RELAZIONI E FUNZIONI PRACTICE WITH CLIL The solar system Knowing that the distance between the Earth and the Moon is, on average, 384,000 km may not tell us much, for the simple reason that we are used to thinking in terms of kilometers; 384,000, although related to a long distance, we do not see it as a particularly large number. Written in scientific notation, it is expressed as 3.84 105 km and, although the exponent that is the order of magnitude is 5, we still struggle to evaluate its scale. It would not get any better with the distance between the other planets. Let us imagine we want to represent, with the relative distances to scale, all the celestial bodies of the Solar System; we could do it up to Mars but, beyond the asteroid belt, it would be too great a distance between one planet and another. The problem could be solved by increasing the scale, but doing so, we should draw Mercury almost over the Sun, as you can easily see in the figure. Mercury Venus Earth Asteroid Belt Mars Jupiter Saturn 0 AU 1.5E8 km 10 AU Uranus 20 AU Neptune 30 AU Pluto 40 AU 5.89E9 km So, to be able to represent the entire Solar System, it is necessary to abandon the idea of a linear scale and adopt that of the logarithmic scale; in this way we obtain an image that contains all planets as well as providing information on real distances. @NASA Exercise Using the two figures shown in the text, calculate approximately the distance of each planet from the Sun. (1 AU - Astronomical Unit is equal to the average distance between the Sun and the Earth, that is about 140 million kilometres). 314