In 1942, during World War II, English radio and radar systems were suddenly disturbed by signals which had all the appearances of being mysterious enemy transmissions. For a certain period of time, the secret service worked hard to decipher the signals, but to no avail. Surprisingly, astronomers were the ones to crack the code: the message came from far away - none other than the Sun. But the Earth-Sun relationships are much more complex than we can imagine. For example, without the gravitational attraction of the Sun, our planet, like all the other members of our solar system, would leave its orbit and become lost in space. Without the Sun, the Earth would lose its atmosphere, freeze, and become an icy desert. And yet, the Earth must also, to a certain extent, "protect itself" against the Sun. Life, that without the Sun would be impossible, would be quite short if we were exposed to its direct radiation. Luckily, the Earth has two very efficient shields: the atmosphere and the magnetic field. The atmosphere absorbs a large part of the ultraviolet radiations that would be lethal for many other forms of life. And that portion of the energy not absorbed generates temperature and pressure differences, thanks also to the orbital movements of the planets, which create the wind, clouds and rain. The effect of the Earth's magnetic field also extends to great distances in space, but it works just like the atmosphere: it prevents charged particles coming from the Sun, the "solar wind", from striking the Earth, tranfsorming it into a completely sterile world. The special configuration of the Earth's magnetic field, which is shaped like a funnel at the poles, produces the most spectacular phenomena related to the Sun. In fact, it is only in these two narrow areas that some of the charged particles of the solar wind are able to enter the highest layers of the atmosphere. Here, collisions with the air molecules generate energy and the visible portion appears in the form of fantastic colored and changing patterns: what we call the polar lights. But now it is time to leave our star to begin the long voyage to visit all the planets in our solar system, beginning with the celestial body closest to the Sun, to then take a great leap towards the depths of the cosmos. First stop: Mercury.
In 1942, during World War II, English radio and radar systems were suddenly disturbed by signals which had all the appearances of being mysterious enemy transmissions. For a certain period of time, the secret service worked hard to decipher the signals, but to no avail. Surprisingly, astronomers were the ones to crack the code: the message came from far away - none other than the Sun. But the Earth-Sun relationships are much more complex than we can imagine. For example, without the gravitational attraction of the Sun, our planet, like all the other members of our solar system, would leave its orbit and become lost in space. Without the Sun, the Earth would lose its atmosphere, freeze, and become an icy desert. And yet, the Earth must also, to a certain extent, "protect itself" against the Sun. Life, that without the Sun would be impossible, would be quite short if we were exposed to its direct radiation. Luckily, the Earth has two very efficient shields: the atmosphere and the magnetic field. The atmosphere absorbs a large part of the ultraviolet radiations that would be lethal for many other forms of life. And that portion of the energy not absorbed generates temperature and pressure differences, thanks also to the orbital movements of the planets, which create the wind, clouds and rain. The effect of the Earth's magnetic field also extends to great distances in space, but it works just like the atmosphere: it prevents charged particles coming from the Sun, the "solar wind", from striking the Earth, tranfsorming it into a completely sterile world. The special configuration of the Earth's magnetic field, which is shaped like a funnel at the poles, produces the most spectacular phenomena related to the Sun. In fact, it is only in these two narrow areas that some of the charged particles of the solar wind are able to enter the highest layers of the atmosphere. Here, collisions with the air molecules generate energy and the visible portion appears in the form of fantastic colored and changing patterns: what we call the polar lights. But now it is time to leave our star to begin the long voyage to visit all the planets in our solar system, beginning with the celestial body closest to the Sun, to then take a great leap towards the depths of the cosmos. First stop: Mercury.
