Solar eclipse

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

On the response of the ionospheric F region over Indian low‐latitude station Gadanki to the annular solar eclipse of 15 January 2010

Abstract: [1] The response of the ionospheric F region over Indian low-latitude regions to the annular solar eclipse of 15 January 2010 is investigated. The foF2 corresponding to an electron density increase of ∼21% at the F2 peak is seen over Gadanki (13.5°N, 79°E) during the course of the eclipse in comparison with the control day behavior. After the peak phase the foF2 shows a large decrease (∼19%) compared to the mean control day pattern. The total electron content (TEC) at Bangalore (13°N, 78°E) which is located very close to Gadanki is expected to follow a similar pattern of temporal evolution. This TEC shows reduction with respect to control day both at the peak phase (17%) and in the postpeak phase (30%). The enhanced foF2 from the start to the peak phase of the eclipse is attributed to the effect of the weakened equatorial ionization anomaly (EIA). At altitude regions below 270 km, the eclipse induced cutoff of solar insolation results in chemical recombination becoming dominant and thus contributes to the decrease in columnar content in spite of foF2 increase. The post peak phase steep decrease of both foF2 and TEC is attributed to the substantial increase in the poleward meridional winds, the inhibition of the EIA, and persistent depletion in the lower-altitude electron densities. In summary, this study demonstrates the modifications in electrodynamics, recombination, and neutral dynamics acting in concert to produce the observed effects at low latitudes during an eclipse.

Why is the Sun's corona so hot? Views from SOHO, Yohkoh and solar eclipses

Abstract: It has been known for over 50 years that the outer atmosphere of the Sun, the so-called corona, has a temperature of 106 K (~0.1 keV) yet the exact reasons for this are still being debated. The magnetic field that pervades the corona is certainly the source of the heating, but the question is whether the field energy is dissipated via numerous, small, random reconnections (known as `nanoflares', i.e. small energy releases of about 1016 J) or the damping of magnetohydrodynamic (MHD) waves propagating up from the Sun's surface layers (the photosphere). Some new evidence from the SOHO and Yohkoh spacecraft, with instruments on board which image the Sun in the extreme ultraviolet and soft x-rays, are shedding new light on the problem - it appears that the energy spectrum of small flare-like phenomena may be such that nanoflares are sufficiently numerous to supply the corona's energy requirements. However, these new findings do not preclude the possibility of MHD wave motions also supplying significant amounts of energy. Theory suggests very short period (<1 s) MHD waves are implicated in the heating process if so. Searches during total solar eclipses for modulations of the white-light coronal intensity that may result are being made with increasingly sophisticated equipment. Some very fast imaging systems are now available, and a description is given of a charge-coupled device camera experiment conducted successfully during the recent total solar eclipse visible in Europe.