Solar eclipse

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

Ionospheric electron content measurements during a solar eclipse

Abstract: During the total solar eclipse of July 20, 1963, changes in the total electron content of the earth's ionosphere were measured by observing the Faraday rotation of polarization of lunar radio waves. Linearly polarized radio waves were transmitted to the moon from the U.S. Army Research and Development Laboratories at Fort Monmouth, Belmar, New Jersey, on a frequency of 151 Mc/s with 50 kw of power, and from Stanford University in Palo Alto, California, on 50 Mc/s also with 50 kw of power output. Our receivers were located at Sagamore Hill Radio Observatory, Hamilton, Massachusetts. On the 50-Mc/s frequency, a receiver was operated at the transmitting site; thus the Stanford data (Howard, private communication) was subtracted from the Sagamore Hill 50-Mc/s data leaving only the amount of change in total polarization rotation that occurred in the ionosphere above Sagamore Hill. Since there was no receiver in operation at the Fort Monmouth site, only the sum of the total electron content in the ionospheres over Sagamore Hill and Fort Monmouth could be determined from the 150-Mc/s data alone.

Submillimeter observations of the 1991 July 11 total solar eclipse

Abstract: We present observations of the 1991 July 11 total solar eclipse at 850 μm made with the Caltech Submillimeter Observatory (CSO) on Mauna Kea. We find that the 850 μm limb is 3380±140 km above the visible limb. We also find that there is a 10% limb brightening in the outer 7″ of the solar disk, and we measure a central brightness temperature of 6400±700 K. These results require that the upper chromosphere not be in hydrostatic equilibrium, with a higher electron density than is predicted by the standard (VAL) model

Fine Structures in the White-Light Solar Corona at the 2006 Eclipse

Abstract: Observations of the total solar eclipse of 2006 March 29, as it crossed Africa from southwest to northeast into a Greek island and beyond, allowed correlations with near-simultaneous coronal observations from several spacecraft, including SOHO and TRACE. New methods of compositing images allow the recovery of higher resolution (1''-2'') on coronal features than had normally been available in the past, reaching substantially higher resolutions than are currently available from space. We discuss a variety of the new methods and observations, and use them to provide the most detailed portrait possible of the Sun, at least on 2006 March 29.

D-region ionosphere response to the total solar eclipse of 22 July 2009 deduced from ELF-VLF tweek observations in the Indian sector

Abstract: [1] 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.

Latitudinal dependence of the ionospheric response to solar eclipse of 15 January 2010

Abstract: [1] The ionospheric responses to the solar eclipse of 15 January 2010 in the equatorial anomaly region have been investigated by three vertical-incidence and seven oblique-incidence ionosondes arranged along the meridian from geomagnetic latitudes 18°N to 30°N in eastern China. Though the solar eclipse occurred later in the evening, the eclipse effect on electron density and reflection height of ionospheric F2 layer was clearly observed. The study of the eclipse lag (the time lag between the occurrence of the eclipse maximum obscuration and the occurrence of the maximum depletion of foF2) with latitude indicates it increased with F2 layer altitude. Results suggest also that this eclipse enhanced the prereversal enhancement. An unusual peak occurred after the maximum reduction in foF2 and this was observed by all our ionosondes. The following F2 layer plasma density increase was considered to be caused by the increased westward electric field.