Showing papers on "Solar eclipse published in 1991"
TL;DR: In this article, the authors describe some of the highlights of incoherent scatter observations made at Jicamarca in the 1960s, including a long series of electron density measurements extending to altitudes as high as 10,000 km.
41 citations
TL;DR: In this article, the effects due to the transit of a solar eclipse through SE Asia on 18 March 1988 have been investigated using ionograms, electron content measurements, magnetograms and microbarograph recordings, provided by a chain of stations situated roughly parallel to the path of totality.
40 citations
TL;DR: In this article, socio-cultural experience as a possible generative cause of alternative conceptions in a group of pupils was investigated in the framework of the natural phenomenon of solar eclipse.
Abstract: Socio‐cultural experience as a possible generative cause of alternative conceptions in a group of pupils is investigated in the framework of the natural phenomenon of solar eclipse. The curriculum significance of the outcomes is discussed.
18 citations
TL;DR: In this article, the extreme solar limb in six far-infrared wavelength bands ranging from 30 to 670 micron using the Kuiper Airborne Observatory during the total eclipse of the sun on 1988 March 18 was observed.
Abstract: Observations were made of the extreme solar limb in six far-infrared wavelength bands ranging from 30 to 670 micron using the Kuiper Airborne Observatory during the total eclipse of the sun on 1988 March 18. By observations of the occultation of the solar limb by the moon, it was possible to obtain a spatial resolution of 0.5 arcsec normal to the limb. The solar limb was found to be extended with respect to the visible limb at all of these wavelengths, with the extension increasing with wavelength. Limb brightening was observed to increase slightly with increasing wavelength, and no sign of a sharp emission spike at the extreme limb was found at any of these wavelengths. The observations can be well fitted by a chromospheric model incorporating cool dense spicules in the lower chromosphere.
15 citations
TL;DR: In this article, an imaging dual-channel Fabry-Perot interferometer was used to obtain line profiles simultaneously in the green and red coronal lines at various positions in the corona.
Abstract: During the total solar eclipse of 11 June, 1983, an imaging dual-channel Fabry-Perot interferometer was used to obtain line profiles simultaneously in the green λ5303 A [Fe xiv] and the red λ6374 A [Fe x] coronal lines at various positions in the corona. Extensive microdensitometry followed by multi-Gaussian curve-fitting analysis has resulted in the determination of coronal temperatures and velocity separations between different pockets of coronal gas in the line of sight over a large extent of the corona. Fewer high temperature zones are to be found in the corona of 1983 compared with our similar green-line measurements of the solar maximum corona of 1980. The data are consistent with a temperature maximum occurring at 1.2 R⊙, as found at the 1980 eclipse, but our new data are insufficient to observe farther out than this radius and so determine the position of a maximum. The velocity field in the corona at the 1983 eclipse is less structured compared with that at the 1980 eclipse and is mainly confined to the zone 20–30km s−1.
14 citations
TL;DR: In this article, the period of a torsion pendulum was measured during the solar eclipse of 22 July 1990 in Finland and the relative change in the pendulum's period associated with the eclipse was found to be less than 4.3
Abstract: During the solar eclipse of 22 July 1990 in Finland the period of a torsion pendulum was measured. In previous experiments of this kind [Phys. Rev. D 3, 823 (1971)] a considerable increase was found in the period of the pendulum during the solar eclipse. In our experiment, however, no significant change in the period was observed. The relative change in the pendulum's period associated with the eclipse was found to be less than 4.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ (90% confidence).
14 citations
Patent•
27 Nov 1991
TL;DR: In this paper, a method for determining when an orbiting satellite is eclipsed from the sun in order to remove control torques to the satellite which compensate for the disturbance of solar pressure on the satellite (10).
Abstract: This invention discloses a method for determining when an orbiting satellite (10) is eclipsed from the sun in order to remove control torques to the satellite (10) which compensate for the disturbance of solar pressure on the satellite (10). A current measuring device (46) measures the current traveling through a particular circuit associated with the satellite (10) which is indicative of the satellite batteries being discharged, as would occur during an eclipse. The measured current is applied to a threshold logic circuit (48) which sends a signal to a control compensator (36) if the measured current exceeds a predetermined threshold level. Consequently, the compensation provided by the control compensator (36) removes the compensation for compensating for solar pressure when the satellite (10) is in an eclipse. In a second implementation, the threshold logic circuit (48) is replaced with a proportionality logic circuit to compensate for the effects of partial eclipses.
13 citations
TL;DR: During the solar eclipse of 22 July 1990 in the city of Bielomorsk of the U.S.R., the torsion pendulum experiment of Saxl and Allen was repeated and the relative change in the pendulum's period associated with the eclipse was found to be less than 5.2 times 10 sup minus 5 (90% confidence).
Abstract: During the solar eclipse of 22 July 1990 in the city of Bielomorsk of the U.S.S.R., we repeated the torsion pendulum experiment of Saxl and Allen, who reported an anomalous period increase during the solar eclipse of 7 March 1970. The relative change in the pendulum's period associated with the eclipse was found to be less than 5.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ (90% confidence).
12 citations
12 citations
TL;DR: The line intensity of the green coronal line and the continuum intensity were derived from the filter and white light photographs of the solar corona obtained during the 1980 total solar eclipse.
Abstract: The line intensity of the green coronal line and the continuum intensity are derived from the filter and white light photographs of the solar corona obtained during the 1980 total solar eclipse. Ratio of the line to continuum intensity is plotted against the radial distance r(=R/R0, R0 is the solar radius), in various position angles . A simple model assuming an electron density dependence of the line and continuum intensities suggests a dominant collisional mechanism for the excitation of the line in the innermost regions (~ 1.4 R0). The measured line to continuum ratio tends to a constant value at different radial distances in different position angles. The constancy of the measured line to continuum ratio indicates significant radiative excitation beyond 1.4 R 0, in some of the position angles.
01 Jan 1991
TL;DR: In this paper, infrared sky maps from IRAS and ZIP lead to the result that the average optical properties of the interplanetary dust change with heliocentric distance, and the present uncertainties in calibration should be resolved by COBE.
Abstract: Thermal emission from interplanetary dust is the main source of diffuse radiation at λ 5–50 μm. Analysis of infrared sky maps from IRAS and ZIP lead to the result that the average optical properties of the dust change with heliocentric distance. The present uncertainties in calibration should be resolved by COBE. Existence of a dust sublimation zone at 4 solar radii awaits confirmation at the next solar eclipse.
Patent•
14 Aug 1991
TL;DR: In this paper, an astronomical phenomena solar eclipse demonstrator for classroom teaching and experiments, comprising a simulating sun (1), simulating moon (2), an observer (3), a display screen (4) for displaying the ground and the shadow region, a seat frame (9), supporting frames (5, 8), etc.
Abstract: The utility model relates to an astronomical phenomena solar eclipse demonstrator for classroom teaching and experiments, comprising a simulating sun (1), a simulating moon (2), an observer (3), a display screen (4) for displaying the ground and the shadow region, a seat frame (9), supporting frames (5, 8), etc. The utility model is characterized in that the observer (3) is provided with a telescopic moving lens tube (10) to adjust the focal length of convex lens (12), and the image of the overall process of solar eclipse can realistically be seen through a ground glass screen (11), and the teaching effect can be raised.
01 Feb 1991
TL;DR: The first annular solar eclipse of the Sun occurred on Saturday, 4 January 1992 and Sunday, 5 January 1992 as mentioned in this paper and was preceded by a partial lunar eclipse on 21 December 1991.
Abstract: : By coincidence, the two central solar eclipses of 1992 share a similar characteristic: both central paths will pass almost entirely over water, except for a very small portion at one end which will pass over land and include a major city. The first of the eclipses, an annular eclipse of the Sun, will occur on Saturday, 4 January 1992 and Sunday, 5 January 1992. It will preceded by an associated partial lunar eclipse on 21 December 1991. The central path of this annular eclipse will include a number of small islands in the Pacific Ocean and end over the Los Angeles, California metropolitan area. At maximum over the central Pacific Ocean, approximately 84.4% of the Sun's disk will be obscured. The maximum duration of annularity will be about 11m 36s. Because the track will cross the Internation Date Line, by local times the eclips will occur on the morning of 5 January at the beginning of the path and occur on the evening of 4 January at the end of the path. This eclipse belongs to saros series number 141. The last preceding eclipse in this series was the annular solar eclipse of 24 December 1973; the next eclipse in series will be the annular solar eclips of 15 January 2010.
TL;DR: An examination of decay and growth rates of electric field near the ground during total solar eclipse of 16 February 1980 was made to study the electrical relaxation time and conductivity at Raichur as discussed by the authors.
Abstract: An examination of decay and growth rates of electric field near the ground during total solar eclipse of 16 February 1980 was made to study the electrical relaxation time and conductivity at Raichur. The Values obtained i.e., 1320 seconds and 67.1163 x 10-16 mhos m-1 of the two parameters were in fair agreement with the reported ones at the rural locations.