Imaginez des rochers spatiaux géants filant à travers l'univers, mais au lieu de suivre les règles cosmiques habituelles, ils font leur propre chemin. C'est exactement ce que des scientifiques ont découvert—sept "comètes noires" mystérieuses qui semblent défier les lois du mouvement telles que nous les connaissons. Contrairement aux comètes régulières, celles-ci n'ont pas de queues lumineuses et brillantes, ce qui les rend presque invisibles. Elles se déplacent également de manière imprévisible, comme si quelque chose d'inconnu influençait leurs trajectoires. Certains experts pensent qu'elles pourraient être recouvertes de matériaux étranges qui absorbent la lumière, tandis que d'autres croient à l'œuvre de forces invisibles. Quelle qu'en soit la raison, ces comètes rebelles remettent en question ce que nous pensions savoir sur l'espace ! Animation créée par Sympa.
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Stock de fichiers (photos, vidéos et autres):
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https://www.eastnews.ru
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FunTranscript
00:00You stand next to a huge window of the ground at the ceiling of this wandering space ship that you have called your home for a dozen years, with a few hundred other people.
00:12You observe a fascinating object approaching your ship, asking you if it will end this journey and your life.
00:19It looks like an asteroid but acts like a comet.
00:22Moving as if something was pushing it, could it be an engine created by another space civilization?
00:28Are you doomed or about to come into contact with another kind of intelligence?
00:33Now, let's leave this post-apocalyptic fantasy aside and take a closer look at these space invaders called dark comets.
00:41The most intriguing question is obviously, what made them move?
00:45Most likely, it is gas or material escaping from the surface of these space objects.
00:50Interesting fact, until recently, no one was even sure of their existence.
00:55The first dark asteroid was discovered only a few years ago, and since then, researchers have identified 14, including 7 new discoveries very recently.
01:05The history of dark comets began in 2016, when scientists noticed something strange about an asteroid called 2003RM.
01:17Its orbit was not quite what they expected, it had slightly deviated, and no one could explain this change by the typical behavior of an asteroid,
01:26when they receive small pushes caused by the unequal heating of an asteroid by sunlight.
01:32Instead, the movement suggested that 2003RM could have released material, which is often done by comets.
01:40But there was a hitch, the object did not look like a comet.
01:44There was no tail, no visible gas cloud, it was just a small point of light, like an ordinary asteroid.
01:51At first, scientists thought that 2003RM was just an isolated enigma.
01:56But in 2017, a telescope spotted another strange object, the one from outside our solar system.
02:03It was Oumuamua.
02:05It also looked like an asteroid, but had a trajectory that changed as if gas escaped from it.
02:11The similarities between Oumuamua and 2003RM led researchers to think that there could be more such strange objects in the universe.
02:20In 2023, 7 others had been discovered in our solar system.
02:24These discoveries were enough to give this new type of object the name of dark comet.
02:29Now, scientists have enough data to start noticing patterns, and learn more about their characteristics.
02:37Thus, they identified two main groups of dark comets.
02:41The first group, called external dark comets, is larger, with sizes ranging from hundreds of feet and even more.
02:49They follow long and elliptical orbits, similar to those of traditional comets that come from regions close to Jupiter.
02:56The second group, the internal dark comets, is smaller, usually about ten feet in diameter.
03:03These comets move on almost circular orbits, and remain closer to the Sun, near planets such as Earth, Venus and Mars.
03:12The main question today is, where do dark comets come from?
03:16Can they be the remains of larger bodies that have disintegrated?
03:20These celestial bodies could help us understand the history of the solar system.
03:25And if they had brought the ingredients of life to primitive Earth,
03:29once we have studied dark comets in more depth,
03:33we could determine whether they contain materials such as ice or organic compounds.
03:39Indeed, some researchers are certain that dark comets can contain or could contain ice,
03:45and played an important role in the water supply on Earth.
03:48According to some studies, some asteroids in the asteroid belt,
03:52a region between Mars and Jupiter filled with rocky debris,
03:55could have ice under their surface.
03:58And this ice from the asteroid belt could have traveled to space near Earth.
04:04In other words, it could be a way for water to reach our planet.
04:09So far, no one has claimed that dark comets have definitely brought water to Earth.
04:14But it could be another mechanism for moving ice from one part of the solar system to another.
04:21The study also suggests a connection between dark comets
04:24and a group known as the Jupiter family of comets.
04:28These are comets whose orbits are strongly influenced by Jupiter's gravity,
04:33often attracting them to the Sun.
04:35This connection makes it even more difficult to understand the origin of dark comets and their behavior.
04:41Now, let's take a closer look at the differences between asteroids and comets.
04:46Traditional asteroids are rocky bodies that orbit relatively close to the Sun,
04:51usually inside the ice line.
04:54This region is so close to the Sun that any ice present on the surface of an asteroid
04:59would transform directly from a solid state to a gaseous state,
05:03leaving behind only rock.
05:06Comets, on the other hand, are icy bodies that form further from the Sun.
05:10When they approach the inner solar system,
05:13their ice also begins to go from a solid state to a gaseous state,
05:17creating a visible cloud, called a hair, or a tail, while releasing dust and gas.
05:23Dark comets muddle these definitions.
05:27They appear as rocky objects similar to asteroids without a coma or tail,
05:32but they present a typical behavior of comets,
05:35namely small non-gravitational accelerations.
05:39These accelerations occur when the ice turns into gas,
05:43giving the object a slight impulse.
05:46After analyzing 7 known dark comets,
05:48astronomers estimated that between 0.5% and 60% of all geocruisers
05:54could belong to this mysterious category.
05:57And since dark comets probably come from the asteroid belt,
06:01it is likely that ice exists even in the regions of the belt
06:04previously considered too hot.
06:07Now, objects close to Earth, such as dark comets,
06:10do not remain eternally in the same orbit.
06:13The environment close to Earth is unstable,
06:16and objects generally remain there for about 10 million years.
06:19Since the solar system is over 4.5 billion years old,
06:23this means that new objects close to Earth
06:26must constantly replace those that are lost.
06:29Astronomers have used computer models to simulate the movement of objects
06:33under the influence of non-gravitational accelerations.
06:36They traced the trajectories of these objects over a period of 100,000 years,
06:41and discovered that many of them were in the same regions
06:44where we find dark comets today.
06:47Now, you remember this space rock 2003 RM,
06:51which was the first to be called a dark comet.
06:55Well, it provided a particularly interesting clue.
06:59Its elliptical orbit brings it closer to Earth,
07:01then takes it near Jupiter, before returning to Earth.
07:05This trajectory corresponds to what scientists would expect
07:08from a comet of the Jupiter family,
07:11an object that has probably been deflected towards the interior of its original orbit.
07:16However, most of the other dark comets studied
07:20seem to come from the interior regions of the asteroid belt,
07:23closer to Mars.
07:25Dark comets are often small and spin fast.
07:29Astronomers often describe them as dirty ice cubes.
07:32All this because these objects are a mixture of rock and ice,
07:36and when they cross the ice line, their ice begins to turn into gas.
07:41This process not only causes these small non-gravitational accelerations,
07:45but also increases their rotational speed.
07:48And the faster these objects spin,
07:50the easier they can disintegrate into smaller fragments.
07:54The pieces that detach also contain ice.
07:57And as they spin faster and faster,
08:00they break into even smaller pieces.
08:03This process continues until there are only very small objects left,
08:07spinning rapidly.
08:09This cycle of fragmentation helps explain
08:11why dark comets are often so tiny.
08:14But it could also mean that there are more of them than we currently know.
08:19Research on dark comets offers new perspectives
08:22on the distribution of ice in the solar system
08:25and its potential routes to the environment near Earth.
08:29It also raises intriguing questions.
08:31For example, how much ice remains hidden in the asteroid belt?
08:36Or, have dark comets been able to play a role
08:39in the delivery of water or organic matter to Earth?
08:43One of the most important points is that dark comets
08:46could represent a significant part of geocruiser objects.
08:50If this is true, it could mean that our understanding
08:53of the population of geocruiser objects
08:56and their potential risks for our planet is far from complete.
09:00Processes shaping dark comets,
09:03from sublimation to fragmentation,
09:06could be a major factor in the evolution of ice cores
09:09through the solar system.
09:11Fortunately, nowadays, scientists have the opportunity
09:15to combine advanced modelling with observations,
09:19which could possibly enlighten this class of very unobtrusive objects
09:23and provide clues about the history of water and life on Earth.