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The results obtained during the total Solar Eclipse on July 2, 2019, in Chile are presented together with the Eclipse K-corona Polarimeter (EKPol). The EKPol is equipped with an electro-optically modulating Liquid-Crystal Variable Retarder (LCVR) for the polarimetric observation of the solar corona. The use of this technology has been an important ground-based test for the application of this technology in space-based observatories. The usage of LCVRs in a polarization rotator configuration allows the replacement of mechanically rotating retarders avoiding moving parts and reducing noise, failure probability, and mass. Indeed, EKPol was developed as a technology demonstrator for the Metis coronagraph on-board Solar Orbiter. The results, from the composition of the image to the electron density map evaluation, are compared and are consistent with what is obtained by other ground- and space-based instruments, and with past EKPol campaigns.

On 8 April 2024, a rare total solar eclipse (TSE) passed over western New York State (NYS), the first since 1925 and the last one until 2079. The NYS Mesonet (NYSM) consisting of 126 weather stations with 55 on the totality path provides unprecedented surface, profile, and flux data and camera images during the TSE. Here we use NYSM observations to characterize the TSE's impacts at the surface, in the planetary boundary layer (PBL), and on surface fluxes and CO2 concentrations. The TSE‐induced peak surface cooling occurs 17 min after the totality and is 2.8°C on average with a maximum of 6.8°C. It results in night‐like surface inversion, calm winds, and reduced vertical motion and mixing, leading to the shallowing of the PBL and its moistening. Surface sensible, latent and ground heat fluxes all decrease whereas near‐surface CO2 concentration rises as photosynthesis slows down. Plain Language Summary On 8 April 2024, a rare total solar eclipse (TSE) passed over western New York State (NYS), the first one since 1925 and the last one until 2079. The entire NYS witnessed at least 88% obscuration at the peak of the eclipse. It provides an excellent opportunity to study the impacts of the TSE. The NYS Mesonet (NYSM), an advanced statewide weather network, has 55 stations on the totality path and provides unprecedented measurements of surface meteorological variables, atmospheric vertical profiles, the heat exchange between the atmosphere and the surface and carbon dioxide (CO2) concentration. It enables one to study the TSE in greater details on a regional scale for the first time. This study found that the moon shadow cools the surface by as much as 6.8°C and creates a surface inversion layer. The cooling calms down winds and vertical mixing, leading to less escape of the water vapor and moistening of the air. It also reduces the heat exchange between the surface and the air. Without sunlight, the photosynthesis shuts down, causing a robust rise in near‐surface CO2 concentration. One‐minute camera images provide a fantastic view of the darkening of the sky during the TSE. Key Points The New York State Mesonet provided unprecedented surface, profile, flux and image data during the 8 April 2024 total solar eclipse across New York State The eclipse resulted in significant cooling and moistening near the surface and in the boundary layer, leading to a surface inversion layer It also weakened surface winds, turbulent mixing, heat fluxes, but caused a robust rise in near‐surface CO2 concentrations

The path of eclipse totality across North America, Spain, and Northern Africa on 18 July 1860 was accessible to a wide range of observers in diverse geographical and socio-political contexts, the infrastructures of which shaped individual expedition logistics. This joint paper combines in a single frame of reference accounts from British, French, Spanish, Portuguese, Italian, Algerian, and North American expedition parties. A focus on the scientific objectives of these observers with varied circumstances, institutions, and funding sources raises the question of a global approach to the history of observing the total solar eclipse in 1860.

In the United States, techniques that would one day be called astrophysical were applied later than elsewhere and comparatively suddenly. Their entry into US main-stream astronomy was motivated by a quasi-stochastic phenomenon: a total eclipse of the Sun visible between the contiguous borders of that country. In reaction to the upcoming event, the US Nautical Almanac Office in particular invested time, workforce, and a great deal of money into the measurements of physical astronomy, especially spectroscopy. This occurred although none of its employees had ever expressed—at least, in writing—expertise or even interest in the subject beforehand. Once adopted, physical astronomy, and the investigations it enabled, moved slowly, but steadily, into the mainstream of American astronomy despite objections from traditionalists. In the twenty-first century, spectroscopy and other physical astronomy techniques are essential tools for all astronomers.

A total solar eclipse provides an unparalleled opportunity to study the changes in the atmosphere’s planetary boundary layer (PBL) due to changes in radiative heating. Although previous eclipse studies have demonstrated that significant changes occur, few studies have explored the evolution of these changes. To better understand the changes in the lowest layers of the PBL during an eclipse, a multi-sensor sampling approach was taken. Radiosonde launches were used to explore the depth of the column, while Unmanned Aerial Vehicles (UAVs) were used to document with high-resolution the brief changes in the vertical structure of the PBL caused by the eclipse. These changes highlighted differences from previous studies that relied solely on radiosonde and/or mesonet data alone. Higher-resolution sampling of the lower PBL showed a delay in the local vertical mixing as well as changes in the PBL height from pre- to post-eclipse. Slow responses were noted at the top of the PBL while very rapid changes to the PBL profile were captured in the near-surface layer. These changes highlighted differences from previous studies that relied solely on radiosonde and/or mesonet data alone. A preliminary analysis of the collected data highlighted a slow response to the eclipse near the top of the planetary boundary layer (radiosonde data) with very rapid changes noted in the near surface layer (UAV data). Preliminary results show that PBL heights remained nearly constant until well after third contact when a 35 hPa lowering of the PBL heights was observed and were limited to the lowest 25 hPa. The UAV soundings demonstrated the development of a strong inversion where the air below 990 hPa rapidly cooled with a nearly 1 °C drop in temperature observed. These observed changes raise interesting questions about how the lower and upper parts of the planetary boundary layer interact.

Observations of tweeks with higher harmonics (n > 1) at low latitude stations Allahabad and Nainital, in the Indian sector, during the total solar eclipse on 22 July 2009, are presented. Allahabad and Nainital stations were in 100% and 85% of the totality paths. Observations suggest that about 30–40% obscuration of solar disc can lead to the tweeks occurrence which otherwise occur only in nighttime. A total of 148 tweeks at Allahabad and 20 tweeks at Nainital were recorded with some of them up to 3rd harmonics. The World Wide Lightning Location Network data indicated that tweeks observed were generated by lightning's located in the partial eclipse area of Asia‐Oceania region. The changes in D‐region ionospheric VLF reflection height and electron density (∼22–23 cm−3) during eclipse have been estimated from the first cut‐off frequency of the tweeks. The reflection height increased from ∼89 km from the first occurrence of tweek to about 91–92 km at the totality and then decreased to ∼87 km at the end of the eclipse, suggesting a change of about 5 km in the reflection height during eclipse. The reflection heights are lower by 2–3 km as compared to normal nighttime tweek reflection heights. The above increase in the reflection height indicate that the partial nighttime condition is created during eclipse, as the main D‐region ionizing radiation Lyman α is blocked but solar soft X‐ray and EUV radiations originating from the limb solar corona are not totally blocked which produce some of ionization in the D‐region. Key Points Study of total solar eclipse effect on D‐region ionosphere Rare observation of tweek radio atmospherics during total solar eclipse Solar eclipse time D‐region ionosphere modulation studied from tweeks observation

This paper reports the observation of performance solar cells when the total solar eclipse occurs in central Sulawesi, Indonesia. The observation was done by measuring some parameter and calculating the performance of solar cells. It was found that performance of solar cell was decreased linearly before total solar eclipses happen and its performance increase after the total solar eclipse. The performance of a solar cell when a total solar eclipse occurs is nearly zero because the intensity of the light measured by the instrument is equal to zero. It was concluded that the performance of solar cells was influenced by the intensity of light.

The total solar eclipse of 21 August 2017 was unique in that the path of totality swept across the high spatial and temporal resolution QuantumWeather® mesonet and was very near the city of St. Louis Missouri. Thus, the meteorological response to the eclipse was complicated by the St. Louis urban heat island. Temperature changes of up 4 °C were observed across the network. Composite meteograms for rural, suburban, and urban stations displayed significant differences in the observed temperature and pressure response to the eclipse with a peak amplitude at the time of the eclipse. The differing response suggests that the urban heat island and changes in land surface characteristics alter the temperature and pressure response by the passage of the eclipse shadow. Oscillations in the composite meteograms appear to be the consequence of the passage of an outflow boundary across the network. As the outflow boundary moves north to south, the outflow boundary manifests its presence in the pressure field as a damped oscillation. Sounding data were collected along the center line of eclipse and along the southern edge of the eclipse before and during the eclipse. The soundings show that the eclipse altered the boundary layer height, the lowest layer of the atmosphere, in an unexpected way.

The behaviour of remotely sensed land surface temperatures (LSTs) from the spinning-enhanced visible and infrared imager (SEVIRI) during the total solar eclipse of 20 March 2015 is analysed over Europe. LST is found to drop by up to several degrees Celcius during the eclipse, with the minimum LST occurring just after the eclipse mid-point (median=+1.5 min). The drop in LST is typically larger than the drop in near-surface air temperatures reported elsewhere, and correlates with solar obscuration (r=−0.47; larger obscuration = larger LST drop), eclipse duration (r=−0.62; longer duration = larger LST drop) and time (r=+0.37; earlier eclipse = larger LST drop). Locally, the LST drop is also correlated with vegetation (up to r=+0.6), with smaller LST drops occurring over more vegetated surfaces. The LSTs at locations near the coast and at higher elevation are also less affected by the eclipse. This study covers the largest area and uses the most observations of eclipse-induced surface temperature drops to date, and is the first full characterization of satellite LST during an eclipse (known to the author). The methods described could be applied to Geostationary Operational Environmental Satellite (GOES) LST data over North America during the August 2017 total solar eclipse. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’.

Astronomical observations have been documented in pre-Hispanic cultures. However, little is known about the astronomical heritage of pre-Hispanic societies in Venezuela, since there are no evidence of an ancestral material culture as other regions of Meso and South America, and these native Venezuelan groups lacked a written, alphabetic or ideographic language. There are innumerable petroglyph deposits in almost all regions of Venezuela, especially near Lake Valencia (Carabobo state) and those of the Andean foothills (Barinas state). By means of computerized simulation and archaeoastronomy techniques, the occurrence of a total solar eclipse is verified: in July 1, 577 at the Vigirima site; and another total solar eclipse at noon on May 16, 1398 at the Bum Bum site. It is concluded that the contemplation of the total eclipses of the Sun, must lead to the need for communication and recording, and lacking any type of writing, they drew the phenomenon, using the techniques and means at their disposal: engraving on rocks.