Perhaps among our ancestors, one of the issues that most influenced them to gradually begin to study the Universe was the brightness of the celestial bodies. Observing the night sky is a delight that shows us millions of twinkling points of distant lights. 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 that has its own light in the Solar System is the Sun, but then, why does the Moon shine if it does not have its own light?
The Moon is the only natural satellite that the Earth has, unlike other neighbors that have more than one satellite, such as Jupiter, which has more than 70 of them. But on the terrestrial plane we only enjoy the view of a moon that we see shining in the night sky on the nights when it is positioned in the appropriate places for observation.
The Sun is the only object with its own light
Within the Solar System, the only object that has its own light thanks to the nuclear fusion explosions that constantly take place in it, is the Sun. Outside of that, all other bodies, whether planets, moons, asteroids or dust, do not shine brightly. yes alone. However, a very interesting optical phenomenon happens thanks to which we can see the glowing Moon during the night landscape and that is that sunlight is reflected by cosmic bodies.
Although 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 its maximum splendor. And if you’re wondering why light doesn’t always reflect in the same way, the answer lies behind the explanation of moon phases.
Play of light and shadows
around the Sun thanks to translational movement, but at the same time the Moon also moves around the Earth. The result of the conjunction of these movements results in a play of lights and shadows 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 thing happens with the Moon, that wherever it is in its path 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 is in its full phase, we only see the half that is completely illuminated. Contrary to when it is placed in front of the planet and that is when new moons occur. But there are also other phases that we know as waning and waxing that occur when it aligns at 45º and 180º, with degree 0 being the imaginary line that unites the planet with the Sun.