atmospheric trajectory of fireball 20240510_204323 were analyzed. The Tisserand parameter relative to Jupiter was calculated for the initial determination of the meteoroid’s heliocentric orbit. Based on the Tisserand parameter, orbital inclination, and aphelion distance, objects can be categorized into four groups. Fireball 20240510_204323 has a Tisserand parameter value of TJ = 5.489, placing it in the AST group, which includes meteoroids of asteroidal origin. However, according to the KB parameter (7.542), which depends on material properties and surface temperature, it belongs to the group of carbonaceous chondrites. Based on the PE parameter (-4.126), the fireball is classified among ordinary chondrites. Using parameters characterizing the shape, velocity, and other properties of the object (Table 1), the initial and final mass of the meteoroid was calculated.

Parallel to the calculation of the dynamic entry mass (md), the photometric entry mass (mf) was also calculated. The initial dynamic mass of the meteoroid before entering Earth’s atmosphere was determined to be 0.77 kg (md). The calculation of the meteoroid’s fragmentation strength is based on the equality of dynamic pressure and the structural strength of the body at the moment of its disintegration. Atmospheric parameters at the altitude of disintegration were calculated using the NRLMSISE-00 (2002) model.

The moment of the meteoroid’s disintegration (fragmentation) was determined from the absolute magnitude values of the fireball recorded at the Valašské Meziříčí SE station (Fig. 10) and from the analysis of recordings from the Vsetín E station. During the ablation trajectory, several fragments separated from the main body (Fig. 9). The fragmentation strength of the main body was calculated as 0.120 MPa (Fragment A), 0.164 MPa (Fragment B), and 0.200 MPa (Fragment C), classifying the meteoroid as part of the group of ordinary chondrites (OC). The determined mineralogical density of the body (3.28 g/cm³) further suggests that fireball 20240510_204323 was a body belonging to ordinary chondrites, originating from the Apollo-type asteroid group.

Fig. 11-16: Images of the aurora borealis on the night of May 10–11, 2024, captured by the overview camera at Valašské Meziříčí NE. Author: Valašské Meziříčí Observatory, p.o.

Fig. 17-22: Images of the aurora borealis on the night of May 10–11, 2024, captured by the overview camera at Jablonec N. Author: Jakub Kapuš

Fig. 23-25: Images of the aurora borealis on the night of May 10–11, 2024, captured by the overview camera at Partizánske NW. Author: Partizánske Observatory

Acknowledgments

Acknowledgments go to all operators and station owners of the CEMeNt network. Further thanks go to all involved institutions for supporting the activities and growth of the network. The RPOS project (Development of Cross-Border Observation Network) was co-financed by the Small Projects Fund of the Interreg V-A Slovakia–Czech Republic 2014–2020 program, call code 5/FMP/11b, reg. no. CZ/FMP/11b/05/058.

The KOSOAP project (Cooperating Network for Astronomical Expert Observation Programs) and the RPKS project (Development of a Cross-Border Cooperating Network for Expert Work and Education) were carried out by the Valašské Meziříčí Observatory (Czech Republic) and the Kysucké Nové Mesto Observatory (Slovakia) in cooperation with SMPH (Society for Interplanetary Matter). These projects were co-financed by the Microprojects Fund of the Cross-Border Cooperation Operational Program Slovakia–Czech Republic 2007–2013.

The project for the purchase and operation of high-resolution spectroscopic cameras was partially funded by the Regional Cooperation Program of the Czech Academy of Sciences, reg. no. R200402101, and the APVV-0517-12 grant (FMFI UK). The acquisition of equipment for the Valašské Meziříčí Observatory was also supported by DEZA, a.s., and CS CABOT, spol. s r.o.