The Sun
The Sun is the closest star, which makes life on Earth possible. The sun is a sphere with a 1.4 million km diameter (109 times as much as the earth’s diameter) and has a mass approximately 300.000 times greater than the earth’s mass. 75% of it is hydrogen, 23% is helium and only 2% is formed by heavier elements. It produces its heat by transforming hydrogen into helium in its inner core, where the temperature reaches 15 million °C (the surface temperature is around 6000°C). The transformation reaction is called nuclear fusion and joins together 4 nuclei of hydrogen (protons) to create a helium nucleus, freeing a large quantity of energy, which, as photons, is irradiated towards the space. A solar constant is the radiation that perpendicularly hits a unit surface positioned at the top limit of the atmosphere and amounts to 1350 watts per square metre. This heat, multiplied by the surface of the earth’s section (the squared earth’s average radius multiplied by pi Greco) calculates the quantity of energy the earth receives from the sun every second, i.e. 173,000 TW.
Special reports
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13 May 2018
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Faraday, an electrifying biography
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Italy’s renewable sources
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18 February 2021
Is lithium the new petroleum?
Today petroleum vies for the title of “contemporary gold” with several competitors, one of those is certainly lithium...
17 March 2020
Energy and renewable sources: what is the current status?
The unstoppable growth of renewable sources continues…
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13 May 2018
Small steps, great footprints
Have you ever wondered how much space is taken up by an apple or a steak?...
-
30 April 2022
Solar energy in Italy: where do we stand?
The Sun is the main source of energy on our planet, from which we derive almost all the forms of…
-
5 September 2021
Faraday, an electrifying biography
"The important thing is to know how to take all things quietly". Michael Faraday...
14 July 2021
Italy’s renewable sources
Renewable energy sources in Italy The Energy Services Operator (GSE) periodically publishes data and statistics on the renewable energy sources…
-
13 May 2018
Small steps, great footprints
Have you ever wondered how much space is taken up by an apple or a steak?...
From the Multimedia section
Facts
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Bio-climatic architecture
Solar energy is playing a vital role with reference to bioclimatic architecture...
The photovoltaic train
In Italy the PVTRAIN project by Trenitalia (co-financed by the European Union) plans...
The plant of Almeria
In the Tabernas desert, 30 km north-east of the Andalusia town of Almeria (Spain)...
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Italian offshore wind farm
The first Italian wind farm will be installed in the waters of the Strait of Otranto...
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An artificial geyser
Electric and thermal power produced from geothermal energy depend on the existence of underground infiltrations...
A hydrogen house
In Settimo, a municipality close to Turin, the first Unité d’Abitation has been created...
Hydrogen from biomass
Hydrogen is an energy carrier that allows to generate energy in an environmentally sustainable way...
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16 May 2011
Bio-climatic architecture
Solar energy is playing a vital role with reference to bioclimatic architecture...
The photovoltaic train
In Italy the PVTRAIN project by Trenitalia (co-financed by the European Union) plans...
-
The plant of Almeria
In the Tabernas desert, 30 km north-east of the Andalusia town of Almeria (Spain)...
-
Italian offshore wind farm
The first Italian wind farm will be installed in the waters of the Strait of Otranto...
-
16 May 2011
Bio-climatic architecture
Solar energy is playing a vital role with reference to bioclimatic architecture...
-
The photovoltaic train
In Italy the PVTRAIN project by Trenitalia (co-financed by the European Union) plans...
-
The plant of Almeria
In the Tabernas desert, 30 km north-east of the Andalusia town of Almeria (Spain)...