Interstellar journeys through vast expanse of space from star to star are literally all-day in science fiction movies and novels. In real world, Voyager 1 spacecraft, which started 40 years ago and is currently furst into space, has just left our solar system. Even Neanderthals would have had to send Voyager 1 on journey about 75,000 years ago, so that probe would reach Proxima Centauri with its velocity of around 60,000 km/h in our present times, neighboring star of Sun.
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Accordingly, long journey times of hundreds of thousands or even millions of years would have a body from anor solar system on hump that would come with us. It doesn’t necessarily have to be a spaceship with alien creatures. Asteroids or comets are also possible. Until recently, however, it was unknown wher such celestial bodies exist in foreign solar systems at all.
Now, astronomer Robert Weryk of University of Hawaii has actually discovered first extra-solar asteroid that penetrated interstellar space coming into our solar system (Meech Weryk et al., Nature, 2017). On September 9th, maximum of 400 metres, extremely elongated and reddish chunks called “A/2017 U1” (now renamed “Oumuamua”, Hawaiian for “ambassadors”) on a trajectory bent by attraction of sun in a narrow curve past it, before he A month later, at a distance of about 24 million kilometers, flew past Earth.
A cloud of billions of comets
Shortly reafter, on October 19, he was tracked by “Pan-STARRS” telescope, which is located on volcano Haleakala on Hawaii Island Maui and systematically scans skies for asteroids and comets – especially those that come close to earth. So far, all se NEOs (near-Earth objects) originally came from two different regions of solar system. The icy comets probably originate from edge of solar system. There, according to Dutch astronomer Jan Hendrik Oort 1950, a cloud of billions of comets surrounds solar system. Every few million years, anor star of Milky Way may come a little closer to our solar system. The gravitational attraction of this star changes comet orbits in Oort cloud. Some comets are hurled into interior of solar system, some out into space.
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The rocky asteroids, on or hand, fly mainly on orbits around sun, which run between our outer neighbor planet Mars and giant planet Jupiter, in asteroid belt. For asteroids, gigantic Jupiter gravitational fate, which depending on geometric situation, can throw asteroids out of orbit. Some into region of inner planets, some out to stars.
Otto Wöhrbach
The author studied physics, mamatics and philosophy in Tübingen and led planetarium in Freiburg until 2016. Since n he has been writing as a freelance author about astronomy and planetary research, especially for “Tagesspiegel” and “Baden Zeitung”.
Both asteroids between Mars and Jupiter and Comets from edge of solar system are presumably remnants from those distant times 4.6 billion years ago, when in a gas and dust mist matter was condensed to sun and its eight planets. Such birth processes are apparently norm in cosmos. In meantime, astronomers have already found planets at around 3,000 stars of Milky Way. Why, y asked mselves, should not re, as at birth of our solar system, asteroids and comets have arisen? And why shouldn’t similar gravitational spinal effects have driven some of se asteroids and comets out of ir respective solar systems into interstellar space on orbits that would lead m leppien into or solar systems?
150,000 kilometers per hour fast
Therefore, earthly astronomers were now less surprised by first discovery of such an extra solar celestial body in solar system, but rar by fact that y could only now discover such a hiker from distant worlds. It could also have been an extra solar comet. But n his icy surface would be thawed near sun and gas would have been blown apart by solar wind to a more or less long typical comet tail. However, since even one of large telescopes of European sourn ESO in Chile with its 8.2 meter mirror showed no signs of a tail, it must probably be an asteroid.
The intruder was betrayed by his great speed: when he scratched his curve around sun, he had a speed of more than 150,000 km/h. This is far too fast for a closed elliptical orbit around sun in spell of its attraction. In meantime, gravitational force of sun has slowed down asteroid that has been removed from it to a speed of under 100,000 km/h. But she will not be able to prevent him from going out on an open hyperbolic trajectory into space between stars from which he had come – on his journey from a distant or solar system somewhere in Milky Way to us.
