Perhaps among our ancestors one of the issues that most influenced them to gradually begin to study the Universe, has been the brightness of the celestial bodies. Observing the night sky is a delight, showing us millions of twinkling points of distant light. But the largest nocturnal celestial object of all also appears, that orb that resembles a planet from the terrestrial perspective and that we call the Moon. Today we know that the only object in the Solar System that has its own light is the Sun, but why does the Moon shine if it doesn’t have its own light?
The Moon is the only natural satellite that the Earth has, unlike other neighboring planets that have more than one satellite like Jupiter that has more than 70 of them. But on the terrestrial plane we only enjoy the sight of a moon that we see shining in the night sky on the nights when it is positioned in the appropriate places for its observation.
E Sol is the only object with its own light
Within the Solar System, the only object that has its own light thanks to the explosions of nuclear fusion that are constantly brewing in it, is the Sun. Outside of that, all other bodies, whether they are planets, moons, asteroids or dust, do not shine for yes alone However, a very interesting optical phenomenon happens thanks to which we can see the shining Moon during the night landscape and that is that sunlight is reflected in cosmic bodies.
Despite the fact that during its full phase we see a completely illuminated Moon, the natural satellite only reflects between 3% and 12% of the sunlight it receives. But this percentage is enough to appreciate its beauty to the fullest. And if you are wondering why light is not always reflected in the same way, the answer lies behind the explanation of the lunar phases.
Play of light and shadows
The Earth revolves around the Sun thanks to the translation movement, but in turn the Moon also moves around the Earth. The result of the conjunction of these movements results in a play of light and shadow seen from our perspective. Due to the geoid characteristics of the bodies, sunlight only illuminates 50% of them. That is, it would be impossible for it to be daytime on both sides of the Earth simultaneously. The same happens with the Moon, that wherever it is in its trajectory around us, it will receive the sun’s rays only on half of its surface, the other will be plunged into shadows.
However, the position we have from the planet will determine the way we observe it. When it is positioned behind the planet and it is in its full phase, we only see the half that is fully illuminated. The opposite of when it is placed in front of the planet and that is when the new moons occur. But there are also other phases that we know as waning and waxing that occur when it is aligned at 45º and 180º, with degree 0 being the imaginary line that joins the planet with the Sun.
It might interest you