scholarly journals IV.—On a method of comparing the light of the sun with that of the fixed stars

1829 ◽  
Vol 119 ◽  
pp. 19-27 ◽  
Keyword(s):  
The Sun ◽  
The Earth ◽  
The Mean

One of the most ingenious contributors to the Transactions of our Society in the last century, the Rev. John Michell, in a paper intituled “An inquiry into the probable parallax and magnitude of fixed stars, &c*.” has proposed it to astronomers, as an object worthy their attention, to determine what propor­tion the light, afforded us separately by each fixed star, bears to the light which we receive from the sun; since, from our inability to measure the annual parallax of those very remote bodies, such a comparison is the best, perhaps the only method within our reach, of obtaining, though not certain, yet pro­bable estimates of their distances; and thus forming reasonable conjectures concerning the extent of the visible universe. In order that we may judge, with the least chance of error, of the mean distance of those stars which are the nearest to the earth, he directs us to compare the light of the brightest stars with that of the sun, and next to calculate how far the sun must be re­moved, to make the light that we should then receive from him, not more than equal to the mean light of the stars chosen for comparison. Mr. Michell made, as he says, some rude experiments for determining the comparative brilliancy of certain principal stars; but has not suggested any con­trivance for comparing a star with the sun. He states, however, so distinctly the great object of such a comparison, and the inferences which an industrious ob­server would thence be entitled to draw, concerning the distances of those stars whose light he might succeed in measuring, that it is surprising that no astrono­mer has been incited by these remarks to devise a method of making the requisite observations, and that now, so many years after Mr. Michell’s suggestion was made public, so much remains to be effected in this branch of photometry.

On an inequality of long period in the motions of the Earth and Venus

1837 ◽  
Vol 3 ◽  
pp. 77-78
Keyword(s):  
Principal Term ◽  
The Sun ◽  
Method Of Calculation ◽  
The Third ◽  
Long Period ◽  
Mean Motion ◽  
The Earth ◽  
The Mean ◽  
The Difference

The author had pointed out, in a paper published in the Philosophical Transactions for 1828, on the corrections of the elements of Delambre’s Solar Tables, that the comparison of the corrections of the epochs of the sun and the sun’s perigee, given by the late observations, with the corrections given by the observations of the last century, appears to indicate the existence of some inequality not included in the arguments of those tables. As it was necessary, therefore, to seek for some inequality of long period, he commenced an examination of the mean motions of the planets, with the view of discovering one whose ratio to the mean motion of the earth could be expressed very nearly by a proportion of which the terms are small. The appearances of Venus are found to recur in very nearly the same order every eight years; some multiple, therefore, of the periodic time of Venus is nearly equal to eight years. It is easily seen that this multiple must be thirteen; and consequently eight times the mean motion of Venus is nearly equal to thirteen times the mean motion of the earth. The difference is about one 240th of the mean annual motion of the earth; and it implies the existence of an inequality of which the period is about 240 years. No term has yet been calculated whose period is so long with respect to the periodic time of the planets disturbed. The value of the principal term, calculated from the theory, was given by the author in a postscript to the paper above referred to. In the present memoir he gives an account of the method of calculation, and includes also other terms which are necessarily connected with the principal inequality. The first part treats of the perturbation of the earth’s longitude and radius victor; the second of the perturbation of the earth in latitude; and the third of the perturbations of Venus depending upon the same arguments.

scholarly journals On the Causes of Palaeoclimatic Variations and of the Ice Ages in Particular

1953 ◽  
Vol 2 (13) ◽  
pp. 213-218
Author(s):  
E. J. Öpik
Keyword(s):  
Nuclear Reactions ◽  
Gas Diffusion ◽  
Seasonal Temperature ◽  
The Sun ◽  
Orbital Elements ◽  
Ice Ages ◽  
Solar Mass ◽  
The Earth ◽  
Change In The Mean ◽  
The Mean

AbstractA method of quantitative climatological analysis is developed by applying the principle of geometric similarity to the convective heat transport, which is assumed to vary with the 1.5 power of temperature difference. The method makes possible the calculation of the change in the mean annual, or seasonal temperature, produced by a variation in insolation, cloudiness, snow cover, etc.It is shown that the variations in the orbital elements of the earth cannot account for the phenomena of the ice ages; the chronology of the Quaternary, based on these variations, has no real foundation.Palaeoclimatic variations are most probably due to variations of solar luminosity. These can be traced to periodical re-adjustments in the interior of the sun, produced by an interplay between nuclear reactions and gas diffusion, repeating themselves after some 250 million years. Complications from the outer envelope of the sun lead to additional fluctuations of a shorter period, of the order of 100,000 years to be identified with the periodical advance and retreat of the glaciers during the Quaternary.Calculations of the variations of luminosity in a star of solar mass substantiate this hypothesis.

scholarly journals I. An account of the Sun's distance from the Earth, deduced from Mr. Short's observations relating to the horizontal parallax of the Sun: In a letter from Peter Daval, Esq; V. P. of R. S. to James Barrow, Esq; V. P. of R. S

1763 ◽  
Vol 53 ◽  
pp. 1-2
Keyword(s):  
The Sun ◽  
The Earth ◽  
The Mean

According to Mr. Short, the mean horizontal parallax of the Sun is 8", 65. Now this parallax is the angle, which the semidiameter of the earth subtends, being seen from the Sun.

scholarly journals On a method of comparing the light of the Sun with that of the fixed stars

1833 ◽  
Vol 2 ◽  
pp. 355-355
Keyword(s):  
Full Moon ◽  
Angular Distance ◽  
The Other ◽  
The Sun ◽  
Proper Distance ◽  
The Earth ◽  
Direct Light ◽  
Glass Bulb ◽  
The Mean ◽  
Made In

In the Philosophical Transactions for the year 1767, a suggestion is thrown out by Mr. Michell, that a comparison between the light received from the sun and any of the fixed stars, might furnish data for estimating their relative distances; but no such direct comparison had been attempted. Dr. Wollaston was led to infer from some observations that he made in the year 1799, that the direct light of the sun is about one million times more intense than that of the full moon, and therefore very many million times greater than that of all the fixed stars taken collectively. In order to compare the light of the sun with that of a star, he took, as an intermediate object of comparison, the light of a candle reflected from a small bulb, about a quarter of an inch in diameter, filled with quicksilver, and seen, by one eye, through a lens of two inches focus, at the same time that the star or the sun’s image, placed at a proper distance, was viewed by the other eye through a telescope. The mean of various trials seemed to show that the light of Sirius is equal to that of the sun seen in a glass bulb one tenth of an inch in diameter, at the distance of 210 feet, or that they are in the proportion of one to ten thousand millions; but as nearly one half of the light is lost by reflection, the real proportion between the light from Sirius and the sun is not greater than that of one to twenty thousand millions. If the annual parallax of Sirius be half a second, corresponding to a distance of 525,481 times that of the sun from the earth, its diameter would be 3⋅7 times that of the sun, and its light 13⋅8 times as great. The distance at which the sun would require to be viewed, so that its brightness might be only equal to that of Sirius, would be 141,421 times its present distance; and if still in the ecliptic, its annual parallax in longitude would be nearly 3″; but if situated at the same angular distance from the ecliptic as Sirius is, it would have an annual parallax, in latitude, of 1″⋅8.

scholarly journals On the Causes of Palaeoclimatic Variations and of the Ice Ages in Particular

1953 ◽  
Vol 2 (13) ◽  
pp. 213-218 ◽  
Author(s):  
E. J. Öpik
Keyword(s):  
Nuclear Reactions ◽  
Gas Diffusion ◽  
Seasonal Temperature ◽  
The Sun ◽  
Orbital Elements ◽  
Ice Ages ◽  
Solar Mass ◽  
The Earth ◽  
Change In The Mean ◽  
The Mean

Abstract A method of quantitative climatological analysis is developed by applying the principle of geometric similarity to the convective heat transport, which is assumed to vary with the 1.5 power of temperature difference. The method makes possible the calculation of the change in the mean annual, or seasonal temperature, produced by a variation in insolation, cloudiness, snow cover, etc. It is shown that the variations in the orbital elements of the earth cannot account for the phenomena of the ice ages; the chronology of the Quaternary, based on these variations, has no real foundation. Palaeoclimatic variations are most probably due to variations of solar luminosity. These can be traced to periodical re-adjustments in the interior of the sun, produced by an interplay between nuclear reactions and gas diffusion, repeating themselves after some 250 million years. Complications from the outer envelope of the sun lead to additional fluctuations of a shorter period, of the order of 100,000 years to be identified with the periodical advance and retreat of the glaciers during the Quaternary. Calculations of the variations of luminosity in a star of solar mass substantiate this hypothesis.

Precambrian glaciations and the evolution of the atmosphere

1994 ◽  
Vol 12 (7) ◽  
pp. 674-682 ◽  
Author(s):  
J. H. Carver ◽  
I. M. Vardavas
Keyword(s):  
Simple Model ◽  
Land Surface ◽  
Life Forms ◽  
The Other ◽  
The Sun ◽  
Before Present ◽  
Early Proterozoic ◽  
Late Proterozoic ◽  
The Earth ◽  
The Mean

Abstract. Precambrian glaciations appear to be confined to two periods, one in the early Proterozoic between 2.5 and 2 Gyears BP (Before Present) and the other in the late Proterozoic between 1 and 0.57 Gyear BP. Possible reasons for these broad features of the Precambrian climate have been investigated using a simple model for the mean surface temperature of the Earth that partially compensates for the evolution of the Sun by variations in the atmospheric CO2 content caused by outgassing, the formation of continents and the weathering of the Earth's land surface. It is shown that the model can explain the main changes in the Precambrian climate if the early Proterozoic glaciations were caused by a major episode of continental land building commencing about 3 Gyears BP while the late Proterozoic glaciations resulted from biologicallyenhanced weathering of the land surface due to the proliferation of life forms in the transition from the Proterozoic to the Phanerozoic that began about 1 Gyear BP.

scholarly journals IV. On an inequality of long period in the motions of the Earth and Venus

1832 ◽  
Vol 122 ◽  
pp. 67-124
Keyword(s):  
The Sun ◽  
Long Period ◽  
Mean Motion ◽  
The Earth ◽  
The Mean

In a paper “On the corrections of the elements of Delambre’s Solar Tables,” published in the Philosophical Transactions for 1828, I stated that the comparison of the corrections in the epochs of the sun and the sun’s perigee given by late observations, with the corrections given by the observations of the last century, appeared to indicate the existence of some inequality not included in the arguments of those Tables. As soon as I had convinced myself of the necessity of seeking for some inequality of long period, I commenced an examination of the mean motions of the planets, with the view of finding one whose ratio to the mean motion of the earth could be expressed very nearly by a proportion whose terms were small: and I did not long seek in vain. It is well known that the appearances of Venus recur in very nearly the same order every eight years: and therefore some multiple of the periodic time of Venus is nearly equal to eight years. It is easily seen that this multiple is thirteen: and consequently eight times the mean motion of Venus is nearly equal to thirteen times the mean motion of the Earth. According to Laplace,(Méc. Cél. liv. vi. chap. 6.) the mean annual motion of Venus is 650 g. 198; that of the Earth 399 g. 993.

scholarly journals On the Fluctuations of the Total Solar Irradiance

1993 ◽  
Vol 157 ◽  
pp. 107-107
Author(s):  
W. Schröder ◽  
H.J. Treder
Keyword(s):  
Solar Irradiance ◽  
Energy Production ◽  
Heat Budget ◽  
Total Solar Irradiance ◽  
The Sun ◽  
Solar Constant ◽  
The Earth ◽  
Major Semi Axis ◽  
Fundamental Quantity ◽  
The Mean

The fundamental quantity for the total solar irradiance is the solar constant J which is determined by the mean Sun-Earth distance and by the energy budget in the interior of the sun. The mean distance is the major semi-axis of the earth orbit and therefore a constant of celestial mechanics. The energy production and transport in the interior of the sun must be constant at least during a Helmholtz-Kelvin period. Actually, the heat budget of the sun is constant during some billion years.

scholarly journals The Radiation Integrator in Vacuo, an Instrument for the study of Radiant Heat received from the Sun

1926 ◽  
Vol 25 (3) ◽  
pp. 285-294 ◽  
Author(s):  
P. A. Buxton
Keyword(s):  
Solar Radiation ◽  
Seasonal Changes ◽  
Radiant Heat ◽  
The Other ◽  
The Sun ◽  
The Earth ◽  
The Mean

The “Radiation Integrator in Vacuo” is an instrument designed by a biologist, to assist in the study of solar radiation, as received on the surface of the earth. The principle of the instrument is that a black bulb in vacuo is exposed to the sun's rays; the bulb, which contains alcohol, is connected to a graduated stem maintained at shade temperature; radiant heat from the sun causes alcohol to distil over the bulb into the stem where its volume is measured. In Samoa the shade temperature is practically constant throughout the year, but one believes on theoretical grounds that more radiation is received from the sun between September and March than at the other season, and that the radiation has two maxima, in October and February. This instrument, which has been observed for 12 months, confirms the expectation. The daily mean distillate, the distillate per hour of sunshine (Campbell Stokes) and the mean distillate for the three hours before noon, all show the same seasonal changes.The instrument has been standardized against Gorczynski's pyrheliometer, so that the readings in c.c. of alcohol can be converted into calories. The instrument is not difficult to make or read, and it can be left in the open in all weathers. It integrates its results and requires to be read once a day in Samoa.

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