Solar eclipse

About: Solar eclipse is a research topic. Over the lifetime, 2737 publications have been published within this topic receiving 22625 citations.

Modeling of the ionospheric response to the solar eclipse of 24 October 1995

Abstract: In this paper the ionospheric effects of the solar eclipse of October 24, 19995 were investigated using a two-dimensional ionospheric theoretical model. In the calculations, only the depression of solar EUV fluxes during the course of the eclipse was taken into account under the solar eclipse condition.(1)During the period of the eclipse, the optical effects were quite clear at the lower altitudes of the ionosphere, while the responses to the eclipse were weaker, delayed, but longer in duration at the higher altitudes.(2)The lower the magnetic latitude, the stronger was the response to the solar eclipse. In low latitude regions, the values of f。F2 on the eclipse day were lower compared with those under the control conditions, whereas hmF2 values were higher.(3)Near the magnetic equator there was a sharp transition in hmF2 after the maximum phase of obscuration, and a solar F1.5 layer appeared below the normal peak height of the F2 layer.(4)After the maximum phase, the effects of the eclipse lasted longer near Hainan, and a secondary depression occurred over the magnetic equator. The mechanisms that may be responsible for the eclipse-caused effects are discussed here.

A radio determination of the time of the New Moon

Abstract: SightinganddetectionoftheNewMoonatsunsetisofimportancetocommunitiesbasedonthe lunar calendar. This is traditionally undertaken with visual observations. We propose a radio method which allows a higher visibility of the Moon relative to the Sun and consequently gives us the ability to detect the Moon much closer to the Sun than is the case of visual observation. We first compare the relative brightness of the Moon and the Sun over a range of possible frequencies and find the range 5‐100 GHz to be suitable. The next consideration is the atmospheric absorption/emission due to water vapour and oxygen as a function of frequency. This is particularly important since the relevant observations are near the horizon. We show that a frequency of ∼10 GHz is optimal for this programme. We have designed and constructed a telescope with a full width at half-maximum resolution of 0. 6 and low sidelobes to demonstrate the potential of this approach. At the time of the 2012 May 21 New Moon, the Sun/Moon brightness temperature ratio was 72.7 ± 2.2 in agreement with predictions from the literature when combined with the observed sunspot numbers for the day. The Moon would have been readily detectable at ∼2 ◦ from the Sun. Our observations at 16 h 36 min UTindicated that the Moon would have been at closest approach to the Sun 16 h 25 min earlier; this was the annular solar eclipse of 00 h 00 min UT on 2012 May 21.

The solar F-corona at 2.12 pin: calculations of near-solar dust in comparison to 1991 eclipse observations

Abstract: A comparison of 1991 solar eclipse coronal observations over the range of 3R ○ .-8R ○ . at wavelength 2.12 μm, with model calculations of thermal emission and scattering from interplanetary dust particles (IDPs) is presented. The observed brightness in the ecliptic plane shows a monotonic decrease which can be approximated with a radial power law with exponent 2. No signature in the brightness, due to enhanced dust concentration or emission near the Sun can be detected. The modelling attempts result in an average deviation, relative to the observations, of less than 12%, under reasonable assumptions about the spatial distribution and optical and thermal properties of the IDPs