Alien comet speeding towards Earth could be visitor from another solar system, say scientists

Mysterious object would be the second ever interstellar traveller known to have visited us

Andrew Griffin
Thursday 12 September 2019 09:19
Alien comet speeding towards earth could be visitor from another solar system, say scientists

Astronomers might have spotted an interstellar visitor to our solar system, for only the second ever time.

A mysterious rock, which has been speeding through space towards Earth, might have made its way from an entirely different star.

The object appears to be taking a bizarre orbit that suggests it has arrived here from elsewhere, scientists said. Rather than the elliptical orbit that objects in our own solar system have as they fly around the Sun, the new object's movement has a hyperbolic shape, suggesting it is on a journey through the solar system rather than around it.

The rock would follow 'Oumuamua, the first interstellar object ever observed in our solar system, which was first spotted in 2017 and has been mystifying scientists ever since. Scientists still know very little about the unusual object, and its strange behaviour was so unusual that it even led some to suggest it could actually be an alien spacecraft.

If the new object is in fact another interstellar visitor, it could shed light on that mysterious object. And it would mark a major breakthrough in our understanding of how such objects are flung through the universe.

The new object was first spotted at the end of August, by an amateur astronomer called Gennady Borisov who saw it through a telescope he made himself. He posted the possible discovery online and other researchers rushed to confirm it.

It has now been spotted through other observations, which have allowed astronomers to learn more about it. That extra work did indeed suggest that it was another visitor to our solar system, prompting Harvard's Minor Planet Center to release an official report on the object.

"Based on the available observations, the orbit solution for this object has converged to the hyperbolic elements shown below, which would indicate an interstellar origin," it wrote. "A number of other orbit computers have reached similar conclusions, initially D. Farnocchia (JPL), W. Gray, and D. Tholen (UoH).

"Further observations are clearly very desirable, as all currently-available observations have been obtained at small solar elongations and low elevations. Absent an unexpected fading or disintegration, this object should be observable for at least a year."

One of the things that made 'Oumuamua so inscrutable to scientists was that it was spotted on its way out of the solar system, giving them only a very limited time to make any observations of it. The new object looks as if it will be around for longer, giving astronomers much more of an opportunity to try and understand what it is and where it came from.

For now, the object is called C/2019 Q4 (Borisov), the Minor Planet Center said. Further observations will be required to confirm that it is indeed an interstellar traveller, at which point it will be given an updated name.

Michele Bannister, a scientist from Queen's University Belfast who worked on the discovery and examination of Oumuamua, tweeted to warn that objects with similar orbits had been spotted before – and then found to be more normal than we had realised.

"This is not the first object since 2017/1I, better known as ʻOumuamua, to show a hyperbolic orbit," she wrote on Twitter. "Several short-arcs have flourished and slid slowly into the demise of straightforward parabolas.

"What it took? More observations."

Astronomers have long said that more visitors should be spotted fairly regularly in the future, and that they will finally help us understand where these objects are coming from and how unusual they are. In 2022, the Large Synoptic Survey Telescope will be switched on and allow them to see many more, they hope.

“In the next 10 years, we expect to begin seeing more objects like ‘Oumuamua. The LSST will be leaps and bounds beyond any other survey we have in terms of capability to find small interstellar visitors,” said Matthew Knight, an associate research scientist in the University of Maryland’s department of astronomy, earlier this year.

“We may start seeing a new object every year. That’s when we’ll start to know whether ‘Oumuamua is weird, or common. If we find 10-20 of these things and ‘Oumuamua still looks unusual, we’ll have to re-examine our explanations.”

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