Surely more than a movie buff and science fiction fan will have come to mind the image of the monolith of the 2001 film: a space odyssey, which is just about to turn fifty, or the alien ships of the arrival. Nicknamed as’ Oumuamua – its official catalog name is 1l / 2017 U1-, the first asteroid from outside the Solar System detected to date can remember those mysterious objects: narrow and elongated, it has also been compared to a cigar or a pen.
Next, the team led by Karen Meech, from the Institute of Astronomy of Hawaii, analyzed the data gathered by the Very Large Telescope (VLT) of the European Southern Observatory (ESO) and other large telescopes to try to make a portrait-robot of ‘Oumuamua. And the first thing that caught their attention is that its brightness multiplied by ten when it rotated on its axis, every 7.3 hours. This means that the asteroid is ten times longer – about 400 meters, they calculate – how wide.
They have also come to the conclusion that their color is dark red, due to the effects of cosmic rays for millions of years, and that there is not a speck of dust around them. All these features suggest that ‘Oumuamua is very dense, probably with a high content of metal, with no significant trace of water or ice.
But where does it come from? It is not known with certainty. Perhaps it comes from a planetary system of the luminous star Vega, in the constellation of Lyra, although it could very well happen that it has been wandering in the Milky Way for hundreds of millions of years without establishing “fixed residence” around any star in the galaxy until its provisional passage through the Solar System.
The authors of the study will continue to observe ‘Oumuamua in the remainder of the year to answer this and other questions. “Now that we have detected the first interstellar rock, we are ready for the next one!” Says optimist Olivier Hainaut, ESO astronomer. Because, as indicated in the report published in Nature , this finding suggests that estimates of the density of this type of objects may have fallen short , and that, thanks to advances in astronomical observation technology and information processing , the harvest of asteroids and comets coming from outer space will surely increase soon. The discovery of interstellar rock, announced in the journal Nature, actually took place on October 19. That day, the Pan-STARRS 1 telescope, located in Hawaii, captured a faint light signal in the sky that scientists initially took for a conventional asteroid.
But the calculations on its orbit revealed that ‘Oumuamua -‘ the first messenger arriving from afar ‘, in Hawaiian – had not originated in the Solar System, like all other asteroids and comets. And additional observations ruled out comet activity when it passed the Sun last September. Confirmed: it was an interstellar asteroid, an authentic piece of astronomical big game, traveling at a speed of 95,000 kilometers per hour.