A mysterious asteroid called Oumuamua, the first interstellar object ever seen in the solar system, could be a gigantic alien solar sail send to look for signs of life, a new study has claimed.

Astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) analyzed the strange cigar shape of the object, and an unexpected boost in speed and shift in trajectory as it passed through the inner solar system last year.

They concluded that the strange asteroid 'might be a lightsail of artificial origin.'

The study – 'Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration?', which recently appeared online – was conducted by Shmuel Bialy, a postdoctoral researcher at the CfA's Institute for Theory and Computation (ITC) and Professor Abraham Loeb, the director of the ITC, the Frank B. Baird Jr. Professor of Science at Harvard University, and the head chair of the Breakthrough Starshot Advisory Committee.

The researchers say the strange acceleration could the the result of solar radiation pushing a giant solar sail.

They found a sail that was only a fraction of a millimeter thick (0.3-0.9 mm) would be sufficient for a sheet of solid material to survive the journey through the entire galaxy.

Lightsails with similar dimensions have been designed and constructed by humans, including the Japanese-designed IKAROS project and the Starshot Initiative with which he is involved.

'Considering an artificial origin, one possibility is that ‘Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment,' they wrote.

'Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization,' they added.

Another option, which explains the lack of communication, a lack of any kind of signal could mean the giant object is actually an 'alien shipwreck'.

Professor Loeb previously wrote in Scientific American, 'Oumuamua could be the first known case of an artificial relic which floated into our Solar System from interstellar space.

'This opportunity establishes a potential foundation for a new frontier of space archaeology, namely the study of relics from past civilizations in space,'

'Finding evidence for space junk of artificial origin would provide an affirmative answer to the age-old question 'Are we alone?'. This would have a dramatic impact on our culture and add a new cosmic perspective to the significance of human activity.'

Loeb told Universe Today, 'Oumuamua could be an active piece of alien technology that came to explore our Solar System, the same way we hope to explore Alpha Centauri using Starshot and similar technologies'

'The alternative is to imagine that `Oumuamua was on a reconnaissance mission. The reason I contemplate the reconnaissance possibility is that the assumption that `Oumumua followed a random orbit requires the production of ~10^{15} such objects per star in our galaxy. This abundance is up to a hundred million times more than expected from the Solar System, based on a calculation that we did back in 2009. A surprisingly high overabundance, unless `Oumuamua is a targeted probe on a reconnaissance mission and not a member of a random population of objects.'

The cigar-shaped object, named 'Oumuamua, was spotted by the Haleakala observatory in Hawaii on October 19 last year.

A NASA reconstruction of the 'outgassing' of of ′Oumuamua. The cigar-shaped object was first spotted by the Haleakala observatory in Hawaii on October 19 last year. Now a new study claims it could be a solar sail from an alien civilization.

Its appearance and behaviour baffled scientists and led to speculation that it might even be an alien artefact - and now they have found it got a strange speed boost while passing through, which has helped identify it as a comet.

Telescopes first spotted the mysterious red-tinged object last October as it zipped through the inner solar system.

Since then, astronomers have flip-flopped between comet and asteroid for our first confirmed interstellar guest.

'Our high-precision measurements of ′Oumuamua's position revealed that there was something affecting its motion other than the gravitational forces of the Sun and planets,' said Marco Micheli of ESA's (European Space Agency) Space Situational Awareness Near-Earth Object Coordination Centre in Frascati, Italy, and lead author of a paper describing the team's findings.

The speed boost was consistent with the behavior of a comet, said co-author Davide Farnocchia of the Center for Near Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory (JPL).

'This additional subtle force on ′Oumuamua likely is caused by jets of gaseous material expelled from its surface,' said Farnocchia.

'This same kind of outgassing affects the motion of many comets in our solar system.'

Comets normally eject large amounts of dust and gas when warmed by the Sun.

Karen Meech, an astronomer at the University of Hawaii's Institute of Astronomy and co-author of the study, speculated that small dust grains, present on the surface of most comets, eroded away during ′Oumuamua's long journey through interstellar space.

'The more we study ′Oumuamua, the more exciting it gets,' Meech said.

'I'm amazed at how much we have learned from a short, intense observing campaign. I can hardly wait for the next interstellar object!'

′Oumuamua, less than half a mile in length, now is farther away from our Sun than Jupiter and traveling away from the Sun at about 70,000 mph as it heads toward the outskirts of the solar system.

In only another four years, it will pass Neptune's orbit on its way back into interstellar space.

Because ′Oumuamua is the first interstellar object ever observed in our solar system, researchers caution that it's difficult to draw general conclusions about this newly-discovered class of celestial bodies.

However, observations point to the possibility that other star systems regularly eject small comet-like objects and there should be more of them drifting among the stars.

Future ground- and space-based surveys could detect more of these interstellar vagabonds, providing a larger sample for scientists to analyze. </s> The latest theory on ‘Oumuamua comes from a study published on Thursday by Shmuel Bialy and Abraham Loeb, a pair of astronomers with the Harvard Smithsonian Center for Astrophysics.

When scientists reviewed data collected by the Pan-STARRS-1 survey of ‘Oumuamua's closest flyby of the sun on September 9, 2017, they noted that the mysterious rock gained speed, rather than slowing down. Researchers at the time explained that the increase in ‘Oumuamua's velocity was likely explained by outgassing, the release of gas trapped or frozen inside the rock. The object itself was later classified as a comet by officials.

However, this explanation didn't sit right with Bialy and Loeb, who argue that had outgassing been the cause of ‘Oumuamua's increased velocity, it would've sent the interstellar object into a spin, which wasn't observed.

The pair suggested that ‘Oumuamua could actually be a light sail, a spacecraft that relies on radiation pressure for power, that's been sent from an alien civilization looking for signs of life in our solar system.

"We explain the excess acceleration of ‘Oumuamua away from the sun as the result of the force that the sunlight exerts on its surface. For this force to explain measured excess acceleration, the object needs to be extremely thin, of order a fraction of a millimeter in thickness but tens of meters in size," Loeb told Universe Today via email.

"This makes the object lightweight for its surface area and allows it to act as a light sail. Its origin could be either natural (in the interstellar medium or proto-planetary disks) or artificial (as a probe sent for a reconnaissance mission into the inner region of the solar system)."

Bialy and Loeb later explained in their work that should their theory prove true, there is the slight possibility that the light sail could even just be a "defunct sail floating under the influence of gravity and stellar radiation."

But then again, alien civilizations.

"The alternative is to imagine that ‘Oumuamua was on a reconnaissance mission. The reason I contemplate the reconnaissance possibility is that the assumption that ‘Oumumua followed a random orbit requires the production of ~10^{15} such objects per star in our galaxy. This abundance is up to a hundred million times more than expected from the solar system, based on a calculation that we did back in 2009," Loeb wrote.

"A surprisingly high overabundance, unless ‘Oumuamua is a targeted probe on a reconnaissance mission and not a member of a random population of objects."

Questions remain regarding the origin of ‘Oumuamua, and considering the rock is no longer in our solar system and is much too far away for researchers to observe, the lab coats might be in the dark for some time on the matter. </s> On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar asteroid, named 1I/2017 U1 (AKA 'Oumuamua).

In the months that followed, multiple follow-up observations were conducted that allowed astronomers to get a better idea of its size and shape, while also revealing that it had the characteristics of both a comet and an asteroid.

Interestingly enough, there has also been some speculation that based on its shape, 'Oumuamua might actually be an interstellar spacecraft (Breakthrough Listen even monitored it for signs of radio signals!).

A new study by a pair of astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) has taken it a step further, suggesting that 'Oumuamua may actually be a light sail of extra-terrestrial origin.

The study – "Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration?", which recently appeared online – was conducted by Shmuel Bialy and Prof. Abraham Loeb. Whereas Bialy is a postdoctoral researcher at the CfA's Institute for Theory and Computation (ITC), Prof. Loeb is the director of the ITC, the Frank B. Baird Jr. Professor of Science at Harvard University, and the head chair of the Breakthrough Starshot Advisory Committee.

To recap, 'Oumuamua was first spotted by the Pan-STARRS-1 survey 40 days after it made its closest pass to the Sun (on September 9th, 2017).

At this point, it was about 0.25 AU from the Sun (one-quarter the distance between Earth and the Sun), and already on its way out of the Solar System. In that time, astronomers noted that it appeared to have a high density (indicative of a rocky and metallic composition) and that it was spinning rapidly.

While it did not show any signs of outgassing as it passed close to our Sun (which would have indicated that it was a comet), a research team was able to obtain spectra that indicated that 'Oumuamua was more icy than previously thought.

Then, as it began to leave the Solar System, the Hubble Space Telescope snapped some final images of 'Oumuamua that revealed some unexpected behavior.

After examining the images, another international research team discovered that 'Oumuamua had increased in velocity, rather than slowing down as expected. The most likely explanation, they claimed, was that 'Oumuamua was venting material from its surface due to solar heating (AKA outgassing).

The release of this material, which is consistent with how a comet behaves, would give 'Oumuamua the steady push it needed to achieve this boost in velocity.

To this, Bialy and Loeb offer a counter-explanation. If 'Oumuamua were in fact a comet, why then did it not experience outgassing when it was closest to our Sun?

In addition, they cite other research that showed that if outgassing were responsible for the acceleration, it would have also caused a rapid evolution in 'Oumuamua's spin (which was not observed).

Basically, Bialy and Loeb consider the possibility that 'Oumuamua could in fact be a light sail, a form of spacecraft that relies on radiation pressure to generate propulsion – similar to what Breakthrough Starshot is working on. Similar to what is planned for Starshot, this light sail may been sent from another civilization to study our Solar System and look for signs of life. As Prof. Loeb explained to Universe Today via email:

"We explain the excess acceleration of `Oumuamua away from the Sun as the result of the force that the Sunlight exerts on its surface. For this force to explain measured excess acceleration, the object needs to be extremely thin, of order a fraction of a millimeter in thickness but tens of meters in size. This makes the object lightweight for its surface area and allows it to act as a light-sail. Its origin could be either natural (in the interstellar medium or proto-planetary disks) or artificial (as a probe sent for a reconnaissance mission into the inner region of the Solar System)."

Based on this, Bialy and Loeb went about calculating the likely shape, thickness, and mass-to-area ratio that such an artificial object would have. They also attempted to determine whether this object would be able to survive in interstellar space, and whether or not it would be able to withstand the tensile stresses caused by rotation and tidal forces.

What they found was that a sail that was only a fraction of a millimeter thick (0.3-0.9 mm) would be sufficient for a sheet of solid material to survive the journey through the entire galaxy – though this depends greatly on 'Oumuamuam's mass density (which is not well-contrained).

Thick or thin, this sail would be able to withstand collisions with dust-grains and gas that permeate the interstellar medium, as well as centrifugal and tidal forces.

As for what an extra-terrestrial light sail would be doing in our Solar System, Bialy and Loeb offer some possible explanations for that. First, they suggest that the probe may actually be a defunct sail floating under the influence of gravity and stellar radiation, similar to debris from ship wrecks floating in the ocean. This would help explain why Breakthrough Listen found no evidence of radio transmissions.

Loeb further illustrated this idea in a recent article he penned forScientific American, where he suggested that 'Oumuamua could be the first known case of an artificial relic which floated into our Solar System from interstellar space.

What's more, he notes that lightsails with similar dimensions have been designed and constructed by humans, including the Japanese-designed IKAROS project and the Starshot Initiative with which he is involved.

"This opportunity establishes a potential foundation for a new frontier of space archaeology, namely the study of relics from past civilizations in space," Loeb wrote.

"Finding evidence for space junk of artificial origin would provide an affirmative answer to the age-old question 'Are we alone?'. This would have a dramatic impact on our culture and add a new cosmic perspective to the significance of human activity."

On the other hand, as Loeb told Universe Today, 'Oumuamua could be an active piece of alien technology that came to explore our Solar System, the same way we hope to explore Alpha Centauri using Starshot and similar technologies:

"The alternative is to imagine that `Oumuamua was on a reconnaissance mission. The reason I contemplate the reconnaissance possibility is that the assumption that `Oumumua followed a random orbit requires the production of ~10^{15} such objects per star in our galaxy. This abundance is up to a hundred million times more than expected from the Solar System, based on a calculation that we did back in 2009. A surprisingly high overabundance, unless `Oumuamua is a targeted probe on a reconnaissance mission and not a member of a random population of objects."

According to Loeb, that there's also the fact that 'Oumuamua's orbit brought it to within 0.25 AU of the Sun, which is a good orbit for intercepting Earth without experiencing too much solar irradiation. In addition, it came to within 0.15 AU of Earth, which could have been the result of orbital corrections designed to facilitate a flyby.

Alternately, he states that it is possible that hundreds of such probes could be sent so that one of them got close enough to Earth to study it. The fact that the Pan STARRS-1 survey barely detected 'Oumuamua at its closest approach could be seen as an indication that there are many other such objects that were not detected, bolstering the case for 'Oumuamua being one of many such probes.

Considering that astronomers recently concluded that our Solar System has likely captured thousands of interstellar objects like 'Oumuamua, this opens the possibility for future detections which could help prove (or disprove) the case for an interstellar light sail.

Naturally, Bialy and Loeb acknowledge that are still too many unknowns to say with any certainty what 'Oumuamua really is. And even if it does happen to be a piece of natural rock, all other asteroids and comets that have previously been detected have had mass-to-area ratios orders of magnitude larger than the current estimates for 'Oumuamua.

That, and the fact that radiation pressure appears to be capable of accelerating it, would mean that 'Oumuamua represents a new class of thin interstellar material that has never before been seen. If true, that opens up a whole new set of mysteries, such as how such material was produced and by what (or whom).

While it has been beyond the reach of our telescopes for almost a year now, 'Oumuamua is sure to remain the subject of intense study for many years to come. And you can bet astronomers will be on the lookout for more of them! After all, "the Ramans do everything in threes", right?

This article was originally published by Universe Today. Read the original article. </s> Remember that cigar-shaped interstellar object that whizzed through our Solar System last year? It was pretty weird, right? Well, new research shows ‘Oumuamua is even stranger than we realized.



‘Oumuamua, pronounced “oh-MOO-ah-MOO-ah,” is a comet and not an asteroid, according to research published yesterday in Nature. That’s not a huge revelation, as many scientists had already assumed as much. What’s special about this new paper, however, is that it offers tangible evidence to bolster the case.

Seems like a fine point, but there’s a big difference between asteroids and comets. Both types of objects are leftovers from the formation of the Solar System, but where asteroids are composed of metals and rocky material, comets are made from ice, dust, and rocks. Typically, comets have elongated orbits that take them to the outer reaches of the Solar System, but as they venture inwards, the Sun’s rays cause gas and dust to shear off, producing a glowing cloud of material called a coma and a visible tail.

In the case of ‘Oumuamua, the dark, 2,620-foot-long object was detected on October 19, 2017 using Hawaii’s Haleakala Observatory, and scientists have been tracking it ever since. ‘Oumuamua came to within 20.5 million miles (33 million km) of Earth before heading back toward interstellar space—and it appears to be in a hurry. By combining data collected from the NASA/ESA Hubble Space Telescope, the Canada-France-Hawaii Telescope, ESO’s Very Large Telescope, and the Gemini South Telescope, a team led by Marco Micheli from the European Space Agency noticed something odd about ‘Oumuamua: It’s moving faster than expected.

The extra speed isn’t ludicrous by any means, but it’s still measurable. ‘Oumuamua is still slowing down thanks to the gravitational influence of our Sun, but not at the rate expected by celestial mechanics. The reason, say the authors of the new study, is that ‘Oumuamua is still venting material from its surface. Solar heating is producing an effect called outgassing, and the material ejected from the object’s surface is creating a tiny amount of thrust. It’s like a built-in propulsion system, but one that only becomes active inside the warm, cozy realms of a star system.



To make sure the acceleration effect was not being caused by something else, the researchers considered scenarios like solar wind, a collision with another object, its mass being different than calculated, and other known or suspected astrophysical phenomena. However, “these explanations are all either physically unrealistic or insufficient to explain the observed behavior,” write the authors in the study.

“Also, the unlikely theory that ‘Oumuamua is an interstellar spaceship was rejected: the smooth and continuous change in speed is not typical for thrusters and the object is tumbling on all three axes, speaking against it being an artificial object,” according to Hubble press release. As a related aside, research from late last year came to the same conclusion.



The suspected presence of outgassing was the smoking gun needed to prove that ‘Oumuamua is a comet and not an asteroid.

“We think this is a tiny, weird comet,” said Micheli in a press release. “We can see in the data that its boost is getting smaller the farther away it travels from the Sun, which is typical for comets.”

Now, you’re probably thinking, “What the hell, Dvorsky, a minute ago you said comets produce a visible coma and tail when they get close to the Sun! But ‘Oumuamua doesn’t exhibit any of this!” Fair point, but there is a good reason for this, one demonstrating how freakin’ weird this object really is.

‘Oumuamua, the researchers speculate, is venting unusually large, coarse dust grains. Micheli’s team is theorizing that small dust grains, which that typically litter the surface of comets, eroded during the course of ‘Oumuamua’s epic journey through interstellar space (we have no idea how old this object is, so who knows how long it’s been careening through the Milky Way, which formed 13.5 billion years ago). All that’s left on this comet are the larger dust grains. If ‘Oumuamua is producing a cloud composed of these large particles, it would be too dim for Hubble to see it. But the unexpected deviation in its acceleration suggests these grains are very much there, and that ‘Oumuamua is, or was, in an outgassing phase during its brief time in our Solar System.

Sadly, this new result means it’s going to be exceptionally tough for astronomers to figure out where in the galaxy this object came from. If it had been an asteroid with a boring and predictable speed, scientists should have been able to backtrack its trajectory to its star system of origin. But with its variable speed, that’ll now be a physics task of herculean proportions, and probably something best suited for a future supercomputer.

It came, we saw, it’s quickly leaving. But we’re still learning some amazing things about this messenger from afar. </s> WASHINGTON (Reuters) - The reddish cigar-shaped object called ‘Oumuamua spotted last year tumbling through space is a comet, scientists said on Wednesday, solving the mystery over how to classify the first interstellar object found passing through our solar system.

This artist’s impression shows the first interstellar asteroid, `Oumuamua as it passes through the solar system after its discovery in October 2017. European Southern Obervatory/M. Kornmesser/Handout via REUTERS/Files

Astronomers said they closely examined the trajectory of ‘Oumuamua, which measures about a half-mile (800 meters) long, as it speeds through our cosmic neighborhood after being evicted somehow from a distant star system.

They found that it is deviating slightly from a path that would be explained purely by the Sun’s gravitational pull because of what apparently is a very small emission of gas from its surface, indicative of a comet.

‘Oumuamua (pronounced oh-MOO-uh-MOO-uh) initially was pegged as a comet, but it lacks the tail of gas and dust characteristic of many comets, and some scientists argued that it was perhaps a dry asteroid.

“It does not display any tail in any observation we obtained,” said astronomer Marco Micheli of the European Space Agency’s SSA-NEO Coordination Centre in Italy, who led the study, published in the journal Nature.

“However, our analysis shows that the amount of emitted gas that is needed to generate this extra force we see would have been so small as to be invisible in our observations,” he said in an email.

This “extra force” acting on the object’s trajectory amounts to only about 0.1 percent of the Sun’s gravitational attraction.

‘Oumuamua was first detected last October by the University of Hawaii’s Pan-STARRS1 telescope. Its name refers in the native Hawaiian language to a messenger arriving from a great distance.

It previously slingshot past the Sun traveling at roughly 196,000 miles per hour (315,000 km per hour) and is heading out of the solar system in the direction of the constellation Pegasus. ‘Oumuamua as of last month was roughly the same distance from the Sun as Jupiter.

Astronomers suspect that more visitors from other star systems will be discovered passing through our solar system.

“The discovery of ‘Oumuamua is an absolute first in the field, and it provided our first opportunity to study an object coming from another star and planetary system,” Micheli said. “The existence of these objects was expected, but seeing one for the first time, and being able to study it in detail, is a unique chance to know more on these distant systems, and how they formed.” </s> It turns out that 'Oumuamua, our first known interstellar visitor, is a comet after all.

This cosmic object was first discovered in 2017 by researchers with the Panoramic Survey Telescope Rapid Response System (Pan-STARRS). Its strange, cigar-like shape, its lack of both a tail and a coma, has made it difficult to categorize — some even suggested it could hold extraterrestrial life. It has so far been classified as a comet, classified as an asteroid, and even put into a new "interstellar objects" class.

'Oumuamua, since its discovery, has been very difficult for researchers to study and understand because, since "this was actually a faint object … we had very little time to observe it," Karen Meech, an astronomer at the University of Hawaii and co-author on the new work, told Space.com. But now, in a paper published today (June 27) in the journal Nature, researchers seem to have concluded that the mysterious interstellar body is a comet. Scientists still don't know where the dark-red, 2,624-foot-long (800 meter) object came from, but at least part of the mystery has now been put to rest. ['Oumuamua: The Solar System's 1st Interstellar Visitor Explained in Photos]

Tumbling through our solar system, 'Oumuamua's movement and behavior along this journey has led researchers to their conclusion. They found that the arc that 'Oumuamua traveled along can't be entirely explained by the gravitational pull of the sun, planets and other solar system objects. So, as the researchers explained in the new paper, part of the object's acceleration isn't caused by gravity.

Classifying the object as a comet explains its arcing movement and nongravitational acceleration, as comets can be propelled by gas they release.

There are other possible explanations for this acceleration, like magnetic interaction with the solar wind, pressure from solar radiation, and forces of drag and friction. But the researchers ruled these out.

This leaves the remaining explanation that 'Oumuamua is propelled partially by gas, which would indicate that it is a comet.

Meech said that this study "conclusively ends" the mystery of what this object really is, while adding that "there's never a hundred percent guarantee on anything."

These researchers are "inferring that it is a comet based on all available evidence, but there is no other explanation," Meech said. She added that, if they wanted concrete proof that it is a comet, they would have needed to see "a tail of dust and gas, but that just wasn't possible in this case."

Still, 'Oumuamua is anything but a standard comet. It lacks a coma, which is the cloud of gas and dust that usually envelops a comet's core, and researchers didn't observe a classic comet tail. The object also has a noticeably unique appearance. So, with the knowledge that they have, the researchers found that 'Oumuamua must be a comet.

The main remaining mystery about 'Oumuamua is its origin. Researchers still don't know where the object came from and, according to Meech, knowing that the object has nongravitational motion will make it even more difficult to figure out its source. </s> The traveler, which was given the name `Oumuamua, Hawaiian for "messenger from afar," was first discovered in 2017 by researchers with the Panoramic Survey Telescope Rapid Response Systems (Pan-STARRS), located on Maui. From the moment researchers spotted the oddly shaped object, they weren't exactly sure how to classify it: first it was a comet, then an asteroid, before astronomers deemed it simply an interstellar object.

But now, thanks to the hard work of researchers led by the European Space Agency, `Oumuamua is back to being considered a comet, since it's not solely being guided by the sun's gravity as a planet or asteroid would be, according author Marco Micheli, the lead author on the study.

​"Unexpectedly, we found that `Oumuamua was not slowing down as much as it should have due to just gravitational forces," Micheli told USA Today. "We think this is a tiny, weird comet… we can see in the data that its boost is getting smaller the farther away it travels from the sun, which is typical for comets."

"It's definitely an exciting discovery," he added.

According to Micheli, after analyzing `Oumuamua's trajectory, researchers determined that the 800-meter-long object wasn't solely being pushed on its journey by a gravitational pull of the sun, planets and any other solar system objects.

By slapping the comet label on the mysterious object, researchers are better able to explain `Oumuamua's non-gravitational acceleration, since comets are propelled by outgassing, Space.com reported.

Though `Oumuamua isn't your typical comet, as it lacks a coma — the cloud of gas and dust that envelops around the nucleus of the comet — the mystery remaining behind the object now is its origin. </s> An interstellar asteroid that drifted past our sun recently has been confirmed to have originated from another solar system.

Our solar system has many visiting chunks of space debris passing through, but we have never found one that has come from another solar system – until now.

A team of astronomers has identified one such cosmic traveller, dubbed 1I/2017 or ‘Oumuamua (the Hawaiian word for scout).

According to The Guardian, the object was first spotted travelling past the sun last month.

At first glance, it looked very similar to the comets and asteroids seen in our own solar system. However, unlike this space debris, ‘Oumuamua’s orbit was calculated as being impossible to achieve by one that originated in our own system and could be one of as many as 10,000 that are nearby.

The object is believed to be an incredibly dark red colour, with 96pc of all light that hits it being absorbed.

The appearance of red means that it contains organic, carbon-based molecules. This could add even greater credence to the theory of transpermia, whereby comets and asteroids containing organic molecules could have collided with Earth and ‘seeded’ life here.

Findings on ‘Oumuamua have been published by two sets of researchers from the University of Hawaii and UCLA, respectively.

The team from Hawaii calculated that ‘Oumuamua is just 400 metres long with a rotation once every 7.3 hours.

The UCLA team estimated that the other 10,000 or so objects similar to the asteroid could be located closer to our sun than Neptune, with three objects arriving and three leaving our solar system on a daily basis.

By better understanding how ‘Oumuamua and other objects like it enter our solar system, we can learn more about how planets formed in their native star system. </s> Astronomers around the world were positively tickled last year when we detected our first interstellar object inside the solar system. The object was named ‘Oumuamua, a term of Hawaiian origin meaning “a messenger from afar arriving first.” Telescopes around the world turned to watch as our visitor rocketed off into oblivion, and scientists eventually decided it was an asteroid. However, some new data calls that assessment into question. ‘Oumuamua may have been a comet after all.

The scientific community has long expected an interstellar visitor to show up, and ‘Oumuamua was undeniably from another star. It shot past us with such haste there was no way it could have started in our solar system — even a gravity boost from Jupiter wouldn’t have given a local object matching speed and trajectory.

So, ‘Oumuamua’s appearance wasn’t a shock, but the 800-meter cigar-shaped object still wasn’t exactly what we expected. Scientists believed the first interstellar object in our solar system would be a comet. If other solar systems are anything like ours, there should be a cloud of comets at the very edge. It wouldn’t take much for these objects to break away and sail through interstellar space. However, ‘Oumuamua looked more like an asteroid than a comet.

The hallmark of a comet is the way the icy body heats up as it passes close to the sun, leading to the formation of a “coma.” That’s why comets have tails and asteroids don’t. ‘Oumuamua didn’t have a visible tail. Researchers from the University of Hawaii Institute for Astronomy (where ‘Oumuamua was discovered) have kept watch on the object using the Hubble Space Telescope, and the latest data suggests something other than gravity has affected its path.

Astronomers have attempted to determine if the solar wind or radiation could have tweaked ‘Oumuamua’s trajectory using computer models, but nothing fit with the observations. The best explanation was outgassing. The process that produced a comet’s coma as it heats up. The release of gas can actually nudge the orbit. If that’s what caused the change to ‘Oumuamua’s orbit, it would have to be a comet.

There are still a lot of unanswered questions. We didn’t see a coma, so maybe a journey through interstellar space alters comets in some way. Or perhaps ‘Oumuamua is an asteroid, and there’s some mechanism at work that we’ve never seen before. We might never know — ‘Oumuamua is leaving, and it isn’t coming back.
Astronomers from Harvard University suggest that the interstellar object 'Oumuamua may be an extraterrestrial solar sail from an alien civilization, in an effort to help explain the object's "peculiar acceleration".