Is the interstellar object an extraterrestrial vessel?

From another solar system, the celestial object 'Oumuamua intriguing astronomers. In front of its very unusual form for an asteroid, many wonder if it is not an artificial object of extraterrestrial origin. The program Breakthrough Listen who will sound it on December 13 should be able to answer this question.

Since its discovery on October 19th, 1I / 2017 U1, now known as'Oumuamua ("Messenger coming from far and coming first" in Hawaiian), focuses the attention of astronomers. An understandable curiosity because, by its hyperbolic trajectory and its high speed (314.000 km / h at its maximum), the object was confirmed as being the first ever detected to come from beyond our Solar System.

Qualified tointerstellar asteroid, the celestial body intrigues more than ever since the more precise observations made with the In 1993, the ESO launches the project VLT (Very Large Telescope) and decides to install it on the site of Cerro Parbad, in the Chilean Andes, where the climate is particularly favorable to astronomical observations. It … "data-image =" https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/f/0/7/f073110cb2_50034377_vlt.jpg "data-url =" / sciences / definitions / universe-vlt-2147 / "data-more =" Read more ">VLT suggest that Oumuamua is 10 times longer than broad (about 400 meters), dense and rich in Au contact with an acid, a metal gives a salt; in contact with oxygen, it gives an oxide (with difficulty for "noble metals" such as gold, silver, etc.) "data-url =" / sciences / definitions / matiere-metal-3877 / "data-more = "Read more">metal. Its elongated shape very unusual for a asteroid or a comet surprises and returns to the novel Appointment with Rama Arthur C. Clarke (see article below), in which a cylinder 50 km long is spotted by our radars in 2131. In this case, would it be an alien vessel? And are there pbadengers on board? Its tapered shape is actually the most suitable for interstellar travel, minimizing friction with dust and gases. Even tiny, this possibility is not to be discarded. Also, in doubt, scientists want to check. On the spot ? It would be good but not for now (see Lyra project). It will be remote, to begin with.

Breakthrough Listen will listen to 'Oumuamua

Breakthrough Initiatives as part of the research program of evidence of extraterrestrial civilizations in the history of the universe begins some 13.7 billion years ago in an extremely dense and hot soup. The laws of physics as we … "data-image =" https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/1/5/5/1557798396_80921_univers.jpg " data-url = "/ sciences / definitions / astronomy-universe-15239 /" data-more = "Read more">universe Breakthrough Listen, worn by Youri Milner, has just announced that'Oumuamua will be watched continuously for ten hours through four radio bands (from 1 to 12 Ghz) with the radiotelescope Robert C. Byrd of Greenbank, this Wednesday, December 13th. "We do not want to be sensationalist and we are very realistic about the chances of it being artificial., develops the billionaire. But because it's a unique situation, we believe that humanity can afford 10 hours of observation time by using the best equipment on the planet to test a low probability badumption. "

Distant more than 300 million kilometers from the Earth (32 million on October 14th), or two The Big Bang to the Living Site … "data-image =" https: //fr.cdn.v5.futura-sciences .com / buildsv6 / images / midioriginal / 4 / e / 0 / 4e0655d484_50034138_solarmap.jpg "data-url =" / sciences / definitions / universe-astronomical-unit-63 / "data-more =" Read more ">astronomical units – it's like he's between Mars and Jupiter -, the celestial object continues its ride towards the borders of the Solar System, towards Pegasus. It is at present 70 times closer to our antennas than the probe Parts of the Earth in 1977, the probes … "data-image =" https://fr.cdn.v5.futura-sciences.com /buildsv6/images/midioriginal/d/1/1/d11a7349b1_50034545_voyager-choc-teminal.jpg "data-url =" / sciences / definitions / travel-universe-2-3631 / "data-more =" Read more ">Traveling 1, to this day the farthest of all the terrestrial vessels. "At this distance, it will take less than a minute for the Green Bank instrument to detect an omnidirectional transmitter with the power of a cell phone", indicates the communicated.

Within two days, researchers may be able to declare whether 'Oumuamua is an artifact or not. If so, they say they would not keep the news for them and would share it with other observatories for verification. And if it is not the case – we would like that no – other campaigns are planned later to probe in other parts of For example, an acoustic spectrum represents the intensity … "data -url = "/ sciences / definitions / physics-spectrum-1663 /" data-more = "Read more">spectrum radio, looking for any traces of water vapor or other gas testifying to an old cometary activity. These observations should make it possible to eliminate or not the hypothesis that this object is (or was) a comet. Anyway, says Andrew Siemion, director of Seti Research Center from Berkeley, "Whether this object proves to be artificial or natural, it is an excellent target to listen to".

Would Oumuamua be a busy extraterrestrial ship?

Asked by the magazine Scientific American, astrophysicist Avi Loeb, who insisted on Yuri Milner to continue Oumuamua's observations, said he was pessimistic about the possibility of it being an alien ship. "On the one hand, its estimated turnover rate seems too low to create useful quantities of"severity artificial "for all that is on board." In addition,'Oumuamua shows no sign of movement due to rockets or other technologies, and instead follows an astronomical orbit
In astronomy, the orbit designates the closed trajectory followed by a celestial body around another celestial body periodically, under the influence of the … "data-image =" https: //fr.cdn.v5 .futura-sciences.com / buildsv6 / images / midioriginal / 9/2 / e / 92eefd02ac_49145_iss-earth-sun-nasa-s-marshall-space-flight-center-flickr-cc-nc-20.jpg "data-url = "/ sciences / definitions / universe-orbit-873 /" data-more = "Read more">orbit imposed by the Newton and the gravitational force
It is to Isaac Newton that we owe the first formulation of the gravitational force at the base of … "data-image =" https://fr.cdn.v5.futura-sciences.com/buildsv6 /images/midioriginal/c/4/3/c43043335d_96394_gravitation-terre-lune-newton.jpg "data-url =" / sciences / definitions / physics-gravitation-3573 / "data-more =" Read more ">gravitational force of the Sun »he commented. Its speed appears too slow for an interstellar probe. But, after all, "Maybe extraterrestrials have a mother ship that moves quickly and releases space shuttles that fall freely into the planetary system during a reconnaissance mission? The researcher replies that "in such a case, we could then be able to intercept a communication signal between the different spacecraft ". Really ?

The sequel to the next episode, in a few days.

The interstellar object'Oumuamua resembles the Rama vessel of Arthur Clarke's novel

Article of Laurent Sacco published on November 24, 2017

The asteroid 'Oumuamua intrigues with its elongated form. Too small to be Rama's ship, from Arthur Clarke's novel, could it not be an interstellar spacecraft in our Solar System? This is the question that members of the Seti program seem to have been listening to the traveler with radio telescopes.

For all fans of science fiction, especially those who have turned to science under his influence, the discovery of 'Oumuamua, the asteroid from another planetary system, can only be reminiscent of Arthur Clarke and his famous novel Appointment with Rama. The book puts in scene the discovery, in 2131, by terrestrial radars intended to protect the Earth from NEOs, of a large asteroid whose orbital parameters indicate an origin outside the Solar System.

Called Rama in honor of a god of the Hindu pantheon, the object is revealed to be a gigantic almost perfect cylinder, whose wingspan is about 50 km long by 20 km in diameter. It is therefore unquestionably an artifact of a civilization AND technologically advanced.

`Oumuamua was listened to by Seti with ATA

However, `Oumuamua is unlike any of the asteroids of the Solar System and, for the moment, astrophysicists can not explain its stretched shape which makes it look like a long cylinder about 400 meters long. The object is certainly too small to be a Rama, which Clarke describes as the equivalent of an interstellar arch inspired by the famous space colonies of the physicist Gerard K. O'Neill. But nothing forbids to think that it could be an interstellar probe of von Neumann type for example, or, at the very least, of a machine equipped with a super IA. There is no reason to believe that this probe has temporarily slowed down in the Solar System to study it a little, the Earth in particular, while remaining out of reach of the ships of humanity, for safety.

If that's the case, maybe this machine is trying to make a temporary radio contact with us, much like in another Arthur Clarke novel, Fountains of Paradise, staging such a machine called "the Wanderer of Stars". It will not be surprising to learn that members of the Seti program undertook to listen to Oumuamua withAllen Telescope Array (ATA). This indeed reveals the astronomer Franck Marchis, member of Seti Institute, on his page Facebook professional by referring to a note posted on the site of Centauri Dreams.

We learn that physicist James Benford interviewed the famous Jill Tarter about 'Oumuamua. She told him that the Seti Institute had indeed turned some of his ears towards the asteroid, in this case the ATA but also the Green Bank Telescope in the project context Breakthrough Listen, trying to intercept a signal in the famous band 1.1-1.9 GHz, where is the line to 21 cm of hydrogen : a band that we think is privileged for interstellar communication. Analyzes would still be in progress.

This asteroid from another star has a very strange shape

Article by Xavier Demeersman published on 21/11/2017

In the center of all attention since its discovery, 1I / 2017 U1 (`Oumuamua) is not an asteroid like the others: it comes from elsewhere, interstellar space. By its shape and composition, the interstellar visitor astonishes as much as it impresses the astronomers who make up his portrait with small touches.

Since its discovery on October 19, 1I / 2017 U1 (`Oumuamua), or for shorter 'Oumuamua, made the headlines. Astronomers have given themselves the word and number of telescopes among the most powerful and prestigious on the planet are focused on him. It is a matter of fact, indeed, for the researchers because this object which had pbaded 24 million kilometers from the Earth a few weeks ago, is moving away from us with great strides, at more than 90,000 km / h , towards the interstellar space. He will never come back and even if he looks like a asteroidit has nothing to do with the 750,000 or so we know in our solar system.

Many astronomers are amazed by this visitor from elsewhere. A discovery expected for decades. "For the asteroid research community, [la nouvelle] is as important as the announcement of They propagate at the speed of light by carrying energy. We can compare them … "data-image =" https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/f/4/c/f4c81d66a7_86131_ligo-fusion-trou-noir-ligo -nsf-aurore-simonnet.jpg "data-url =" / sciences / definitions / physics-gravitational-wave-4003 / "data-more =" Read more ">gravitational waves", had declared Joseph Masiero, of the Nasa .

In an article that will appear in Nature, an international team confirms the origin In 1995 was discovered the first extrasolar planet to … "data-url =" / sciences / definitions / univers-extrasolar-2575 / "data-more =" Read more ">extrasolar from Oumuamua – whose name, of course, can be translated as "messenger from far away and arrived first" – and draws the most accurate portrait of it to date. And the least we can say is that the object is really amazing, and some features have nothing to do with what we know in our Solar System.

A strange cigar shaped elongated asteroid

First, there is its form. The researchers who studied the curves of his brightness – among others with the VLT – concluded that the object whose Sidereal rotation period and synodic rotation period
We can distinguish the period of sidereal rotation and the period of synodic rotation. The first one is … "data-image =" https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/9/c/4/9c4eee4d81_79793_periode-rotation.jpg "data-url = "/ sciences / definitions / astronomy-period-rotation-15192 /" data-more = "Read more">rotation periodis 7.34 hours is at least 10 times longer than wide. Its brightness varies by a factor of 10. Measuring between about 400 meters, `Oumuamua is all in length, looking like a pencil, a cigar or an Invented in 1624 by Cornelis Drebbel
Use and description of the submarine
For civilian and military use, it is generally used as a warship or is used for research … "data-image =" https://en.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/ 4 / e / 0 / 4e0f60c480_50037804_usnavyseawolfsubmarine-02.jpg "data-url =" / planet / definitions / oceanography-submarine-11148 / "data-more =" Read more ">submarine . A really unusual form. "We do not see anything like this in our solar system" said lead author of the study, Karen Meech, head of the study at the Institute of Astronomy at the University of Hawaii. "We also found that it was sometimes the color …" data-image = "https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/7/9/ 5 / 7951943cc1_85596_couleur.jpg "data-url =" / sciences / definitions / physics-color-4126 / "data-more =" Read more ">colordark red, similar to objects on the periphery of the Solar System, and completely inert, with no trace of dust detected in its immediate environment. "

First taken for a comet , 1I / 2017 U1 is actually poor in water and ice. It is a dense and rocky celestial body, rather rich in metal, say the authors. Its dark hue – we would see it dark brown – would result "The effects of the Realized in a controlled way, irradiation finds applications in different sectors such as the agro-food industry (sanitation and conservation …" data-url = "/ sciences / definitions / phys-irradiation-2461 / "data-more =" Read more ">irradiation by their energy is typically 1 GeV (the energy that would have an electron accelerated by a voltage … "data-url =" / sciences / definitions / universe-cosmic-ray-2446 / "data-more =" Read more ">cosmic raysover millions of years ", writesESO.

The enigmatic origin of Oumuamua

As for its origins, they are still uncertain. If 'Oumuamua came fromVega star as it was proposed, it would have taken 300,000 years to make the trip, and at this time, the star which, like the Sun, moves in the Galaxy, was not in the same place. For researchers, the strange asteroid is a true wanderer, wandering in the interstellar medium for hundreds of millions of years …

Now more than 200 million kilometers from Earth, 1I / 2017 U1 continues to receive the most attention from astronomers. It is currently in the line of sight of space telescopes Spitzer(infrared ) and Hubble (visible).

"We continue to observe this particular object and hope to determine, with greater precision, its provenance and its future destination within the galaxy., comments Olivier aged 1,500 … "data-image =" https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/e/7/2/e729800477_125697_olivier-arbre.jpg "data -url = "/ planet / definitions / botany-olivier-8064 /" data-more = "Read more">Olivier Hainaut, researcher at ESO. Now that we have discovered the very first interstellar rock, we are preparing to observe more! ". And according to the researchers, there are many.

The interstellar asteroid now has a name

Article by Xavier Demeersman published on November 15, 2017

Astronomers have agreed on the name, accepted by the IAU, of the first interstellar asteroid ever discovered. It comes indeed from elsewhere, from another star, and its astronomical designation, like its nickname, directly refer to it. For researchers, it is only the first we notice, many more are coming. The Union … "data-url =" / sciences / definitions / universe-international-union-astronomical-4530 / "data-more =" Read more ">International Astronomical Union comes, for him, to add a letter to the alphabet of small bodies. After "A" and "C", here is "I".

Because of its proven hyperbolic trajectory (eccentricity1.20), the asteroid of about 400 meters discovered on October 19 when it pbaded 30 million kilometers from the Earth, does not come from our solar system but from another. Which star? Researchers are conducting the survey and some are making progress (see article below).

This is the first time in the history of astronomy that a cosmic object from elsewhere is observed. Taken first for a comet, he was appointed in the early hours C / 2017 U1. " It's for comet , "2017" for the year of course and "U1" in reference to the first body found during the second half of October. Finally, for lack of significant cometary activity, the first interstellar comet became the first interstellar asteroid ever observed: A / 2017 U1.

1I / 2017 U1 ('Oumuamua), the first interstellar asteroid

But the "A" is a bit of a problem because it refers to asteroids of our Solar System … For the discoverers and many astronomers with them, it is time to propose a more suitable nomenclature for this type of object which, undoubtedly, is only the first that we let's notice about thousands more to come. The new generations of telescopes should allow us to discover many more.

By its interstellar nature, the designation 1I / 2017 U1 was therefore submitted to the executive committee of theInternational Astronomical Union (UAI) which accepted quickly. So it's official, this asteroidcome from another star is baptized 1I / 2017 U1 ('Oumuamua),' 1I 'for' first interstellar '. Oumuamua is the nickname given to it by the researchers who operated with the PanStarrs telescope-1 , based at the Haleakala Observatory, who discovered him. A name that means in Hawaiian "Messenger coming from far and coming first" and that suits him very well.

The interstellar asteroid may not be alone

Article by Xavier Demeersman published on November 10, 2017

A / 2017 U1, the first interstellar asteroid discovered now has a name: 1I / 2017 U1 (Oumuamua). All Principle and use of the projector
Inside the projector, the light is concentrated in a determined solid angle … "data-image =" https://www.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/c/4 /f/c4fc497e39_50037560_bundesarchiv-bild-101i-113-0005-33a-2c-nordeuropa-2c-k-c3-bcstenbatterie-2c-scheinwerfer.jpg "data-url =" / home / definitions / home-projector-10867 / " data-more = "Read more">projectors are focused on him, rather the telescopes, as he pbades through our solar system. Researchers think they have found their In an ellipse, a particular point of the semi-major axis: the sum (or the difference) of the distances from any point of an ellipse (or a hyperbola) to the foci is … "data-url =" / sciences / definitions / physics-focus-1015 / "data-more =" Read more ">homeof origin and, according to them, many would follow the same path.

Surprised by the polls of the PanStarr-1 telescopes on October 19th, a few weeks after its pbadage close to the Sun, the object A / 2017 U1 has, by its confirmed hyperbolic trajectory (eccentricity of 1.20), all of an interstellar traveler. Aussitôt la nouvelle connue, des dizaines de télescopes de par le monde, amateurs et professionnels, se sont tournés vers ce visiteur d'un autre monde pour tenter d'en savoir plus sur lui. Il faut dire qu'il est le premier de ce type jamais observé par les astronomes et que ce moment est attendu depuis des décennies !

D'abord pris pour une comète — il fut nommé dans un premier temps C/2017 U1 (C pour comète) —, ce corps céleste d'une taille estimée à 400 m a été requalifié peu après sa découverte en asteroid, à cause de l'absence manifeste de chevelure de gaz et de poussière.

Maintenant, du fait de la nature unique de l'objet, des astronomes proposent de le désigner 1I/2017 U1, « I » pour interstellaire. En tout cas, ses découvreurs basés à l'Haleakala (Hawaï) lui ont trouvé un nom : « Oumuamua ». Le mot hawaïen fait référence à un éclaireur ou un messager. « "Ou"' signifie "vouloir tendre la main" et "mua", avec le second "mua" qui met l'accent, signifie d'abord "en avance de" », indiquent-ils.

Plein d’autres « éjectoïdes » à venir

1I/2017 U1 — ou encore 1I/2017 U1 (Oumuamua) — serait ainsi le premier objet interstellaire découvert par l'humanité. Et selon une étude qui vient d'être déposée sur Arxiv , il faut s'attendre à en découvrir d'autres…, beaucoup d'autres. Surtout à partir de 2022 quand le LSST (Large Synoptic Survey Telescope) entrera en service au Chili. Optimistes quant à leur découverte dans un futur proche, les chercheurs esiiment que « le taux de découverte du LSST des éjectoïdes nous aidera à contraindre la Il s’agit généralement d’une fréquence temporelle f, reliée à la période T (exprimée en s) du phénomène observé par la formule suivante : f = 1/T.
Il est aussi possible de…" data-url="/sciences/definitions/physique-frequence-3940/" data-more="Lire la suite">frequency et les propriétés de systèmes planétaires en formation dans notre voisinage galactique ».

Oui, ils les appellent éjectoïdes. Une désignation qui fait bien sûr allusion à la probable origine de Oumuamua. Selon eux, cet objet a été expulsé du système où il est né et la L'unité de la mbade : le kilogramme
La mbade se représente par le symbole m et, dans…" data-image="https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/8/4/b/84b0382c5e_80528_mbade.jpg" data-url="/sciences/definitions/physique-mbade-15213/" data-more="Lire la suite">mbad ainsi éjectée à chaque formation d'un système planétaire comme le nôtre serait d'environ 20 mbades terrestres. 1I/2017 U1 ne serait donc que le premier d'une grande série…

Les probables origines d’Oumuamua

Quant aux origines d'Oumuamua, trois chercheurs ont déposé un article sur Arxiv qui propose une réponse. L'astéroïde ne viendrait pas de Véga, l'Voici une liste d’objets célestes pouvant être dénommé astre (non…" data-image="https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/6/c/c/6cc6562b02_127395_astre-c-esa-hubble-nasa.jpg" data-url="/sciences/definitions/etoile-astre-851/" data-more="Lire la suite">star le plus brillant de la Ensemble de petits satellites…" data-url="/sciences/definitions/univers-constellation-21/" data-more="Lire la suite">constellation de la Lyre, à 25 années-lumière de nous, comme cela a été supposé préliminairement, mais de l'une des très jeunes étoiles de l'badociation Carina, ou Colombe, située entre 163 et 277 années-lumière de la Terre. Les auteurs se sont plongés dans le catalogue du satellite Gaia(qui suit un milliard d'étoiles) pour inférer les étoiles qui ont des mouvements en accord avec celui A/2017 U1.

Compte tenu de sa nature d'asteroid , les astronomes estiment en outre que l'objet devait être à l'intérieur de la ligne de glace du disque protoplanétairede l'étoile où il s'est formé, il y a quelque 45 millions d'années. Car oui, cela ferait donc une quarantaine de millions d'années qu'il voyage. Et il n'est sans doute pas le seul à venir de là-bas, soulignent-ils.

Enfin, ils ont estimé que la planète responsable de l'éjection de l'objet — et donc d'autres avec lui — est (ou était) soit une superterre , soit une géante gazeuse de 20 à 30 mbades terrestres.

La découverte d'Oumuamua ouvre en tout cas un nouveau chapitre de l'histoire de l'astronomie. Les études sur ce fascinant voyageur se multiplient. Vous n'avez pas fini d'en entendre parler.

Découverte du premier astéroïde interstellaire

Article de Xavier Demeersman publié le 27 octobre 2017

Les premières observations d'un petit corps céleste qui vient d'être découvert suggèrent qu'il vient de l'espace interstellaire. Si cela se confirme, ce serait le premier cas connu d'une comète ou d'un astéroïde venu d'ailleurs. Mais d'où ?

Chaque semaine, de nouvelles comètessont découvertes alors qu'elles s'approchent ou entrent dans le Système solaire interne. Petits corps célestes glacés plus ou moins lumineux, selon l'activité de leur noyau réchauffé par le Soleil, elles ont beaucoup à nous dire sur les origines de notre Système solaire. La plupart viennent des régions les plus éloignées de notre étoile, au-delà de Neptune, à des dizaines ou des centaines de milliards de kilomètres. Certaines déboulent pour la première fois dans la région où gravitent les planètes les plus proches du Soleil (les quatre planètes telluriques). Tandis que d'autres, à courte période, par exemple Halley ou Tchouri , sont des habituées.

Mais le 18 octobre, des astronomes ont repéré dans les sondages réalisés par les télescopes PanStarrs 1installés sur l'Haleakala, à Hawaï, un étrange visiteur à quelque 37 millions de kilomètres du Soleil. D'abord baptisé C/2017 U1, l'objet vient d'être requalifié en A/2017 U1 , suggérant une nature d'astéroïde plutôt que de comète. En tout cas, l'astre paraît très pressé et surtout, et c'est plutôt inhabituel, sa trajectoire montre une extrême excentricité hyperbolique (1,19). Aussi, et si d'autres observations ultérieures le confirment, « cet objet pourrait être le premier cas évident d'une comète interstellaire », a déclaré à Sky&Telescope Gareth Williams, qui codirige le MPC (International Astronomical Union's Minor Planet Center), centre qui engrange les données des petits corps célestes.

« Nous attendons ce jour depuis des décennies, s'est exclamé le directeur de Cneos Paul Chodas. On a longtemps émis l'hypothèse que de tels objets existent — des astéroïdes ou des comètes qui se déplacent entre les étoiles et qui traversent parfois notre Système solaire — mais ceci est la première détection de ce type. Les données aideraient à le confirmer. "

D’où vient cette comète ou cet astéroïde apparemment interstellaire ?

L'astre est très pâle (Dans le cas de la magnitude apparente, celle du Soleil est de -26,7. Celle de la Pleine Lune est de -12,9. Pour les étoiles visibles à l'œil nu, elle est comprise entre -1,5 et 6,5." data-image="https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/c/c/4/cc4de2c532_50034105_sirius-wikipedia-mellostorm.jpg" data-url="/sciences/definitions/univers-magnitude-6/" data-more="Lire la définition">magnitude 20). De premiers calculs basés sur sa luminosité estiment pour l'instant sa taille à moins 400 m (Nasa). Assez petit, il a malgré tout survécu à la Les physiciens qualifient la chaleur d'énergie thermique. Dans le système international, elle se mesure donc en joules (J). La chaleur correspond plus précisément à un transfert…" data-image="https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/7/3/5/735709801b_92578_chaleur.jpg" data-url="/sciences/definitions/physique-chaleur-15898/" data-more="Lire la suite">heat du Soleil lorsqu'il était au plus près de lui, le 9 septembre. C'est une des raisons pour lesquelles les chercheurs s'orientent sur la piste d'un astéroïde plutôt qu'une comète. Le supposé visiteur interstellarfile badez vite, à quelque 25,5 km/s. Si c'est une comète, « elle n'a peut-être pas eu le temps de se réchauffer suffisamment pour se briser », suggère Bill Gray , un dynamicien qui s'intéresse à elle.

A/2017 U1 est pbadé dans le voisinage de la Terre, le 14 octobre dernier, à environ 24 millions de kilomètres. Et nous ne sommes pas prêts de le revoir, car il se dirige vers l'espace interstellaire… Où sera-t-il dans un million d'années ? À une quinzaine d'années-lumière…, et peut-être rendra-t-il visite à d'autres étoiles.

Comète, météorite, astéroïde, étoile filante : quelle est la différence ?

Évidemment, cet astéroïde (ou comète) venu d'ailleurs aurait beaucoup de choses à nous raconter. Cela suscite beaucoup de questions : quelle est sa composition ? est-il similaire à nos astéroïdes ? a-t-il visité d'autres étoiles ? quelle est son étoile d'origine ? etc. Pour l'instant, tout ce que peuvent dire les astronomes qui l'étudient est qu'il vient de la direction de Véga(mais pas exactement), l'étoile la plus brillante de la constellation de la Lyre. « C'est exactement ce qu'on peut attendre[notreSystèmesolairesedéplacedanslaDepuislaTerreonnepeutobserverqu’unecoupetransversale"data-image="https://frcdnv5futura-sciencescom/buildsv6/images/midioriginal/7/7/7/777b761907_120668_voie-lactee-galaxiejpg"data-url="/sciences/definitions/univers-voie-lactee-3729/"data-more="Lirelasuite">[notreSystèmesolairesedéplacedanslaDepuislaTerreonnepeutobserverqu’unecoupetransversale"data-image="https://frcdnv5futura-sciencescom/buildsv6/images/midioriginal/7/7/7/777b761907_120668_voie-lactee-galaxiejpg"data-url="/sciences/definitions/univers-voie-lactee-3729/"data-more="Lirelasuite">[notreSystèmesolairesedéplacedanslaDepuislaTerreonnepeutobserverqu’unecoupetransversale”data-image=”https://frcdnv5futura-sciencescom/buildsv6/images/midioriginal/7/7/7/777b761907_120668_voie-lactee-galaxiejpg”data-url=”/sciences/definitions/univers-voie-lactee-3729/”data-more=”Lirelasuite”>[notreSystèmesolairesedéplacedanslaDepuislaTerreonnepeutobserverqu’unecoupetransversale”data-image=”https://frcdnv5futura-sciencescom/buildsv6/images/midioriginal/7/7/7/777b761907_120668_voie-lactee-galaxiejpg”data-url=”/sciences/definitions/univers-voie-lactee-3729/”data-more=”Lirelasuite”>Voie lactée, en direction des étoiles de la Lyre, On l'utilise pour préciser une information (date, définition d'un mot…), faire un ajout à l'intérieur d'une citation ou d'une interview. Généralement, elle se met à la fin de l'information ajoutée, elle-même entre parenthèses ou…" data-image="https://fr.cdn.v5.futura-sciences.com/buildsv6/images/midioriginal/b/8/f/b8f2267ee2_50037070_article.jpg" data-url="/sciences/definitions/homme-ndlr-10262/" data-more="Lire la suite">NDLR]. Il devrait y avoir davantage de comètes interstellaires venant de la direction vers laquelle le Soleil se dirige », explique Luke Dones, du Southwest Research Institute (SwRI) à Boulder, dans le Colorado.

Dans le pbadé, la seule autre comète soupçonnée de venir d'ailleurs était C/1980 E1 Bowell. Mais son excentricité (1,05) a pu être provoquée en cours de route par son pbadage à 35 millions de kilomètres de Jupiter. Peut-être en a-t-il été de même pour C/2017 U1 ? Les chercheurs ne l'excluent pas. L'enquête est en cours et nous devrions en savoir plus sur son histoire dans les semaines à venir.