**6. Conclusions**

*Thermodynamics and Energy Engineering*

sphere with the Sun in the center; SS [m2

intensity of the solar radiation is calculated.

 [m2 ]. Replacing it in the previous relationship, we obtain:

atmosphere is referred to as the solar constant [31].

adopted by the World Radiation Center, of 1367 W/m2

(P = 38.34·1025 W) can be calculated with the relation:

with the Sun in the center.

where IS [W/m2

with the relation:

1.496·1011 m:

**Value [W/m2**

where SS = 4·π·D2

IS = 38.34 · 1025/

over time, as can be seen in **Table 1**.

*Accepted values over time for the solar constant.*

the thermal power of the solar radiation is evenly distributed on spherical surfaces,

On these considerations, the thermal power of the radiation emitted by the Sun

By using the relation presented above, the intensity of the solar radiation related to the surface unit of a sphere having the Sun in the center (IS) can be calculated

IS = P/ SS [W/ m2

Thus, the intensity of the available solar radiation at the upper limit of the Earth's atmosphere can be calculated using the previous relation, considering that D is the distance between the Earth and Sun and D = 149,597,871 km = 1.496·108

The intensity of the available solar radiation at the upper limit of the Earth's

The value of the solar constant calculated previously corresponds to the value

by numerous bibliographic sources. The value of the solar constant, which is determined by measurements undertaken by satellites, underwent several corrections

The value of the available solar radiation at the upper limit of the terrestrial atmosphere suffers throughout the year small variations of approx. ± 3%, mainly

1323 1940 Moon [32] 1355 1952 Aldrich and Hoover [33] 1396 1954 Johnson [31] 1353 ± 1.5% 1971 NASA [34] 1373 ± 2% 1977 Frohlich [35] 1368 1981 Willson [36] 1367–1374 1982 Duncan et al. [37] 1367 ± 1% — World Radiation Center [24]

**] Year Author Ref.**

due to fluctuations in the distance between the Earth and the Sun [24].

IS = P/

P = IS · SS [W]. (8)

] is the surface of the sphere on which the

(4 · π · D2). (10)

]. (9)

km =

. (11)

. This value is also reported

] is the intensity of radiation available on the surface unit of a

(4 · π · 1.1496<sup>2</sup> · 1011·2) = 1.364 · 10<sup>3</sup> W/ m<sup>2</sup>

**74**

**Table 1.**

Even if nuclear and solar energies seem to be different domains, the study proved that fission, fusion, and solar energy can be connected and have in common the famous equation of Einstein (E = m·c2 ).

Both in fission and fusion, the mass varies during the reactions, and it was highlighted that the mass variation and the released energy are related by the equation of Einstein.

The same equation was also applied to the mass flow of solar substance that is continuously consumed in the solar fusion reactions, and starting from this point, it was possible to calculate important parameters such as the energy and the power emitted by the sun.

Following this new approach, it was possible to determine the temperature of the sun's surface and the solar constant, both being in agreement with the values provided in literature.

It can be concluded that fission, fusion, and solar energy are linked together by the equation of Einstein.
