3. Note on Solar Radiation

1888 ◽  
Vol 14 ◽  
pp. 118-121
Author(s):  
John Aitken

In the many theories that have been advanced to explain the comparative constancy of solar radiation in long past ages as evidenced by geological history, it has been generally assumed that the temperature of the sun has not varied much, and to account for its not falling in temperature a number of theories have been advanced, all suggesting different sources from which it may have received the energy which it radiates as heat. Since the chemical theory was shown to be insufficient to account for the vast amount of heat radiated, other theories, such as the meteoric theory and the conservation of energy theory, have been advanced.

1971 ◽  
Vol 12 ◽  
pp. 413-421 ◽  
Author(s):  
B.G. Marsden

There has long been speculation as to whether comets evolve into asteroidal objects. On the one hand, in the original version of the Oort (1950) hypothesis, the cometary cloud was supposed to have formed initially from the same material that produced the minor planets; and an obvious corollary was that the main physical difference between comets and minor planets would be that the latter had long since lost their icy surfaces on account of persistent exposure to strong solar radiation (Öpik, 1963). However, following a suggestion by Kuiper (1951), it is now quite widely believed that, whereas the terrestrial planets and minor planets condensed in the inner regions of the primordial solar nebula, icy objects such as comets would have formed more naturally in the outer parts, perhaps even beyond the orbit of Neptune (Cameron, 1962; Whipple, 1964a). Furthermore, recent studies of the evolution of the short-period comets indicate that it is not possible to produce the observed orbital distribution from the Oort cloud, even when multiple encounters with Jupiter are considered (Havnes, 1970). We must now seriously entertain the possibility that most of the short-period orbits evolved directly from low-inclination, low-eccentricity orbits with perihelia initially in the region between, say, the orbits of Saturn and Neptune, and that these comets have never been in the traditional cloud at great distances from the Sun.


2021 ◽  
Vol 57 (2) ◽  
pp. 279-295
Author(s):  
L. O. Marchi ◽  
D. M. Sanchez ◽  
F. C. F. Venditti ◽  
A. F. B. A. Prado ◽  
A. K. Misra

In this work, we study the effects of solar radiation pressure (SRP) on the problem of changing the orbit of an asteroid to support planetary defense, scientific research, or exploitation of materials. This alternative considers a tethered reflective balloon (or a set of reflective balloons) attached to the asteroid, with a high area-to-mass ratio, to use the SRP to deflect a potentially hazardous asteroid (PHA) or to approximate the target asteroid to Earth. The tether is assumed to be inextensible and massless, and the motion is described only in the orbital plane of the asteroid around the Sun. The model is then used to study the effects that the tether length, the reflectivity coefficient, and the area-to-mass ratio have on the deviation of the trajectory of the asteroid.


Author(s):  
Ojo Samuel ◽  
Alimi Taofeek Ayodele ◽  
Amos Anna Solomon

Mathematical models have been very useful in reducing challenges encountered by researchers due to the inability of having solar radiation data or lack of instrumental sites at every point on the Earth.  This work aimed at investigating the prediction performance of Hargreaves-Samani’s model in estimating global solar radiation (GSR) out of the many other empirical models so far formulated for this purpose. This model basically uses maximum and minimum temperature data and basically used in mid-latitudes. The paper attempts to assess the predictive performance of Hargreaves-Samani’s model in the Savanna region using Yola as a case study. Estimated values of GSR from one month data adopted from the Meteorological station of the Department of Geography, Federal University of Technology, Yola, Nigeria was used for this purpose. Using this model shows a 95% index of agreement (IA) with the observed values; which suggests a good model performance and can also be used in estimating global solar radiation in the Savanna region particularly in areas with little or no such climatic data.


2019 ◽  
Vol 3 (1) ◽  
pp. 29-35
Author(s):  
M Barkah Salim ◽  
Nurlaila Rajabiah

The sun is a source of energy that cannot be used up. Therefore, the utilization of solar energy must be a priority. With the many types of solar panels that have been developed, researchers conducted an analysis of 150 watt monocrystalline solar panels. The purpose of this study is to know the amount of current and voltage produced by solar panels in some conditions of the sky, namely cloudy, bright cloudy, and bright. The research method used was the experiment. From the data that has been obtained, it can be found that the energy produced by solar panels during cloudy ranges from 0.6-0.8 amperes, when it is cloudy, 0.9-1.9 amperes, and when bright 2.0-3.2 amperes. The amount of electrical energy that can be produced is 8%. However, if the sunny state can produce twice that Suggestions for readers are if you want to take data to make sure the solar panels are completely exposed to the sun during data collection and in the open area. Much better if the angle is adjusted in the direction of sunlight.


Concentrating Solar Power (CSP) focuses sunlight in order to use the heat energy of the sun. In a central receiver system configuration, many mirrors (heliostats) individually track the sun and reflect the concentrated solar energy onto a receiver on top of a tower. The receiver contains the working fluid which is heated by the concentrated solar radiation. The useful energy that absorbed by the water flows through the receiver in solar tower plant depending on the angle between the solar rays and the position of heliostat in the region of work. Heliostat will reflect the incident solar radiation in the direction of the receiver founded in the top of the tower, in order to get a maximum incident solar radiation on the heliostat reflection area. Because of the cosine factor loss effect due to the sun position is variable along the day from sunrise to sunset, which must be in a minimum value, therefore an automated tracking system with dual axes as a control system with sensors had been built and used to stay the sunrays incident on the receiver, and enable the heliostat to flow the sun where it was


Solar Energy ◽  
1988 ◽  
Vol 41 (4) ◽  
pp. 371-377 ◽  
Author(s):  
P. Ineichen ◽  
A. Zelenka ◽  
O. Guisan ◽  
A. Razafindraibe
Keyword(s):  

Author(s):  
William Lowrie

Two important physical laws determine the behaviour of the Earth as a planet and the relationship between the Sun and its planets: the law of conservation of energy and the law of conservation of angular momentum. ‘Planet Earth’ explains these laws along with the ‘Big Bang’ theory that describes the formation of the solar system: the Sun; the eight planets divided into the inner, terrestrial planets (Mercury, Venus, the Earth, and Mars) and the outer, giant planets (Jupiter, Saturn, Uranus, and Neptune); and the Trans-Neptunian objects that lie beyond Neptune. Kepler’s laws of planetary motion, the Chandler wobble, the effects of the Moon and Jupiter on the Earth’s rotation, and the Milankovitch cycles of climatic variation are also discussed.


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