Eclipse Of May Research Articles

WANDERINGS OF THE 'SIMPLY PERFECT' BURNHAM TELESCOPE

S.W. Burnham's 6-inch Clark refractor, in service from 1870, quickly became famous as a potent double star catcher. It was the instrument he used for the site survey of Lick Observatory in 1879. Sold to Washburn Observatory, it travelled to Caroline Island with Edward Holden to search for Vulcan during the total solar eclipse of May 1883. Back in Madison, it was used by George Comstock for his measurements of refraction and aberration. In the late 1950s it was used at the Knuijt Observatory in Appleton, Wisconsin. Travels and transformations of this famous telescope have spread its parts widely as astronomical relics, and it even remains in active service today.

Amazonia Introduced to General Relativity: The May 29, 1919, Solar Eclipse from a North-Brazilian Point of View

In 1919, A. C. D. Crommelin and C. R. Davidson, British astronomers from the Greenwich Observatory in England, passed by Amazonia on their Brazilian journey aiming to measure the bending of stars' light rays during the total solar eclipse of May 29, 1919, and thereby put the theory of general relativity to the test. In the context of Crommelin’s and Davidson’s visit, we discuss how Amazonia was introduced to Einstein’s theory of gravitation, and also the observations and repercussions of the May 29, 1919, solar eclipse in Belem, capital city of the North-Brazilian Para state.

A teoria da relatividade de Einstein apresentada para a Amazônia

Neste artigo tratamos da introdução da teoria da relatividade de Einstein na Amazônia brasileira, o que ocorreu por ocasião da passagem dos cientistas britânicos Andrew C. D. Crommelin e Charles R. Davidson por Belém do Pará, antes e depois das medidas por eles realizadas em Sobral, no Ceará, durante o eclipse total do Sol de 29 de maio de 1919.

ЭФФЕКТЫ СОЛНЕЧНОГО ЗАТМЕНИЯ 20 МАРТА 2015 Г. В ИОНОСФЕРЕ НАД ЕВРОПОЙ: РЕЗУЛЬТАТЫ ИОНОЗОНДОВЫХ НАБЛЮДЕНИЙ

ЭФФЕКТЫ СОЛНЕЧНОГО ЗАТМЕНИЯ 20 МАРТА 2015 Г. В ИОНОСФЕРЕ НАД ЕВРОПОЙ: РЕЗУЛЬТАТЫ ИОНОЗОНДОВЫХ НАБЛЮДЕНИЙ

A flux of EUV emission measured on-board the “CORONAS” artificial satellites near minimum and maximum of the 23rd cycle of solar activity

The paper presents data on ionizing short-wave UV-emission of the Sun in a wave-range λ ⩽ 130 nm measured on-board the CORONAS-I and CORONAS-F satellites. There were obtained absolute values of solar flux emission in the spectrum range λ ⩽ 130 nm and the band near H L α hydrogen line on-board both satellites. Measurements on-board the CORONAS-I satellite coincided with a phase near the minimum of solar activity ( F 10.7 = 80–100). In the period from March to June of 1994 the solar flux was equal on the average to 7.5 erg cm −2 s −1 for λ ⩽ 130 nm and the intensity of emission in H L α was equal to (5.5–6.1) erg cm −2 s −1. The measurements on-board the CORONAS-F were performed near the maximum of solar activity ( F 10.7 = 143–279). Emission intensity in H L α line was about 6.8 –8.2 erg cm −2 s −1 and in the wave-range λ ⩽ 130 nm it was equal on the average to 11–13 erg cm −2 s −1. EUV measurements are in agreement with the data obtained on-board UARS satellite and with the results of ionospheric measurement of E-layer critical frequencies. These measurements agree with data of contemporary models as well. A lot of flares including bright ones were observed. The measurement data of a bright flare of X-ray class X5.3 on 25.05.2001 are given. The paper presents the results of comparison between the CORONAS-F data and the X-ray fluxes in waveband 0.1–0.8 nm (GOES). This comparison demonstrated that X-ray emission measured on-board the GOES spacecraft and measured due to SUVR instrument (with filters in wave-range <12 nm) changed almost synchronously in the ranges 0.1–0.8 and 0.1–12 nm. The data measured due to VUSS showed that EUV emission appeared a few minutes (1–13) before X-ray emission. Apparently it evidences that at first a flare begins in the chromosphere and then a heating area is spreading higher. Solar emission increases by ∼20–30% in the range λ < 130 nm, and only by 8–10% in EUV range. Changes of extreme ultraviolet (EUV) solar flux were registered during the annular solar eclipse of May 31, 2003, when the CORONAS-F satellite thrice intersected a zone of the solar eclipse.

Gravitational labs in the sky

Rarely has a single event changed our view of the universe as much as the solar eclipse of May 1919. With the Sun's light blocked by the Moon, Sir Arthur Eddington and colleagues observed that stars close to the Sun appeared to have moved slightly from their usual positions in the sky. This confirmed a prediction of the general theory of relativity – that massive bodies can bend light – which overturned Newton's 200-year-old theory of gravitation and propelled Albert Einstein to global stardom.

An Experimental Gravimetric Result for the Revival of Corpuscular Theory.

The gravitational phenomenon, founded on the assumption of absorption of a flux of gravitons through the matter, led to a law of attraction comprising a term of attenuation of gravity. The attenuation effect, which depends on the distribution of mass elements into the Sun, was compared with the relativistic effect for the orbital elements of planets. The calculations carried out with our modified law of Newton, lead to a perfect agreement for the advance of the perihelion of planets, and give an interaction cross section with the matter of 3.2x10^-17 m2/kg (approximately 10^-40 cm2/nucleon). The effect of attenuation during a solar eclipse will produce a local reduction in the soli-lunar attraction of 0.13 microgal. This small variation of gravity during the eclipse can lead to distortions of the geoid of about ten millimetres of which effect on gravity, estimated at a few microgals, is compatible with the observed gravitational anomalies. The gravimetric measurements taken in the area of Montreal during the Sun eclipse of May 10, 1994, show the existence of an anomaly of 2.4 microgals that coincides perfectly with the period of the eclipse.

Observation of the Annular Solar Eclipse of May 31 2003 in far ultraviolet spectral region

Changes of extreme ultraviolet (EUV) Solar flux were registered during the Annular Solar eclipse of May 31 2003, when CORONAS-F satellite (Oraevsky et al., 2002) intersected thrice a zone of the Solar eclipse. During these periods the solar emission was measured in visible and extreme UV spectral regions (near nm) and the optical (visible) channel of EOS instruments on UTC scale for May 31, 2003 are given on Fig. 1.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Project Halo: The annular solar eclipse of 1994

Solar eclipses are most often described in terms of their astronomical significance, but they also provide a unique opportunity to study various atmospheric phenomena. Because eclipses are brief and usually occur over oceans or remote land surfaces, these opportunities are quite rare. Thus, a comment about the solar eclipse of May 20, 1947, remains as valid today as when it was published nearly half a century ago: “Something also can be learned about how the upper levels of the Earth's own atmosphere are affected by the Sun's rays, by noting what happens in the atmosphere when those rays are cut off during an eclipse” [Colton, 1947].The annular eclipse of May 10, 1994, will provide a significant opportunity for observers in the United States since its centerline will sweep from New Mexico to Maine (Figure 1). I have begun Project Halo to encourage observations of this eclipse, which will be the last visible from the continental United States until 2017.

Effect of solar eclipse on the behavior of a captive group of chimpanzees (Pan troglodytes).

A captive group of chimpanzees, housed in an outdoor compound at the Yerkes Regional Primate Research Center, was observed during the annular solar eclipse of May 30, 1984. The behavior of each animal was recorded using an instantaneous scan-sampling technique (Altmann: Behaviour 49:227-265, 1974). Beginning 2 days prior to the eclipse and continuing through the day following the eclipse, data were collected from 1100 to 1300 hours daily. At 1214 hours on the day of the eclipse, when the sky began to darken and the temperature began to decrease, solitary females and females with infants moved to the top of a climbing structure. As the eclipse progressed, additional chimpanzees began to congregate on the climbing structure and to orient their bodies in the direction of the sun and moon. At 1223 hours, during the period of maximum eclipse, the animals continued to orient their bodies toward the sun and moon and to turn their faces upward. One juvenile stood upright and gestured in the direction of the sun and moon. Sunlight began to increase at 1225 hours, and as it became brighter, the animals began to descend from the climbing structure. The behaviors exhibited by the group during the period of maximum eclipse were not observed prior to or following the eclipse nor as darkness approached at normal, daily sunset. These data indicate that a solar eclipse, a rare and uncommon environmental event, can influence and modulate the behavior of chimpanzees.

Atmospheric hydroxyl response to the partial solar eclipse of May 30, 1984

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.

The visible spectrum of the lower corona during the total eclipse of May 30, 1965

Spectra obtained during the May 30, 1965 eclipse by Dunn aboard the NASA aircraft are presented and analyzed. Equivalent widths and absolute intensities are given for 39 coronal lines between 3300 and 8200 A around the west limb of the Sun at two heights. Details are given on the reduction process, and comparisons are made with other observations from the same eclipse. Some line identifications are discussed.

Ionospheric observations during the annular solar eclipse of 20 May 1966—III Four D-region electron density profiles measured by rocket techniques

Measurements of Faraday rotation and of differential absorption on frequencies 2.2, 3.9 and 7.8 MHz have been used to determine the height distribution of collision frequency and electron concentration during the annular solar eclipse of May 20, 1966 and on a comparison day.

Electron content measurements by beacon S-66 satellite during the May 20, 1966, solar eclipse

During annular solar eclipse of May 20,1966, over the Northern part of Africa and the Southern part of Europe, it was possible for the first time, to investigate the effect of an eclipse on the to tal electron content of the ionosphere, by using the satellite technique. KLOBUCHAR, WHITNEY (1964), HAWARD et al.(1964) also observed the effect of the eclipse on the total electron content by using the moon reflection technique.

Interferometric investigation of the red and green coronal lines during the total solar eclipse of May 30, 1965

Fabry-Perot interferometric observations of the corona were carried out. The 6374 A line shows radial velocities between 10 and 70 km sec-1, both positive and negative. Most profiles of the 6374 A line are not Gaussian. The widths of the lines indicate unacceptably high temperatures, and thus suggest turbulent velocities, which appear to be of the same order as the line displacement velocities. Arguments are put forward that the corona consists mainly of individual non-turbulent knots with relative velocities similar to the measured ones.

Radio observation of the solar eclipse of May 20, 1966

The eclipse of May 20, 1966 was observed at the wavelengths of 3.2 and 9.1 cm by three Arcetri expeditions. The curves obtained by deriving the occultation curves have been filtered by digital techniques to cut off high frequency noise; by them, many characteristics of three sources of the S-component present on the disk have been studied: temperature, dimensions, emitted flux and brightness distribution. Isophotes of the latter are compared with isophotes of the corresponding Hα plages for two sources: a close similarity results for one of them. Moreover it is shown that: (a) the height above the photosphere of the sources at λ = 9.1 cm is greater than that of the sources at λ = 3.2 cm; (b) the maximum of the radio emission is not always placed exactly above a sunspot or above the sunspot group barycentre. Fitting the observed brightness temperatures, as frequency functions, by a power law and using a temperature model of an active region, the electron density distribution can be deduced. The obtained electron density distributions are compared with various models of active regions.

D-region electron density measurements during the solar eclipse of May 20, 1966

Rocket (Underwood and Muney, 1967) and satellite observations of 2–8 Å X-ray emissions indicate that the solar eclipse of May 20, 1966, occurred during a period in which the Sun was moderately active. The Goddard Space Flight Center conducted a series of small sounding rocket experiments to measure the ionospheric D-region electron density profile during successive stages of the eclipse. Compared to the uneclipsed profile, an order of magnitude reduction is observed in the D-region profile obtained near totality. From the electron density measurements together with the X-ray spectral data of Underwood and Muney it is concluded that on May 20, 1966, 2–8 Å X-rays were not the dominant source of D-region ionization below approximately 80 km.

Brightness distribution of soft X-rays on the Sun, inferred from ionospheric E-layer variations during an eclipse

Solar eclipse variations of the E-layer critical frequency at two stations near the central line of the eclipse of May 20, 1966, can be explained by quasi-equilibrium (constant effective recombination coefficient α eff ≧ 8 × 10 −8 cm 3 sec −1 ) between the electron density and the ionizing soft X-ray radiation emitted non-uniformly from the Sun. The ionospheric data are fitted well by a brightness distribution model attributing 27 per cent of the solar emission to the limb corona (including two localized bright parts of the limb), and 70 per cent to a uniform disk radiation, in fair agreement with Elwert's (1958) theoretical estimations for soft X-rays. A source of hard X-ray emission near the central meridian, as found in the SOLRAD-satellite measurements during the eclipse, had only a very small influence on the E-layer variation. This leads to the assumption that the soft X-rays from local sources, in contrast to the hard X-rays, exceed the relatively high uniform-disk background level only when the sources approach the solar limb.

Magnetic-field structure associated with coronal streamers

An interesting coronal structure was observed during the solar eclipse of May 30, 1965. This comprised a series of bright arches centered approximately on a quiescent prominence. A bright ray originated near the top of one of the arches and pointed almost radially away from the photosphere. The ray could be followed for 1.5 solar radii and was deflected towards a direction parallel to the equatorial plane. By comparing the photographs with Fraunhofer maps and magnetograms, the following interpretation of the structure was obtained. The prominence lies above the neutral line of an extended bipolar magnetic region. The bright arches coincide with flux tubes arising from small photospheric regions of enhanced magnetic-field strength. The ray represents a projection view of a thin region of enhanced plasma density in the neighborhood of a current sheet which separates two flux tubes of opposite polarity. The ray is interpreted as a coronal streamer, and it is suggested that all streamers are related to current sheets.

The ozone variations during the solar eclipse of 20 May 1966

During the annular (87.6%) solar eclipse of May 20, 1966, more than 60 measurements of total ozone were taken with the Dobson ozonespectrophotometer at the University of Sofia, Bulgaria. An analysis of data obtained shows an ozone increase of 25–30 m atm-cm (?? > 2??) at the maximum phase of the eclipse. However, according to the photochemical theory, only ?1 m atm-cm increase should occur during an eclipse such as this. The difference between the theoretical and observed increase of the total ozone may be partly due to the limb-darkening effect. The importance of this effect increases progressively to the maximum phase of the eclipse. When dark-limb correction is applied to observational data, the ozone increase is reduced to 14 m atm-cm (about 4 per cent of the total ozone amount). This increase is as yet unexplained. DOI: 10.1111/j.2153-3490.1968.tb00382.x