Differential Impact of an Eclipse on Photosynthetic Performance of Trees with Different Degrees of Shade Tolerance

Solar eclipses represent a natural and unexpected event for plants that can potentially affect photosynthetic performance at the individual level. This effect, however, has seldom been evaluated. Here, we measured the impact of a total solar eclipse on the photosynthetic rate of different tree species—located in the Bosque Fray Jorge National Park, Chile—with varying degrees of shade tolerance. Specifically, we assessed whether the rapid and progressive light limitation facilitated by a solar eclipse would negatively impact the photosynthetic responses of these tree species and whether their photosynthetic performance would have a greater decrease when the percentage of eclipse shadow was higher, particularly in the less shade-tolerant species. To accomplish this, we compared daily changes in the photosynthetic rates of three tree species during a control (non-eclipse) vs. an eclipse day that occurred on 2 July 2019. Overall, tree species showed differences between a non-eclipse and eclipse day in the daily dynamics of their photosynthetic performance, with this trend being most evident at the peak of the solar eclipse. Additionally, each species showed a different pattern of de-epoxidation in accordance with its degree of shade tolerance. Our results suggest that solar eclipses negatively affect the photosynthesis of the studied Chilean tree species, which may be related to energy dissipation capacity via the de-epoxidation of xanthophyll pigments. This effect was more evident in shade-intolerant species, indicating that eclipses can present different consequences for the overall performance of various plant species.

‘O+ + N2’ ÇARPIŞMASINA AİT REAKSİYON PARAMETRELERİNİN GÜNEŞ TUTULMASINA TEPKİSİ

The ionosphere is the part of the earth's atmosphere that extends from about 75 km to 1000 km. The sun is the main factor in shaping and dividing the ionosphere according to electron density. Therefore, the investigation and examination of solar-induced events is of great importance in understanding the structure of the ionosphere. The solar eclipses are one of the most important solar-induced events that cause sudden and medium-scale changes on the ionosphere. The solar eclipse of 29 March 2006 was observed as a total eclipse in some places and as a partial eclipse in some places. One of the regions recorded as a partial eclipse is Kharkov/Ukraine. In this study, the variations of reaction dynamics such as rate constant and cross section of the ‘O+ + N2’ collision, which is one of the ionosphere reaction processes, were investigated according to altitude (187 km) and local time during the 29 March 2006 solar eclipse over the city of Kharkov. The findings revealed that the changes in the reaction rate constant were similar to the changes in temperature, but the same similarities were not observed in the collision cross-section changes. According to another result obtained from this study, it has been determined that the use of experimental-based sources such as Kharkov incoherent scatter radar will give more effective results in investigating the effects of solar eclipses on the ionosphere.

Demonstrating Gravitational Lensing Using Solar Eclipses

As encouraged by the interesting paper “Solar eclipses as a teaching opportunity in relativity” by Overduin et al.,awe made measurements of the angular deflections of neighboring stars during the 9 March 2016 total solar eclipse as imaged by National University of Singapore (NUS) students, to verify a result of general relativity. In this project, we used these images and measured the stars’ pixel positions and transformed them to equatorial coordinates using a similar approach to Overduin et al., with a few modifications. Instead of solving to determine the pixel scale and rotation, we performed a plate solution using the software AstroImageJ which enables accounting for the image’s higher order distortion. This data is found in the image’s Flexible Image Transport System (FITS) header. Image star pair separations were then compared to their database separations after determining how the individual deflections affect angular separation. Our experimental results have large uncertainties and were deemed imprecise to confirm the effects of gravitational light deflection. We include a detailed analysis and discussion on this educational project.

Enigmatic Gravity Effects Observed during Solar Eclipses. Their Analyse by Quantum Model of Inertia and Gravitation

Foucault long pendulums, with spherical suspended mass, show Earth rotation by the constant velocity drift of their oscillation plane. Maurice Allais used a short, 84 centimeters pendulum, with a suspended bronze disc mass. He recorded its oscillation plane drift velocity, during solar eclipses, in 1954 and 1959. Both times, he noticed an anomalous drift of the oscillation plane. Several authors confirmed the effect, during next solar eclipses, with other types of pendulums. Then a group of Geophysicists, from the Science Academy of China, used an accurate digital gravimeter to measure Earth Gravity acceleration during March 09, 1997 solar eclipse. Their gravimeter recorded two drops of Earth Gravity acceleration (respectively 5.02 and 7.7 µ Gals) before and during first and last contacts of the Moon disc. However there was no acceleration drop during eclipse totality. Same phenomena were confirmed later, during next solar eclipses, with the same gravimeter. No classical causes for these facts were found, since modern gravimeters take care of temperature and atmospheric pressure variations. We analyse the effect of Moon rotation, and of solar Corona mass, in the frame of our Quantum model of Inertia and of Gravitation. The model predicts that Moon / Earth Gravity acceleration changes, when the Moon direction is close to the Sun one, as observed from the gravimeter place. That phenomenon should be tied to Quantum fluctuations dispersion by matter. Recorded measurements confirm that interpretation.

Aperiodic and wave disturbances in the ionosphere: the results of vertical sounding»

The monograph presents the study results of aperiodic and quasi-periodic wave perturbations in the ionosphere during unique phenomena in geospace: partial solar eclipses, the fall of the Chelyabinsk cosmic body and during the operation of a powerful radio source – the heating stand «Sura». Experimental data obtained by the method of remote sensing are analyzed. Designed for scientists in the field of ionosphere physics, radio physics, radar, as well as for lecturers, graduate and Ph.D. students.