Showing papers on "Solar eclipse published in 1980"

Ancient Chinese observations of physical phenomena attending solar eclipses

Abstract: The realization that solar activity probably undergoes changes in qualitative character on time scales greater than the 11 or 22 year cycle but short compared to the duration of recorded history gives renewed importance to historical documents describing the state of solar activity. Modern eclipse observation reveal the presence of solar activity through the appearance of coronal structures and prominences. It has been widely remarked that eclipse records prior to the 18th century are uniformly silent on these conspicuous solar eclipse features, raising the possibility, however unlikely, that a change in solar activity has occurred which rendered them only recently noticeable. We present here material from ancient Chinese sources, primarily astrological, that describe phenomena attending solar eclipses that are almost certainly coronal structures and prominences. Thus, these aspects of the present character of solar activity have apparently occurred at other times in history, if not continuously.

VLA observations of spatial structure in the quiet sun at 6 centimeters, during the 1977 October eclipse

Abstract: Observations of a quiet region on the solar disk were made during the partial solar eclipse of 1977 October 12, using the VLA at 4.9 GHz. Data from 21 baselines were used to make a series of one-dimensional synthesis maps as the Moon de-occulted the field of view. Taking successive differences of the one-dimensional maps and applying a coordinate transformation yielded a two-dimensional map in which the basic resolution was 2''.5 x 12''.7. The map showed that the small-scale structure of the region was dominated by a small number of compact sources, whose mean angular size and peak brightness temperature were in the range 9''--25'' and (6--8) x 10/sup 4/ K, respectively. Although comparison with high-resolution H..cap alpha.. photographs showed no clear correlation with the chromospheric network, at least three of six source positions were consistent with the locations of small bipolar regions. This raises the possibility that the radio sources are associated with X-ray bright points.

Measurements of NO, O3, and temperature at 19.8 km during the total solar eclipse of 26 February 1979

Abstract: Local measurements of stratospheric NO and O3 mixing ratios and air temperature were made during the total solar eclipse of 26 February 1979. The instrumentation was carried aboard a U-2 aircraft flown at an altitude of 19.8 km in the region near 47 deg N, 112 deg W. Eclipse maximum occurred approximately in the middle of the 2-3/4-hr measurement period. The NO mixing ratio was reduced at least a factor of 25 at the maximum of the eclipse. The decrease and recovery of NO during the passage of the Moon's shadow over the measurement region follows approximately the predictions of two independent models. No change was observed in either the O3 mixing ratio or the air temperature that could be attributed to the eclipse.

Solar eclipse predictions

Abstract: A method suitable for intermediate level astronomy courses is presented for the calculations of solar eclipses. The results are surprisingly good considering the simplifications used and the avoidance of spherical trigonometry.

Determination of variations of the solar radius from solar eclipse observations

Abstract: This paper describes the method to determine the solar radius and its variations from observations made during total solar eclipses. In particular, the procedure to correct the spherical moon predictions for the effects of lunar mountains and valleys on the width and location of the path of totality is addressed in detail. The errors affecting this technique are addressed, a summary of the results of its application to three solar eclipses are presented, and the implications of the results on the constancy of the solar constant are described.

Probable detection of climatically significant change of the solar constant

Abstract: It is suggested that the decrease in the solar radius inferred from solar eclipse observations made from 1715 to 1979 reflects a variation of the solar constant that may be of considerable climatic significance. A general, time-averaged relationship between changes in the solar constant and changes in the solar radius is derived based on a model of the contraction and expansion of the convective zone. A preliminary numerical calculation of radius changes due to changes in the mixing length of the solar envelope is presented which indicates that a decrease in solar radius of 0.5 arcsec, as observed in the last 264 years, would correspond to a decrease of 0.7% in the solar constant, a value of large climatic significance. Limitations of the observational method and the numerical approach are pointed out, and required additional theoretical and observational efforts are indicated.

Infrared Thermometer Measurements of the Temperature of the Clouds from the Surface during the 7 March 1970 Total Eclipse

Abstract: An infrared thermometer was used to observe the apparent radiation temperature of the overcast sky during a 15 h period including the total solar eclipse of 7 March 1970 at the Suwannee River State Park, Florida. An effective cloud temperature pulse of 12°C rise and 40 min duration was observed to begin at totality. The pulse is explained as due to cloud formation and consequent enhancement of infrared emission from a lower deck in a two-layer overcast. The apparent radiation temperature change calculated from a synthetic sounding constructed for the atmosphere above the site is in good agreement with the observations. Correspondence of the temperature pulse with a pressure pulse of similar character observed nearby by Anderson et al. and a Lamb wave theory by Chimonas to explain the pressure change are discussed.

Phase and field measurements at VLF, LF and HF during the solar eclipse of February 16, 1980 - preliminary results

Abstract: Phase and field measurements at 16kHz (VLF) by monitoring GBR (Rugby, England) and at 10 MHz (HF) ATA (New Delhi) were carried out from Satellite Tracking and Ranging Station (Kavalur) during the solar eclipse of February 16, 1980. In addition, the field strength measurements at 164 kHz, using transmissions from Radio Tashkent, were recorded at Ahmedabad. This paper gives the preliminary results obtained from the data analyzed so far.

Report from the AGU Spring Meeting: U.S.–Canadian observations on the 1979 solar eclipse

Abstract: A strong, pulsating particle event was in progress at the time of the solar eclipse. As a consequence, eclipse effects in the middle atmosphere were suppressed or masked by particle effects. The particle flux comprised hard and soft spectral components which exhibited marked temporal and spatial variations. As a consequence, data intercomparisons have been difficult. Ionization by solar X rays and extreme ultraviolet (EUV), which are strongly modulated by a solar eclipse, was much less than the ionization produced by particles at altitudes below 95 km. Above 95 km, ionization by solar EUV became increasingly important, although even at the higher altitudes, precipitating particles were sometimes dominant.

Behavioural and tetratogenic effects of solar eclipse.

Abstract: The earliest recorded solar eclipse was on October 22, 2137 BC as mentioned in the Chinese 'Slue Ching'. The Chaldean astronomer in about 400 BC discovered that eclipses occur in regular succession at an interval of about 18 years, the cycle being called the Chaldean Saros. The exact interval is 223 lunatians or 6585.3 days. Out of a total of 65 eclipses in 19th century only 4 total solar eclipses were seen over India, i.e. on December 21, 1843, August 18, 1868, December 12, 1871 and January 22, 1998. The first one passed over South India, the second over Masulipatnam, the third across the Madras Presidency and the last over Central India. Prior to the eclipse of February 16, 1980, there were sixty total solar eclipses during the present century, of which 3 were visible in India. The present one (Feb. 16, 1980) was observed between 2.00-5.00 p.m. in different parts of India. Here at Lucknow, where the work has been carried out, it began at 2.39 p.m. reached its greatest phase at 3.51 p.m. and deeclipsed at 4.55 p.m. It covered 70% of the sun's surface.

Speckle Interferometric Techniques Applied To The Observation Of The Solar Photosphere

Abstract: Speckle interferometric techniques are used to study the solar granulation. Calibration of the effects of atmospheric turbulence is performed by using either the difference in behaviour between redundant and non redundant apertures in presence of atmospheric turbulence, or by analysing moon-limb blurring during a solar eclipse, or by using the changes in seeing conditions during speckle-interferometric measurements. These techniques require a theoreti-cal knowledge of the effects of atmospheric turbulence on the modulation transfer function (M.T.F.) of the image as it is impratical to use an unresolved star near the sun as a reference source during day time observations. The agreement between the experimental M.T.F. obtained with an unresolved star and the theoretical form deduced from Korff's log-normal assumptions is extended to day time conditions.© (1980) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Atmospheric boundary layer processes during a total solar eclipse

Abstract: The total solar eclipse that occurred over the southern part of India on February 16, 1980, gave a unique opportunity to study the earth's atmospheric boundary layer. The meteorological experiments during the 1980 solar eclipse were conducted at Raichur, India (16/sup 0/12'N, 77/sup 0/21'E) located in the state of Karnataka, approximately 400-m above sea level. The main objective was to determine the changes in the earth's atmosphere during and immediately after the eclipse. The goal was to study the changes in the momentum and heat fluxes in the boundary layer due to the eclipse. Measurements were made for 2 days prior to and 1 day after the day of the eclipse to determine background characteristics of the boundary layer which might be site-dependent.

On the effect of the partial solar eclipse of 29 April 1976 on electron content

Abstract: Faraday rotation measurements made at a chain of stations and group delay measurements made at Ootacamund from ATS-6 are examined for the partial solar eclipse event of 29 April 1976 There is no evidence of eclipse-induced gravity waves in these measurements extending from Ootacamund near dip equator to Patiala (dip 45° N) Eclipse-induced fluctuations were however reported at Trivandrum, about 300 km south of Ootacamund