Something very strange is happening in the world of Royce, American mercenary rogue. Suddenly and without knowing why, is hurtling into space from a fighter jet. Do not know where or how he got there. Soon, he begins to meet with seven other characters, who have also fallen from the sky in the same unknown landscape, filled with tropical vegetation and sweltering heat and humidity. Little by little they are giving, they all have one thing in common: they are armed to the teeth. Well, and they all speak English, despite being among them a special operations agent, an Israeli soldier, one African and one Russian and a Mexican hit man, a Japanese yakuza, and even a doctor. Tremendously bewildered, undertake the march all together. At first everything seems pretty normal, but soon begin to notice strange effects. Royce realizes that carries compass fails could you be still and draw a fixed point, as usual. In addition, the sun does not appear move across the sky, remaining static. The perplexity of such murderers is perfectly understandable if you think with a little logic and scientific knowledge, skills so little cultivated in our times, especially poor people, very bad. Does a compass crazy and lazy sun are not easy to find near the poles? Oh, sure, but at the poles of peeled cold makes the gonads and these tough guys are in the middle of a jungle, with a heat and Norwegians want for themselves. What's going on, then? Has the climate change has suddenly and caught everyone in their underwear, but with guns very hot? Are they part of a collective nightmare, an experiment or simply, they are all dead and have coincided in hell?
The few lines above are part of the story line of the recent sequel Predators ( Predators , 2010) of one of the most prolific film franchises in recent years. On the screens of all the cinemas of the world have passed the famous and terrifying "predators", members of a cruel and bloodthirsty alien race, from an extremely hot planet and whose ultimate hobby is to hunt down humans or, failing , as the terrible xenomorfos "Aliens" corrosive acid blood, always with the laudable purpose of collecting his bloody spines, uprooted with furious frenzy.
But back to our players where we left off, still shaken by the shock of not knowing where they are. While still walking inside the forest, are suddenly attacked by unknown creatures of extreme ferocity. Your thoughts become even more confusing. Determined to find out what is going on, opt for trying to leave the foliage of the jungle and be given a better position to observe. When you finally reach a promontory his doubts are dispelled at once. Before them, a breathtaking sight and terrible at the same time. His eyes behold the sky astonished. On their heads are several planetary bodies of various sizes. It is obvious that there are on Earth. But then where? And above all, why?
Do not shatter the movie and I will stop right at this very moment. And I do to address an issue that I find very interesting. I am referring to the relative size of the stars when viewed from another celestial body differently. All we have seen many times the Moon and the Sun from the Earth, our planet. Despite that their actual sizes are very different, ye shall have come to realize that, seen from the Earth's surface, their apparent sizes are remarkably similar. With this curious coincidence can enjoy a spectacular eclipses. But why the apparent sizes of the two stars are so similar? I'll tell you in one word: mathematics.
You see, it is an elementary exercise to deduce the expression of apparent diameter of an object to be viewed from a specific distance. Only you have to draw a circle that represents the body observed. Then, from a point outside the circle above (which represents the place of observation) trazáis two lines: a tangent to the circle and the other passing through its center. These two lines, along with the radius of the circle define a triangle. If you remember the concept of tangent of an angle, it is easy to apply to the angle formed by the two straight lines above from the point of observation. This angle is the apparent radius of the star observed, and its tangent is just the ratio of its actual radius and the actual distance separating the two bodies. To have the apparent diameter, simply multiply by two. Simple, is not it?
Well, let us apply now the above expression to the moon and the sun Their respective radii are 1,750 km and 700,000 km, while their distances from Earth are worth 385,000 km and 150,000,000 km, respectively. The calculator tells us that the Moon's apparent diameter as seen from Earth, is 31 minutes of arc, similarly, the Sun reaches 32 minutes. Almost identical!
Moreover, the expression of the angular diameter can also learn how to see the Earth from the lunar surface. To do this you only need to replace the little formula the radius of the Moon by the Earth. The stunt that leaves tells us that Earth's angular diameter is 1 degree with 54 minutes of arc, ie Earth seen from the moon nearly 4 times larger than the Moon from Earth. Is not it great?
is more than obvious that the closer the two stars in question are much larger apparent sizes in the sky. However, there are several difficulties. One has to do with the so-called Roche limit , named after the French mathematician Edouard Roche, who determined theoretically for the first time in 1850. The Roche limit is the minimum distance at which two bodies can be approached without the gravitational tidal forces including fragmented, reducing them to pieces. Never been found in any natural satellite in the solar system whose distance from the home planet is less than the Roche limit. When this happens we find incredible structures such as rings of Saturn, made up of thousands of fragments with a variety of sizes. It is all due to the struggle between two opposing forces: the gravitational force between different parts of the satellite, which tends to hold it together and the gravity exerted by the planet in different ways on different parts of the satellite, depending on their distances from each . Thus, the attraction will be greater on the side closer and much smaller on the face away.
A very simplified calculation, but accurate enough, the value of the Roche limit can be carried out without further that equal the difference between the gravitational forces acting on the two ends of the satellite (the one closest to the planet and far from it) with the gravitational attraction between two pieces of the satellite (each with half of the total mass) separated by a distance equal to the radius of it. Is obtained and an expression that relates the Roche limit to the radius of the planet and the respective densities of both stars.
So, once again, in the case of the Moon Earth and the minimum distance which could reach one another amounts to about 19,000 km. This incredible distance cover the moon in the sky at an angle of 10.5 degrees, ie 21 times larger than now. More spectacular still be contemplating our planet from the surface of the Moon, would spread no less than 37 degrees.
Then, in view of the foregoing, is it reasonable to contemplate the awesome spectacle that our anti-heroes in the game reserve of Predators? Then there is everything, really. First, we do not know if our friends are on a planet and what they see are satellites of the same or vice versa, ie, there is the possibility of staying in a satellite and other satellites are contemplating and / or planets peers, along with the mother planet. To provide a starting point, I will turn to our own solar system (alternative hypotheses can consider yourself as fun). Of the eight known planets, Jupiter is the largest. Of all the satellites, Ganymede is the largest, also belonging to the Jupiter system. Nevertheless, the diameter of Ganymede is just over 5,000 km, less than half the land.
Suppose therefore, that the Predators ferocious sport on field trips on a moon of a Jupiter-like exoplanet unknown, also known as " hot Jupiters" orbiting a star's habitable zone which falls right where the action unfolds. The movements of the actors are quite similar to those that can develop on Earth, which assume that the moon has the same characteristics in terms of size, mass and density as Earth. Using the known values \u200b\u200bsimilar to Jupiter, it is clear that Roche limit should fall around the 112,000 km, measured from the known exoplanet. In this extreme case, the vision of heaven may be shocking, as would cover a region above 65 degrees.
However, not all that easy. Indeed, a body similar to Earth, and located only 112,000 km of a planet like Jupiter would be subject to gravitational forces 340,000 times more intense than those suffered by our own Moon. In fact, the Galilean moons of Jupiter in the flesh experience tremendous tidal forces. Io, the closest of them, for example, suffers a persistent volcanic activity due to the constant action of the giant gravitational presides over its skies. Callisto, on the other hand, is subject to pull over a hundred times greater than that experienced by the moon because the Earth. The world of "Predators", even though at a distance of three times its Roche limit, would be affected by a gravitational force 37,000 times greater than that between the Earth and Moon. Of course, there would be a beautiful sky, a planet occupying more than 24 degrees above the horizon. A spectacular sight, where nobody will pull your spine ...
Sources:
A Simplified Treatment and Simulated Experimental Theoretical Calculation of the Roche Limit . Michael C. Loprest. The Physics Teacher. Vol 44, 381-383. Sept. 2006.
My fucking brain, Sergio L. Palacios (Ph. D.), Journal of Mental intelects Tara and absolutely superior, Vol 69, p. 69-96. November 2010.
0 comments:
Post a Comment