On October 19, 2017, telescopes picked up a mysterious celestial object with an odd, elongated shape that moved like a comet but without the tail. It baffled astronomers what it could possibly be, but some believed that it is an object sent by intelligent life.
This mysterious interstellar object was named 'Oumuamua,' meaning 'a messenger from afar arriving first' in Hawaiian. But a new study revealed that this comet-like object could be different from what everyone thought it is. Scientists from the University of Chicago and Yale astronomers explained this phenomenon with interesting scientific implications.
Not an Alien, but a Frozen Iceberg of Molecular Hydrogen
Researchers debunked the belief that it is an alien, saying that the mysterious interstellar visitor is a frozen iceberg of molecular hydrogen.
Incoming UChicago postdoctoral fellow who authored a paper in Astrophysical Journal Letters, Darryl Seligman, explained that this gives light to every mysterious property about it, and if ever this new theory is correct, it is most likely that the galaxy is full of similar objects.
Oumuamua made headlines in 2017 as the first interstellar object to visit the solar system. But telescopes were not able to pick it up immediately, but its trajectory and the way it accelerated suggest that it came from outside the galaxy.
Science news outlet Phys.org reported that it does not have a cometary tail, unlike the ones typically seen in comets with charged dust particles in the outflow. However, in 2019, Seligman and colleagues at Yale University and Caltech showed that it has an outflow but is merely invisible to the telescopes. From that idea, they checked what substance could be in the outflow and how much energy it should be getting from the sun at any given time.
"The only kind of ice that really explains the acceleration is molecular hydrogen," Seligman said.
Molecular hydrogen ice is only formed when the temperature is just at a smidge above absolute zero. It neither reflects light nor produces any as it burns up; that is why telescopes could not spot its overflow.
This finding implies that there could be other dark hydrogen icebergs hidden in the galaxy where it can be made.
What's With Its Odd Shape?
Oumuamua has an odd, elongated shape, which, according to Seligman, is caused by being carved continuously by energetic particles found in space and sunlight, which removes hydrogen from the surface. It is like using a rectangular bar of soap that after using it for a few times, it gets smaller and thinner.
The researchers believed that Oumuamua had been meandering through space, untouched for millions of years until it encountered the solar system. It got smacked like a bug in the windshield, said Seligman.
The collision and subsequent intense radiation from the sun fast-tracked the process that formed its unusual shape today. This means that most of its shape have happened while it was fairly close to Earth, Seligman added.