Tag Archives: ‘Oumuamua

Interstellar Object ‘Oumuamua Might Be a Hydrogen Iceberg

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Astronomers discovered our first confirmed interstellar visitor in 2017, naming it ‘Oumuamua, the word for “scout” in the Hawaiian language. Determining what ‘Oumuamua actually was proved a more daunting task. Eventually, astronomers decided ‘Oumuamua was probably a very old comet, but a new analysis suggests it may be a different kind of object altogether — an interstellar hydrogen iceberg. 

‘Oumuamua had scientists scratching their heads because everyone had always assumed our first alien visitors would be comets ejected from another solar system’s Oort Cloud. However, ‘Oumuamua didn’t form a coma or vaporized material as it neared the sun. So, an asteroid? Not so fast — more analysis showed ‘Oumuamua’s course was being nudged by outgassing from its surface. So, that supported the idea that ‘Oumuamua was a very old comet that had lost most of its volatile gases. 

The analysis from Yale astrophysicists Darryl Seligman and Gregory Laughlin admits that a hydrogen iceberg is a rather exotic object to be flying through the solar system, but it would explain all of ‘Oumuamua’s bizarre properties. Hydrogen usually exists as a gas, but it’s possible to freeze it at very low temperatures (around -450 degrees Fahrenheit). Clumps of frozen hydrogen are believed to exist in the centers of dense molecular clouds where temperatures are near absolute zero. Could one of those hydrogen icebergs have floated our way?

Frigid molecular clouds only last a few hundred thousand years before dissipating. However, over that time a cloud could generate a block of hydrogen ice a few hundred meters across. It just so happens that’s about the same size as ‘Oumuamua, which is less than 800 meters long. This could also explain why ‘Oumuamua is cigar-shaped. After a cloud disperses, cosmic radiation would erode the iceberg as it floats through space. Uneven radiation from nearby objects could cause it to become cigar-shaped like ‘Oumuamua. 

‘Oumuamua’s path through the solar system in 2017.

Perhaps the strongest evidence for the hydrogen iceberg theory is that it would explain how ‘Oumuamua changed course after entering the solar system. Comets get a small boost from outgassing but remember: ‘Oumuamua had no visible coma. Its course change could be explained if it was releasing pure hydrogen. That would give it a little nudge, and hydrogen gas would not be visible from here on Earth. 

This all hangs together well, but there’s no way to confirm it right now. ‘Oumuamua is moving too fast for us to intercept as it leaves the solar system. Many astronomers believe other interstellar objects pass through the solar system on a regular basis. It’s just a matter of spotting them. If we see another object like ‘Oumuamua, we may have a chance to test the iceberg hypothesis.

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Was Interstellar Visitor ‘Oumuamua Torn Apart by a Star?

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You might remember ‘Oumuamua, the very first interstellar visitor astronomers ever detected in our solar system. This object is almost certainly not an alien spaceship, but it does have an extremely bizarre elongated shape. Now, researchers from the Chinese Academy of Sciences and the University of California, Santa Cruz have put forth a hypothesis that could explain how ‘Oumuamua got to be so weird

Astronomers spotted ‘Oumuamua in October 2017 when it was already on its way out of the solar system. Its orbit and high speed confirmed it could not have come from any source inside our solar system, but it was impossible for any spacecraft to catch up to the mysterious space rock. Long-distance observations confirmed ‘Oumuamua was about 1,300 feet (400 meters) in length and just a few hundred feet wide. The scientific community went back and forth on whether ‘Oumuamua was an asteroid or a comet, eventually settling on a very, very old comet that doesn’t produce a visible coma of vaporized material. 

That didn’t explain how this icy hulk from beyond the stars acquired its spindly shape. The new analysis suggests that ‘Oumuamua could be a result of “extensive tidal fragmentation” in its home solar system. Tidal interactions are the result of high gravity on comparatively small objects. For example, the high gravity of Jupiter causes tidal heating in some of its moons. Tidal interactions also famously ripped comet Shoemaker-Levy 9 into pieces before it collided with the planet in 1992.

The simulations developed for the new study show that tidal stresses from a star’s gravity could fracture an object like a comet or asteroid, imparting enough energy to eject the fragments from the system. The melted chunks would stretch into an elongated shape as they swing around the star. Moving away from the star would allow the fragments to cool and retain that stretched-out shape as they floated into interstellar space. 

‘Oumuamua (center) as seen in October 2017.

This is just a hypothetical simulation, but it would explain more than ‘Oumuamua’s unusual shape. The researchers note that heat diffusion during the tidal interaction would consume large amounts of volatile materials. That could explain ‘Oumuamua’s surface coloration and the lack of a coma. 

It didn’t take long after the discovery of ‘Oumuamua for scientists to spot a second interstellar traveler — 2I/Borisov appeared in the sky in fall 2019, looking like a very typical comet. This is probably just the beginning. With better technology, we’ll find more of these objects, allowing us to better understand their origins.

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Scientists: Sorry, ‘Oumuamua Still Isn’t an Alien Spaceship

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Astronomers have been pondering the nature of our first interstellar visitor ever since its discovery. ‘Oumuamua is bizarre — not only is it from beyond the stars, but it’s also long and cigar-shaped. That led some to wonder if it wasn’t really an alien spacecraft, but past studies of ‘Oumuamua have suggested that it’s just a space rock. Now, a comprehensive analysis from scientists at the University of Maryland and other institutions has ruined our fun once and for all. ‘Oumuamua isn’t an alien spaceship. 

While there have no doubt been alien objects in our solar system before, ‘Oumuamua was the first one we ever spotted. Astronomers at the Pan-STARRS observatory identified ‘Oumuamua in October 2017, but it was already on its way out of the solar system at that point. Its incredible speed and orbital eccentricity meant it could not have come from inside the solar system, but it was moving too fast for anything to catch up and take a closer look. 

It didn’t take long after the discovery for people to start half-jokingly wondering if ‘Oumuamua was an alien ship. Even if we ignore that, it took scientists a few tries to properly identify the object. The initial assumption was that ‘Oumuamua had to be a comet because comets would be easier to eject from the edges of a solar system. However, scientists couldn’t see a cometary tail (or coma) on ‘Oumuamua. After labeling it an asteroid, further analysis of its trajectory found evidence of slight out-gassing. Astronomers finally decided ‘Oumuamua was likely a very old comet. 

‘Oumuamua’s path through the solar system in 2017.

So, why is it definitely not an alien spaceship with a fuel leak or something? The team behind the new study included experts from a variety of fields to create a “big-picture summary” of ‘Oumuamua. They began with its origins, showing that there are several possible mechanisms by which an object like ‘Oumuamua could end up in interstellar space. Its behavior in our solar system, while strange, is also explainable with natural origins. In fact, its path around the sun matches a prediction published by one of the study authors six months before ‘Oumuamua’s discovery. 

‘Oumuamua is strange, but the study concludes there’s nothing unexplainable going on here. Jumping to the conclusion that it’s an alien spacecraft is fun, but the evidence does not support that. Astronomers hope to get a look at more alien visitors in the future. Upcoming instruments like the Large Synoptic Survey Telescope (LSST) will make it easier to spot small objects passing through the solar system. If we can find a few dozen alien space rocks, we might find that ‘Oumuamua is very typical of visitors from beyond the stars.

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Alien Object ‘Oumuamua May Be Smaller Than We Thought

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Scientists have long expected that we would eventually find an object in our solar system that started out orbiting another star. However, no one expected it to be so weird. The alien comet ‘Oumuamua appeared in the sky last year as it tumbled past the sun. From our limited observation time, astronomers have determined ‘Oumuamua is a small cigar-shaped object, but we didn’t know exactly how small until now. When attempting a follow-up observation with the Spitzer Space Telescope, ‘Oumuamua was nowhere to be found. So, it’s either an alien ship that engaged its warp engines or ‘Oumuamua is smaller than we thought.

Sky-watchers first detected ‘Oumuamua in the fall of 2017 using the University of Hawaii’s Pan-STARRS 1 telescope. At that point, it had already curved around the sun on its way out of the solar system. Analysis of ‘Oumuamua’s speed and trajectory confirmed it could not have originated in this solar system. Scientists have pointed to several possible home systems for the object, but we may never know where it started out.

In late 2017, NASA pointed the Spitzer telescope at ‘Oumuamua — or rather, where it should have been. That was about two months after its closest approach to Earth when it should have still been visible to the telescope. The team hoped that Spitzer’s infrared instruments would shed more light on the nature of the probable comet. However, Spitzer couldn’t spot ‘Oumuamua at all.

Previously, astronomers figured ‘Oumuamua could be as long as 2,600 feet (800 meters) along its longest dimension. However, Spitzer should have been able to spot something in that range. So, the non-detection tells us a lot about ‘Oumuamua’s actual size. Using three different models, NASA now projects the object could be as much as 1,440 feet (440 meters) in length. It could also be much smaller — just 320 feet (100 meters). The wide range comes from our uncertainty about ‘Oumuamua’s composition.

‘Oumuamua’s path through the solar system in 2017.

This new stat for ‘Oumuamua jives with the presumption that it’s a natural object. It’s certainly interesting to speculate that it could be an alien spaceship, but that was always an outside chance. NASA believes it’s essentially a small, low-activity comet. The perturbations in its movement are the result of gases leaking from the surface, and the newly established size supports that hypothesis.

If ‘Oumuamua holds any more secrets, they’re likely to remain that way. It will pass out of the solar system in a few years, and it’s already too far away for any telescope to see.

Now read: NASA: Gas Giant Ejected ‘Oumuamua Into Interstellar SpaceOur First Interstellar Visitor May Have a Violent Past, and

NASA’s TESS Spacecraft Captured Amazing Footage of a Comet During Testing

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Harvard Researchers: ‘Oumuamua Could Be an Alien Probe After All

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Our first confirmed interstellar visitor was a tough nut to crack. Scientists puzzled over ‘Oumuamua when it appeared in the sky last year. The classification flipped back and forth a few times before eventually landing on “comet,” but it’s a weird comet. Now, researchers from the Harvard Smithsonian Center for Astrophysics have revived the idea that ‘Oumuamua could be an alien spacecraft.

While we’ve recategorized ‘Oumuamua a few times, we can say with utmost certainty that it came from another solar system. It has an orbital eccentricity of 1.20, which is far past the sun’s escape velocity. Nothing in the solar system could reach that speed naturally without a cataclysmic release of energy that we would have noticed.

‘Oumuamua was already on its way out of the solar system and moving at high speed when we spotted it, so there was no time to build and launch a mission to intercept it. We haven’t even gotten a very good look at the object. Scientists believe ‘Oumuamua is cigar-shaped and up to 120 meters in length. That’s an unusual shape for an asteroid (at least in this solar system) so the discoverers initially categorized it as a comet. Then, scientists looked closer and saw no coma, the cloud of dust and gas that surround a comet when it nears the sun. So, an asteroid? Upon even closer examination, researchers found ‘Oumuamua’s orbit was being nudged by a force consistent with gas release. Currently, ‘Oumuamua is considered a low-activity comet.

The newly released paper (which hasn’t been peer-reviewed yet) suggests another option. What if the small force acting on ‘Oumuamua is not from gas release? The study suggests that ‘Oumuamua could have an odd orbit because it’s an alien space probe with a solar sail. A solar sail is a concept for a low-power propulsion system currently in testing at a number of companies and space agencies around the world. The sail would use the pressure of the solar radiation to propel a craft forward continuously. Over time, a solar sail could reach high speeds, possibly even leaving the solar system.

‘Oumuamua’s path through the solar system in 2017.

The researcher making this proposal are not presenting evidence that ‘Oumuamua actually has a solar sail — there’s no way to know that with current technology. Instead, they seek to demonstrate that it is possible based on what we know of the physics of solar sails and the orbit of ‘Oumuamua. The study concludes that it’s possible that ‘Oumuamua is being dragged along by a solar sail, but that doesn’t necessarily mean it’s an active alien probe.

Researchers scanned ‘Oumuamua back in 2017 to look for any electromagnetic emissions, finding nothing. At that point, they deemed it not an alien ship. The new study suggests ‘Oumuamua could be non-functional debris with a bit of light sail material clinging on. Alternatively, it could be a probe in a low-power mode that we cannot characterize. Unfortunately, we’ll probably never know for sure what ‘Oumuamua is — it’s already long gone.

Now read: Breakthrough Listen Launches Unprecedented Effort to Find AliensNASA: Gas Giant Ejected ‘Oumuamua Into Interstellar Space, and Interstellar Visitor ‘Oumuamua Came From 1 of 4 Nearby Stars

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Interstellar Visitor ‘Oumuamua Came From 1 of 4 Nearby Stars

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Last year, astronomers spotted an object from beyond the stars. There have surely been many interstellar visitors to our humble solar system over the eons, but this is the first one we’ve been able to study as it passed through. ‘Oumuamua is a slender, cigar-shaped comet that could have come from almost any nearby star. However, scientists have pinned down the four most likely origins for ‘Oumuamua.

The scientific community announced the discovery of ‘Oumuamua in late 2017. By that point, it was already on its way out of the solar system after slingshotting around the sun. It entered the solar system going 15.8 miles per second (25.5km/s), and it’s going even faster now. Combined with an orbital eccentricity of 1.20, there’s no doubt it came from another solar system.

The high speed makes it impossible to catch up to ‘Oumuamua, so it’s been difficult to characterize it. Scientists first labeled it a comet, but the lack of a visible coma made everyone think it wasn’t one. Earlier this year, analysis of its path through space confirmed it was outgassing like a comet. It’s just a “mildly active comet.” We also know it’s probably not a spaceship.

Researchers from the Max Planck Institute have used data from the ESA’s Gaia satellite to calculate possible paths for ‘Oumuamua all the way back to nearby stars. The Gaia satellite is a star-mapper with data on some seven million stars. Since stars drift through the cosmos over time, you can’t draw a straight line from ‘Oumuamua to its origin point. However, the team did identify four stars which would have been very close to its path in the last several million years.

All four possible origins are dwarf stars. The one with the closest location and velocity correlation to ‘Oumuamua is HIP 3757. It’s a red dwarf about 81 light years distant. A million years ago, it would have been within two light years of ‘Oumuamua’s path. Next up is HD 292249. It’s a yellow dwarf like the sun and currently sits about 135 light years away. It was within a few light years of ‘Oumuamua’s projected path 3.8 million years ago. The other two stars had potential encounters with ‘Oumuamua 1.1 and 6.3 million years ago, but they didn’t match as closely as the first two.

This analysis is based on the second data set from the Gaia spacecraft. Another release in 2021 should provide velocity data on many more stars, which could lead to a more precise identification of ‘Oumuamua’s origin.

Now read: Breakthrough Listen Launches Unprecedented Effort to Find AliensJapanese Probe Drops Off Robots on Asteroid’s Surface, and NASA: Gas Giant Ejected ‘Oumuamua Into Interstellar Space

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NASA: Gas Giant Ejected ‘Oumuamua Into Interstellar Space

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It has been several months since ‘Oumuamua’s discovery, but scientists are still puzzling over our first interstellar visitor. We’ve determined a few important facts, like it’s not an alien spaceship and it’s sort of cigar-shaped. Bigger questions like where it started out and how it got to our solar system are still up in the air. Researchers from NASA’s Goddard Space Flight Center have used ‘Oumuamua’s composition to speculate on how it left its home system.

It was Oct. 17 of last year when astronomers at the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1) facility spotted what they believed to be a new comet. The object we would eventually come to know as ‘Oumuamua was already rocketing out of the solar system at more than 196,000 mph (315,400 km/h). It also had an orbital eccentricity of 1.20. It was unmistakably alien to our solar system, but it didn’t look like we expected. 

Astronomers were wrong when they initially labeled ‘Oumuamua as a comet. Upon closer observation, there was no coma of evaporating ice and dust around the object. So, it was an interstellar asteroid. This unexpected revelation is what the Goddard team is considering in the new study.

Based on what we know about planetary formation, icy comets accumulate toward the outer edge of a system like our Oort Cloud. They won’t last long toward the inner solar system because they’d just evaporate. It’s much easier to eject an object far from a star than one orbiting closer, so scientists always believed our first confirmed interstellar visitors would be comets. However, ‘Oumuamua appears to be inner solar system material. So, what gives?

‘Oumuamua’s path through the solar system.

According to the Goddard team, there may be something wrong with our models of planetary formation if most interstellar objects are rocky like ‘Oumuamua. We only have a sample size of one so far, so it’s hard to know for certain.

In the case of ‘Oumuamua, the team suggests an encounter with a gas giant is the most plausible explanation for its arrival in our neck of the galaxy. A planet the size of Jupiter would be able to fling an object like ‘Oumuamua (between 30 and 180 meters in length) out of its home system with a gravity slingshot. Scientists around the world will be on the lookout for more objects from beyond the stars. If too many of them turn out to look like ‘Oumuamua, we may have to reevaluate theories on solar system formation.

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