Cigar-spaced shape object Oumuamua may not be comet – and could be alien tech, shock study warns
A MYSTERIOUS interstellar visitor that flew past Earth three years ago may have been an alien spacecraft after all, scientists claim.
That's because the prevailing explanation of the cigar-shaped object Oumuamua's origins are fatally flawed, according to a shock new study.
Oumuamua took the world by storm in October 2017 when it was identified as the first known visitor from another star system.
A pair of Harvard scientists suggested the long and thin object was a spacecraft, sparking a frantic flurry of scans by astronomers as it flew by.
Experts found no signs of alien signals, and eventually concluded that the space guest was a comet – a finding supposedly ruled out by the new study.
Scientists had put forward earlier this year that Oumuamua's molecular makeup suggested the comet was made of frozen hydrogen.
That would explain how Oumuamua was able to propel itself, as hydrogen gas blasted from the object would have pushed it through space.
However, in a paper published Monday, two astrophysicist argue this scenario couldn't happen in the real world.
The team say such "hydrogen icebergs" cannot last the long journey between stars thought to have been taken by Oumuamua.
"We were suspicious that hydrogen icebergs could not survive the journey – which is likely to take hundreds of millions of years," said Professor Avi Loeb of Harvard University, one of the study's coauthors.
What is Oumuamua?
Here's what you need to know...
- Oumuamua is a cigar-shaped asteroid that sped past Earth in 2017
- Some boffins think the space rock was an alien probe sent by a distant civilisation
- It was spotted by scientists in Hawaii, and its name means 'scout' in Hawaiian
- Researchers involved in SETI- the Search for Extra Terrestrial Intelligence - used a powerful dish to scan Oumuamua
- They found no signs of radio signals, suggesting it wasn't an alien spaceship after all
- Recent research suggests that the object could have been ejected by a gas giant planet
- It's now moving away from Earth so fast that we're unlikely to ever find out
He added that this is because ";they evaporate too quickly."
Professor Loeb was one of the original Harvard advocates of the theory that Oumuamua was made from alien technology.
Writing in , he and Korea Astronomy and Space Science Institute (KASI) scientist Dr Thiem Hoang pick several holes in the popular comet theory.
Oumuamua baffled scientists because it seemed to behave like something between a comet and an asteroid.
The interstellar visitor was long and thin – an unusual shape – and travelled at 200,000mph while rotating in a "tumbling" motion.
Perhaps strangest of all was that the object appeared to accelerate on its journey, suggesting it was powered by something.
Some scientists think that rising speed was the work of an alien engine, while others believe it was simply caused by the natural ejection of gas.
Another argument against the comet theory is that a hydrogen iceberg of this kind could not form, researchers wrote in the new paper.
What's the difference between an asteroid, meteor and comet?
- Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
- Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
- Meteor: If a meteoroid enters the Earth's atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it'll look like a streak of light in the sky, because the rock is burning up
- Meteorite: If a meteoroid doesn't vapourise completely and survives the trip through Earth's atmosphere, it can land on the Earth. At that point, it becomes a meteorite
- Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)
“An accepted route to form a km-sized object is first to form grains of micron-size, then such grains grow by sticky collisions,” said Dr Hoang.
"However, in regions with high gas density, collisional heating by gas collisions can rapidly sublimate the hydrogen mantle on the grains, preventing them from growing further."
The new theory means researchers cannot firmly rule out that Oumuamua is an alien spacecraft.
Most scientists still agree, however, that the object was either an asteroid or a comet.
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In other news, an asteroid the size of a car zipped past Earth on Sunday in what scientists say is the closest flyby on record.
Nasa recently snapped a stunning image of a 2,000-foot dust whirlwind raging across Mars.
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And, Mars may have taken as long as 20million years to form, scientists now claim.
What do you think Oumuamua was? Let us know in the comments!
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