Unraveling the ‘Oumuamua Mystery: Is This an Alien Spaceship or Natural Phenomenon?

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Mysterious ‘Oumuamua Comet Unravels its Crowd-Captivating Unusual Riddle!

In 2017, something really cool and special happened. Astronomers spotted a mysterious comet they called ‘Oumuamua that came from outside of our solar system! It had an unusual look, with its shape being between a cigar and a pancake, and it was way too small to be an ordinary comet. That’s why all the scientists (and many regular people) were so excited about it.

Astronomers were very confused because a comet was traveling away from the Sun in an unusual way, even though it shouldn’t have been. Some people said it was a spaceship from another planet! But now scientists at University of California Berkeley and Cornell University think the strange path can be explained by the comet releasing hydrogen gas when it’s warmer near the sun.

‘Oumuamua was really special compared to other comets we known about in our solar system. It was so small that the sun’s gravity made it move in an unusual way because of a tiny little push from some gas from the ice on its surface.

Most comets are like dirty snowballs that move around in the outer space, close to our sun. When sunlight hits a comet, it releases water and other particles– which create a bright halo or cloud around the comet, often with long tails of dust and gas coming off too. The released gases act as rockets on a spaceship to give the comet a little push that changes its route from how most other things in space move around like asteroids and planets.

When astronomers first saw ‘Oumuamua, it was too far away and too small to have a gas or dust cloud around it (like comets do). This made people curious about what this object could be. Did it contain trapped hydrogen gas? Was it a giant snowflake drifting in space pushed by the sun’s light? Could it be a spaceship from another planet? Maybe created by an advanced species? All are possible theories but we don’t yet know for sure.

Jennifer Bergner, a professor at UC Berkeley who looks into the chemical reactions that happen on icy rocks in space, thought that all this might have a simpler explanation. She talked about it with her friend Darryl Seligman and they decided to experiment and check if it was correct. Now he works at Cornell University funded by the National Science Foundation.

Scientists were wondering if a comet travelling through space could get cooked by radiation, forming hydrogen gas. Then, when the comet enters the solar system and warms up, all of that trapped gas could push it forward at a very fast speed! This could help explain why some comets move faster than usual due to something other than gravitational pull.

Surprisingly, she discovered that experiments in the 1970s, 1980s, and 1990s have shown that when ice is bombarded with powerful particles like cosmic rays, it produces a lot of molecular hydrogen (H2) and locks it inside the ice. Amazingly, these cosmic rays can even penetrate deep into the ice – so much so that they convert up to one-fourth of the water into gas!

Scientists found that a huge asteroid called ‘Oumuamua was able to move in an accelerated way, even though it was very small for an asteroid. This different behavior is likely caused by the thin gas shells around it reacting to the acceleration, whereas the same wouldn’t happen with bigger asteroids which don’t have thin enough shells.

Astronomers saw a reddish comet in the sky which was super small, so they couldn’t measure its exact size. However, they guessed it was about 115 by 111 by 19 meters based on its brightness. All of the comets we’ve seen so far vary in size from 1 kilometer to hundreds of kilometers wide!

Seligman said that Jenny came up with an awesome idea: it was a way to explain what’s happening to comets traveling through space. All the other ideas people had before were kinda goofy and didn’t quite make sense, but this one does! This week, Bergner and Seligman wrote a paper about this idea and published it in a journal called Nature. When they started working together on the paper, both of them were doing postdoctoral studies at the University of Chicago.

Uncover Ancient History with Comets

Comets are chunks of ice that were created a very long time ago, 4.5 billion years ago, when our solar system was just starting out. Astronomers use them to learn about what the environment was like during that ancient period. Also, comets from outside our solar system can tell us about other stars with planet-forming disks around them!

According to Bergner, comets can show us what our solar system looked like in ancient times when it was just starting to form. By studying comets, we can take a look at how the solar system used to look.

There are comets located far away in other planetary systems. Some of these comets have been kicked out of their orbits because of gravitational forces caused by nearby objects – this has also happened in our own solar system! From time to time, some of these ‘rogue’ comets fly into our own system and it provides us a great chance to learn more about how planets are formed in those faraway places.

Seligman said that comets and asteroids in our solar system can tell us more about planets than the actual planets. He also believes we can learn more about other distant worlds from interstellar comets rather than analyzing the planets there. In the past, astronomers had studied what they could discover by not seeing any interstellar comets in our solar system.

Something called ‘Oumuamua arrived.

In October 2017, on the island of Maui, scientists at The University of Hawai’i used their telescope known as the Pan-STARRS1 and noticed a space object they thought was either an asteroid or a comet. As they observed it more closely, they realized it’s orbit was tilted and it moved really fast; actually 87 kilometers per second! Because this is much faster than what we usually see in our solar system, the scientists gave it a Hawaiian name ‘Oumuamua which means “A messenger from afar arriving first”. This interstellar object was the very first to be seen in our solar system that wasn’t a dust grain like most other ones found. In 2019, another interstellar object called 2I/Borisov was discovered with similar characteristics to an average comet.

Scientists looked closely at ‘Oumuamua with their telescopes and found out that it had already gone around the sun and was now leaving our solar system.

Because ‘Oumuamua’s brightness changed quickly and looked strange, scientists guessed that it was stretched out with its ends flipping around. Also, it accelerated away from the sun more than normal asteroids, which is what comets usually do when they’re near the sun. When a comet passes, gases and dust come off of their surfaces and make a bright gas cloud around them with two tails-one tail goes in one direction while the other comes out backward because of light pressure. Other things like organic materials and carbon monoxide can be released too.

Unraveling ‘Oumuamua’s Mystery

Astronomers looked for comets, molecules, and dust around ‘Oumuamua, but found nothing. Calculations showed that the Sun’s energy hitting the comet is too small to make water or organic compounds come off the surface. The only way to match what was seen was with special gases such as hydrogen, nitrogen, or carbon monoxide (CO) which can move faster given the right amount of sunlight.

Seligman said that we were very surprised to find out about a comet in our solar system that didn’t have any dust around it. He also mentioned how the strange force that influenced it was not caused by gravity.

People guessed what molecules were in the comet that may have caused it to speed up. Seligman wrote a paper saying, if the comet was made of solid hydrogen – like an iceberg – it would give off enough hydrogen vapour when close to the sun to make its orbit change. The same thing might happen if it was made of solid nitrogen or carbon monoxide.

Astronomers had difficulty understanding what could cause solid objects made of hydrogen or nitrogen, which have never been spotted before, to form. They also couldn’t figure out how these bodies of H2 gas could stay alive in space for up to 100 million years.

Bergner believes that a gas released from frozen ice could be enough to propel ‘Oumuamua forward. She is both an experimenter and a researcher and she studies how really cold ice (which is 5 – 10 degrees Kelvin, which is the temperature of space) reacts with particles and radiation found in space.

When she searched through past publications, she found experiments that showed how particles like electrons, protons and heavier atoms could turn water ice into hydrogen gas. The fluffy parts of a comet can also hold onto this gas in small bubbles. As the heat from the sun touches it, the snow-like structure changes and forces out these pockets of gas. Scientists figured out that as comets get closer to the sun, they release enough hydrogen gas to influence the movements of smaller comets such as ‘Oumuamua.

According to Bergner, this suggests that ‘Oumuamua is basically a typical comet from outside of our Solar System that has endured lots of changes. This theory makes sense when you compare it to comets and asteroids here in our Solar System. In addition, this might explain why there was no dust visible around ‘Oumuamua.

Seligman explained that the dust in the ice wouldn’t come out when you start rearranging the ice and allowing the H2 gas to be released. So, you’re not actually getting rid of the dust.

Seligman said that ‘Oumuamua’s acceleration had shown that it was a comet. Since 2017, he and Bergner have found six other small comets which seemed to have no dust or gas clouds around them. This is called “dark” comets and they demonstrate there’s lots of stuff we don’t yet know about small objects in the solar system. Even though hydrogen is not the cause of these dark comets’ accelerating powers, they are still important.

Japan’s Hayabusa2 mission recently gathered samples from the asteroid Ryugu. Now their next target is a special dark comet called 1998 KY26 which wasn’t recognized as a comet until last December.

Jenny had a good thought about the hydrogen which was trapped. Nobody had ever figured it out prior to her! We think that definitely has to be correct because of the other dark comets in our solar system. Water is found a lot on comets, not just ours but many others too. If a water-filled comet goes into the Oort cloud or sent out into space, we’ll get ice with bits of H2 gas in it.

Scientists think that comets close to the Sun could form hydrogen gas, just like icy planets exposed to bright radiation. This will be proven if they can observe hydrogen coming out of comets from far away Oort cloud. They’ll need to look at the long-period comets which have been hit by cosmic rays.

The Rubin Observatory Legacy Survey of Space and Time, or LSST for short, will be able to detect a lot more interstellar comets and dark comets. Astronomers can use these to find out if hydrogen gases coming from outer space is normal. The survey will take place at the Vera C. Rubin Observatory in Chile and should begin sometime in early 2025. It is predicted that there will be one-three interstellar comet sightings each year, such as ‘Oumuamua or Borisov which have a easily detectable comas.

Jennifer B. Bergner and Darryl Z. Seligman wrote an article called ‘Acceleration of 1I/’Oumuamua from radiolytically produced H2 in H2O ice’, which was published on March 22, 2023 in Nature. Jennifer was given a grant from NASA Hubble Fellowship while Darryl received grants from the National Science Foundation (AST-17152) and NASA (80NSSC19K0444, NNX17AL71A). The article talks about establishing human scleral fibroblasts-seeded collagen matrix and its related mechanical properties.