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Showing papers on "Solar eclipse published in 1985"


Journal ArticleDOI
01 Jan 1985-Nature
TL;DR: In this article, a ground-level pressure wave was detected at three stations in India and one station in Java, Indonesia during a solar eclipse, with a quasi-period of ∼4 h and a wave velocity of ∼320 m s−1.
Abstract: During a solar eclipse the Moon's shadow moves at supersonic speed through the Earth's atmosphere. Chimonas and Hines1,2 suggested that the resultant cooling of the atmosphere would generate a bow wave of atmospheric gravity waves, which may be detectable as a travelling ionospheric disturbance or as a ground-level atmospheric pressure variation. Although the evidence for gravity waves in the ionosphere from a solar eclipse is still weak, they may have been detected3. Ground-level pressure changes during solar eclipses occur near the region of totality4, but the measured wave velocity and period do not agree with that of the predicted disturbance5,6. We now report the detection of a ground-level pressure wave detected at three stations in India and one station in Java, Indonesia. These data may provide the first direct observation of eclipse generated gravity waves over a very long range. The most distant station in India was 6,600 km from the eclipse centre line. The microbarometer recordings indicate that a wave disturbance was recorded at each station with a quasi-period of ∼4 h and a wave velocity of ∼320 m s−1.

26 citations


Journal ArticleDOI
TL;DR: An eclipse of the Sun by the Moon as seen by the Lageos satellite can affect the orbital semimajor axis at the centimeter level as discussed by the authors, which can generate large enough along-track errors to make it worthwhile to include eclipses in complex orbit determination programs such as GEODYN.
Abstract: An eclipse of the Sun by the Moon as seen by the Lageos satellite can affect the orbital semimajor axis at the centimeter level. The weakened radiation pressure acting on Lageos perturbs the orbit differently from that due to full sunlight. This difference amounted to less than 2 mm in the semimajor axis for 23 of the 30 eclipses Lageos experienced between launch in 1976 and the end of 1983. However, it was 17.6 mm for the eclipses on 28 March 1979 and 11.2 mm for the one on 15 December 1982. Differences such as these generate large enough along-track errors to make it worthwhile to include eclipses in complex orbit determination programs such as GEODYN which integrate the orbit. Eclipses cannot explain the presently unmolded variations in along-track acceleration which have a magnitude of about 3 x 10(-12) ms(-2).

17 citations


Journal Article
TL;DR: In this article, les resultats de la photometrie de la couronne solaire, obtenus durant l'eclipse solaire totale du 31 juillet 1981, are presented.
Abstract: Resultats de la photometrie de la couronne solaire, obtenus durant l'eclipse solaire totale du 31 juillet 1981, ainsi qu'une analyse morphologique

14 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the multislit spectra of the coronal emission line taken at the 1980 eclipse to discuss the relative roles of radiative and collisional excitation mechanisms.
Abstract: The line and continuum intensities deduced from the multislit spectra of the (Fe X) coronal emission line taken at the 1980 eclipse are used to discuss the relative roles of radiative and collisional excitation mechanisms. It is shown that for R/R ⊙ < 1.2, collisional excitation is the predominant mode. Collisional as well as radiative excitation is equally important for 1.2 < R/R ⊙ < 1.4, whereas beyond 1.4 R ⊙ radiative excitation becomes dominant. The line width measurements indicate that a large number of locations have half-widths around 1.3 A. The maximum half-width is reached at ∼ 1.4 R ⊙ with an average value of 1.6 A.

14 citations


Journal ArticleDOI
TL;DR: In this paper, a large amplitude oscillation in the vertical column abundance of atmospheric OH was observed in ground-based spectroscopic absorption measurements from Fritz Peak Observatory, Colorado (105°W, 40°N) during and after the partial solar eclipse of May 30, 1984.
Abstract: A large amplitude oscillation in the vertical column abundance of atmospheric OH has been observed in ground-based spectroscopic absorption measurements from Fritz Peak Observatory, Colorado (105°W, 40°N) during and after the partial solar eclipse of May 30, 1984. An initial OH reduction during the eclipse was followed by an underdamped oscillation having a period of about one hour; the OH abundances returned to normal values two hours after the eclipse termination. This is believed to be the first observation of a "ringing" response of any atmospheric constituent to a solar eclipse.

11 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a polaroid filter oriented in three directions 60 degrees apart to estimate the total intensity, degree of polarization, and direction of the electric vector of the corona.
Abstract: Photographic observations of the corona were made by a Belgian expedition to Kenya during the eclipse of 1980, February 16, using a polaroid filter oriented in three directions 60 ° apart. The preliminary results of the reduced data are presented here; these results consist in the analysis of the three following parameters: total intensity, degree of polarization, direction of the electric vector. The local variation of these parameters reveals, among other features, a deep coronal hole at the south pole and peculiar streamer (P.A. 280 °) associated to a transient, (the so-called ‘tennis racket’) also observed by other teams, and a density enhancement at P.A. 200 °, possibly associated with a transient observed with the K-coronameter of the High Altitude Observatory 12 hr before the eclipse.

7 citations


Journal ArticleDOI
19 Dec 1985-Nature
TL;DR: In this paper, the outer solar corona was observed at an altitude of 30 km using a balloon-borne silicon-intensified (SIT) TV camera during the total solar eclipse on 11 June 1983 in Indonesia.
Abstract: It is very difficult to make optical observations from the Earth where the angular distance from the Sun is greater than 3 R⊙ (where R⊙ is the angular radius of the Sun) because of the large and uncertain correction for sky radiation. To overcome these difficulties, we have now made optical polarization observations at four wavelengths (5,330 A, 5,970 A, 7,200 A, 8,015 A) for the outer solar corona at an altitude of 30 km, using a balloon-borne silicon-intensified (SIT) TV camera during the total solar eclipse on 11 June 1983 in Indonesia. As reported here, a polarization excess at an elongation between 4 and 5 R⊙ (1° and 1.25°) from the Sun in the ecliptic plane was observed at a wavelength of 8,015 A on the two-dimensional frame. This is interpreted as an enhancement of dust grains distributed in a ring around the Sun approximately in the ecliptic plane.

7 citations


Journal Article
TL;DR: In this paper, solar effects on middle-atmosphere electrical parameters, as demonstrated by eclipse-associated responses of conductivity, ion mobility, and charge density, are considered for the total solar eclipses at Red Lake, Ontario, Canada on February 26, 1979 and at San Marco range, Kenya, on February 16, 1980.
Abstract: Solar effects on middle-atmosphere electrical parameters, as demonstrated by eclipse-associated responses of conductivity, ion mobility, and charge density, are considered for the total solar eclipses at Red Lake, Ontario, Canada on February 26, 1979 and at San Marco range, Kenya, on February 16, 1980. Negative-conductivity measurements for the Canadian eclipse and probe-current measurements for the Kenyan eclipse demonstrate a rapid loss of free electrons below 80 km at totality. During the Kenyan eclipse, positive-ion responses were different for each of two distinct ion mobility groups. Between 45 and 60 km, eclipse-related positive-ion responses are associated with the low-mobility ions. It is shown that these ions are lost at totality and that an excess buildup occurs following totality. Above 70 km, positive-ion loss at totality is associated with the more mobile ions and only low-mobility positive ions are measured in this region. The buildup in total ion density following totality is thought to result from a reduction in ion loss associated with weak-electron recovery in the region.

7 citations


Journal ArticleDOI
01 Feb 1985-Nature
TL;DR: In spite of arguments about the astronomical interpretation of ancient eclipse records, one thing is certain this paper, the more that can be found, the more useful they will be, and this is the case even in the case of solar eclipses.
Abstract: In spite of arguments about the astronomical interpretation of ancient eclipse records, one thing is certain — the more that can be found, the more useful they will be.

3 citations





Journal ArticleDOI
TL;DR: In this paper, a photo-polarimetry of the F corona in both visual and near-infrared regions was carried out by a balloon observation of the total solar eclipse on 11 June 1983.



Journal ArticleDOI
TL;DR: In this article, a magnetic loop model for slowly varying radio sources on the Sun based on the gyro-radiation mechanism and the radio data at 20, 32, 82 and 21 cm obtained during the total eclipse of 1980 was constructed.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the effect of solar eclipse on the lower ionosphere and found that radio wave scattering was strengthened by the formation of lower ionospheric field-aligned irregularities in the course of the obscuration of solar local ionization source.

Book ChapterDOI
01 Jan 1985
TL;DR: In this article, during the July 31, 1981 solar eclipse, F-corona interferograms near MgI λ 5184 A were obtained using a Fabry-Perot etalon (FPE) with an FWHM of 0.5 A (corresponding to 30 km/sec).
Abstract: During the July 31, 1981 solar eclipse, F-corona interferograms near MgI λ 5184 A were obtained using a Fabry-Perot etalon (FPE) with an FWHM of 0.5 A (corresponding to 30 km/sec) and an image tube. Radial velocities Vr of the interplanetary dust (i.d.) were measured in different directions.

Book ChapterDOI
01 Jan 1985
TL;DR: In this article, the brightness and polarization distributions in a half area of the 6000A picture were measured using a SIT television camera, with 4 interference filters (5300A, 6000A, 7200A and 8000A) and a 45° -step rotating polarizer.
Abstract: A balloon observation of the F-corona in visual and infrared regions was carried out by Japanese and Indonesian teams at the total solar eclipse on June 11, 1983, in Java, Indonesia. For the visual observation, a SIT television camera, with 4 interference filters (5300A, 6000A, 7200A and 8000A) and a 45° -step rotating polarizer, was used. The camera measured brightness distributions in a sky area of 5°x5° centered at the eclipsed sun at each polarizer position for each filter. In this paper, a part of results, which are the brightness and polarization distributions in a half area of the 6000A picture, is shown.