Dans l'espace, des directions comme « en haut » et « en bas » n'existent pas vraiment de la même manière qu'elles le font sur Terre. Puisqu'il n'y a pas de gravité pour tout attirer vers un même point, il n'y a pas de sens de direction fixe. Les astronautes et les engins spatiaux s'appuient plutôt sur la position des étoiles et des planètes pour naviguer. Les agences spatiales comme la NASA utilisent souvent des termes comme « au-dessus » ou « en dessous » par rapport à l'orientation de la Terre, mais tout est relatif parce que tout flotte ! Même lorsque nous utilisons des termes comme « nord » ou « sud » dans l'espace, c'est basé sur les pôles de la Terre, pas un véritable guide universel. Ainsi, dans l'immensité de l'espace, les directions concernent davantage la position des choses les unes par rapport aux autres plutôt que la manière dont nous les concevons ici sur Terre. Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/ Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ---------------------------------------------------------------------------------------- Si tu en veux encore plus, fais un tour ici: http://sympa-sympa.com
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00:00Imagine yourself floating in the infinite immensity of space.
00:04There is no edge, no corner, no top, no bottom, no left, no right.
00:08It's as if you were lost in a galactic desert.
00:11Except that, to guide you, you cannot rely on any natural reference point,
00:16not even on your usual sense of direction.
00:19And without gravity, you could even find yourself making turns in all directions,
00:24as if you were caught in a celestial skydive.
00:27So, what to do?
00:29How to know where to go? How to avoid getting lost?
00:32The question is not simple.
00:34First of all, let's go back to our good old planet Earth,
00:37where orientation is something that we often take for granted.
00:41Imagine that you are hiking in a dense forest.
00:44You are surrounded by gigantic trees, mossy rocks, and birds chirping.
00:49But there is neither a well-defined path, nor a signpost to guide you.
00:53What should you do?
00:55The first thing that comes to mind is a compass, isn't it?
00:58A little magic device that always knows how to find the North,
01:01wherever you are on the planet.
01:04And this, thanks to a very small magnet.
01:07It reacts to the attraction of the Earth's magnetic field,
01:10which covers our planet like a blanket.
01:13This field draws its arrow to the north pole of the planet.
01:16Once you know where the North is,
01:18you know where the East, West and South are.
01:21And now, you can orient yourself in nature like a chevronned explorer.
01:26This is what we call a reference point.
01:29But it's not just forests.
01:31Think of the reference points that you use in your daily life.
01:35When you follow the indications on a map,
01:37consult your GPS navigation system,
01:40or simply when you tell someone the direction to take at the corner of a street.
01:44And in the air, we use water.
01:49Imagine that you are embarking on an exciting adventure in Montgolfière.
01:53As you climb,
01:55you discover wavy landscapes and sparkling oceans.
01:58It's breathtaking.
02:00But how do you know how high you are?
02:03Well, that's where the sea level comes into play.
02:06You have probably already heard the expressions
02:09above the sea level,
02:11or below the sea level in your daily life.
02:14This is the average level of the oceans on the planet.
02:18A universal reference that serves as a starting point
02:21for measuring heights and depths.
02:24When you climb in your Montgolfière,
02:27you can use, for example, an altimeter
02:30to measure your altitude in relation to the sea level.
02:33This instrument tells you how far you have climbed in the sky.
02:37And it's not just useful for adventures in Montgolfière.
02:41We calculate the altitude in relation to the sea level
02:44in many areas,
02:46from aviation to meteorology,
02:48through geography.
02:50It helps us to know the height of the mountains,
02:52the depth of the oceans,
02:54the altitude of cities,
02:56and even the flight trajectories of airplanes.
02:58We have reference points all around us on Earth.
03:01But when we take altitude,
03:03all this becomes much more complicated.
03:06In space, there are no natural landmarks,
03:09no compass, no universal altimeter.
03:12And in the absence of fixed reference points,
03:15determining the orientation is a real challenge.
03:18Even the stars, which are often used for navigation on Earth,
03:22can be misleading in space.
03:24On Earth, the stars seem to move
03:27according to a fixed diagram due to the rotation of our planet.
03:31But in space, they seem to move
03:33and change position as you travel.
03:37So what should we do?
03:39A point technology and precise calculations are necessary.
03:42Our intrepid ships have ingenious solutions
03:45to navigate in the seas of the galaxy.
03:48One of the most amazing tools
03:50used by space ships for navigation
03:52is the star tracking system.
03:54It's a bit like a cosmic GPS.
03:56Cameras scan the night sky,
03:59draw up a map of the stars,
04:01and use it as a reference point.
04:03Just as we use signaling panels
04:06to find our way to a new city,
04:08our ships use the position of the stars
04:11to determine their orientation and direction in space.
04:15Other celestial objects can also be used
04:18to locate themselves in space,
04:20like planets, moons, and even asteroids.
04:24All this allows us to determine our position
04:26and the direction to take.
04:28We can establish our trajectory
04:30on the basis of these data,
04:32for example, to go from Mercury to Mars,
04:34passing through Venus.
04:35It's like a game of points to connect,
04:37but with planets and moons.
04:39But it's not just about finding your way.
04:42Spacecraft also use these navigation methods
04:46to perform precise maneuvers,
04:48like orbiting around a planet
04:50or landing on a moon.
04:52They use complex calculations
04:54and precise measurements
04:56to determine their altitude, speed,
04:58and trajectory
05:00by using the position of celestial objects
05:02like a compass.
05:04It's like a dance in which the ship
05:06follows directions to perform movements
05:08in the vastness of space.
05:10The gyroscope is another ingenious gadget.
05:13It's a kind of space compass.
05:15Gyroscopes are incredibly sensitive.
05:18They can detect the slightest change in orientation.
05:21They help spacecraft to remain stable
05:24and keep them on the right track.
05:26Our ships also use cameras and lasers
05:29to record images
05:31and measure the distance between objects
05:33such as planets, moons, or asteroids.
05:37And let's not forget all the sophisticated software and algorithms.
05:41Inside each spacecraft
05:43is a brilliant computer brain
05:45that solves complex equations
05:47and calculates trajectories.
05:49But we've only talked about orientation.
05:51What about altitude?
05:53In space, altitude has a different meaning.
05:56It's like trying to measure the height of a skyscraper
05:59without a roof.
06:01This cosmic riddle requires creativity at all costs.
06:05In general, we measure it
06:07with respect to the position of a spaceship or a satellite.
06:10If you're floating near a moon or another celestial body
06:13and you want to know what altitude you're at,
06:15you have to measure the distance
06:17that separates you from the surface of that body.
06:19For example,
06:21astronauts from the International Space Station
06:23calculate their altitude
06:25by referring to the distance that separates them
06:27from the surface of the Earth
06:29far in our atmosphere.
06:31And if the star has no solid surface,
06:33like Jupiter,
06:35which is just a huge ball of gas,
06:37well, all you have to do is pray.
06:39Another method
06:41is to measure the altitude
06:43with respect to the orbit of the spaceship.
06:45You can measure the distance
06:47that separates you from the center
06:49or the plane of your orbit
06:51and use it as a reference point.
06:53These methods may seem complex,
06:55but they are the simplest way
06:57to navigate and maneuver in space.
06:59They allow spacecraft
07:01to accurately control their altitude,
07:03their speed and their trajectory.
07:05Thanks to these methods,
07:07it is possible to perform maneuvers
07:09such as mooring, landing
07:11or synchronization.
07:13Space agencies and missions
07:15also play the role of controllers
07:17of interstellar traffic.
07:19They must ensure that the ships
07:21of different nations and organizations
07:23do not crash into each other.
07:25To organize all this,
07:27they use standardized systems and protocols.
07:29Just as we use signposts
07:31and a road code
07:33to travel on Earth.
07:35In addition to normalized systems,
07:37space agencies and missions
07:39use a code to determine
07:41the direction and orientation in space.
07:43For example, the rule of the right hand.
07:45It is a kind of secret hand
07:47that allows you to understand
07:49in what sense things are
07:51in the fields of physics and engineering.
07:53Imagine that you have
07:55a magic glove capable of
07:57telling you the direction
07:59things will take in certain situations.
08:01Suppose this glove is
08:03on your right hand.
08:05Now, raise your thumb.
08:07It represents the direction
08:09of the force, the thrust
08:11or the traction of an object.
08:13Then, wrap your fingers around
08:15your thumb as if you were closing the fist.
08:17Your fingers now represent
08:19the direction of a magnetic field
08:21or the object in question.
08:23And now, the grand finale.
08:25Point your index finger straight
08:27as if you were pulling a laser beam.
08:29Your index finger now represents
08:31the direction of a movement or a current.
08:33And that's it.
08:35The rule of the right hand
08:37is to use your magic glove
08:39to make the link between the direction
08:41of the force, the thrust,
08:43the magnetic field or the rotation,
08:45fingers, and the movement
08:47or the flow of current, index.
08:49It's a fun and practical trick
08:51that helps scientists
08:53to solve complex problems
08:55in physics and engineering.
08:57Space exploration is a field
08:59that questions our perception
09:01of direction and orientation
09:03and makes us realize
09:05how much we depend on our planet.
09:07Who knows what other madness
09:09awaits us in the future?
09:11For example, quantum navigation
09:13or when we create
09:15distortion speeds like in Star Trek.
09:17These are not only practical
09:19but also very impressive methods.
09:21I can't wait to see them.