An image released by the ESA on July 10, 2010 shows the Lutetia asteroid. Photo: AFP
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https://scmp.com/news/world/europe/article/2117392/mysterious-object-seen-speeding-past-sun-visitor-another-star Europe
Is mysterious object seen speeding past sun a ‘visitor’ from another star system?
Not the mysterious object, but Venus appearing as a small black dot against the massive surface of the Sun on its orbit between Earth and the centre of our solar system. Photo: EPA
A mysterious object detected hurtling past our sun could be the first space rock traced back to a different solar system, according to astronomers tracking the body.
While other objects have previously been mooted as having interstellar origins, experts say the latest find, an object estimated to be less than 400m in diameter, is the best contender yet.
“The exciting thing about this is that this may be essentially a visitor from another star system,” said Dr Edward Bloomer, astronomer at the Royal Observatory Greenwich.
If its origins are confirmed as lying beyond our solar system, it will be the first space rock known to come from elsewhere in the galaxy.
Published in the minor planet electronic circulars by the Minor Planet Centre at the Harvard-Smithsonian Centre for Astrophysics, the observations reveal that the object is in a strong hyperbolic orbit – in other words, it is going fast enough to escape the gravitational pull of the sun.
Objects originating from, and on long-period orbits within, our solar system can end up on a hyperbolic trajectory, and be ejected into interstellar space – for example if they swing close by a giant planet, since the planet’s gravity can cause objects to accelerate. But Dr Gareth Williams, associate director of the Minor Planet Centre, said that wasn’t the case for the newly discovered body.
“When we run the orbit for this [object] back in time, it stays hyperbolic all the way out – there are no close approaches to any of the giant planets that could have given this thing a kick,” he said. “If we follow the orbit out into the future, it stays hyperbolic, so it is coming from interstellar space and it is going to interstellar space.”
Computer generated image of our Solar System. Image: Shutterstock
Initially believed to be a comet, the object has been redesignated as an asteroid on account of analysis of its appearance, giving it the handle A/2017 U1.
According to observations made by astronomers, the object entered our solar system from above, passing just inside Mercury’s orbit and travelling below the sun, before turning and heading back up through the plane of the solar system towards the stars beyond. At its closest, on September 9, the object was 23.4 million miles from the sun.
First spotted earlier this month by a telescope at an observatory in Hawaii, astronomers around the world are now following the path of the object. Among them is Professor Alan Fitzsimmons from Queen’s University Belfast.
“It is fairly certain we are dealing with our first truly identified alien visitor,” he said. Fitzsimmons added that his team is currently working on measuring the objects’ position better to improve calculations of its trajectory, and to gather information relating to its chemical make-up, and size.
Early results, he said, suggest that the object might be similar in make-up to many of those of the Kuiper belt – a region past Neptune in our solar system that contains many small bodies.
Bloomer said we should not be too surprised if it does indeed turn out to have come from elsewhere in the galaxy.
An undated handout photo made available by the European Space Agency shows an artist's impression of a massive, comet-like object falling towards a white dwarf. New observations with the NASA/ESA Hubble Space Telescope show evidence for a belt of comet-like bodies orbiting the white dwarf, similar to the Kuiper Belt in our own Solar System. The findings also suggest the presence of one or more unseen surviving planets around the white dwarf which may have perturbed the belt sufficiently to hurl icy objects into the burned-out star. Photo: EPA
“Beyond the planets and past the Kuiper belt we think there is a region called the Oort cloud, which may be home to an astonishing number of icy bodies,” he said.
“Computer models have suggested that disturbances to the Oort cloud do send some stuff in towards the inner solar system, but it would also send stuff outwards as well – so we might be throwing out icy bodies to other star systems.”
If so, Bloomer said, there is no reason to suspect that disturbances to other star systems, as a result of gravitational interactions or other processes, wouldn’t throw material out too. “Just statistically, some of them are going to reach us,” he added.
Williams noted that objects could also be thrown out from the inner region of other solar systems as a result of gravitational interactions with giant planets, casting them into interstellar space.
And Fitzsimmons added that there was another possibility – that the object had been thrown out during the planet-forming period of another solar system.
The hottest known planet in the Milky Way galaxy may also be its shortest-lived world. The doomed planet is being eaten by its parent star, according to observations made by a new instrument on NASA's Hubble Space Telescope, the Cosmic Origins Spectrograph (COS). The planet may only have another 10 million years left before it is completely devoured.The planet, called WASP-12b, is so close to its sunlike star that it is superheated to nearly 2,800 degrees Fahrenheit and stretched into a football shape by enormous tidal forces. The atmosphere has ballooned to nearly three times Jupiter's radius and is spilling material onto the star. The planet is 40 per cent more massive than Jupiter. Photo: AFP
“We know now that many stars, probably the majority of stars in our galaxy, have planets going around them, and we know from studying those stars but also primarily from studying our own solar system, that planet building is a very messy process,” he said.
With large quantities of material thrown out into interstellar space, said Fitzsimmons, is was expected that there would be objects travelling between the stars.
“This object itself could have been between the stars for millions or billions of years before we spotted it as it plunged into our solar system,” he said.
“There are mysteries to be solved here.”