Since its discovery, astronomers have spent considerable time unraveling the origins of this mysterious object.
In October 2017, astronomers detected an unexpected visitor in the Solar System: a cigar-shaped asteroid approximately 100 meters in diameter traveling towards the Solar System from the direction of the constellation Lyra at a speed of about 26 km/s, nearly perpendicular to the ecliptic plane.
This high speed and significant inclination indicate that it could not be an inner Solar System object, but rather originated from a distant star system. This was the first time humans identified an object from outside the Solar System within our Solar System. Because this object was discovered from an observatory in Hawaii, scientists from the International Astronomical Union named it ‘Oumuamua, which means “first messenger” in the Hawaiian language.
Further studies revealed no signs of cometary activity, leading to its reclassification as an asteroid.
‘Oumuamua was discovered on October 19, 2017, by Robert Weryk from the Department of Astronomy at the University of Hawaii using the Pan-STARRS telescope at the Haleakala Observatory on the island of Maui, Hawaii.
The Pan-STARRS program is dedicated to monitoring near-Earth objects. This program can locate potential near-Earth objects by comparing images of the same region of the sky taken at different times. When Robert Weryk noticed a suspicious point of light on his computer, he was not overly excited, as discoveries like this are quite common.
He reviewed the data as usual and checked previous data from a few days earlier, only to discover that this point of light had actually appeared twice but had been overlooked during data processing. Using this information, he quickly calculated the object’s trajectory and was astonished to find that it did not have an elliptical or parabolic orbit like typical near-Earth objects, but rather a hyperbolic trajectory. This meant that this point of light was not bound by the Sun’s gravity and was traveling through the Solar System at super high speed, never to return.
Plotting its trajectory clearly indicated that it could not have originated from the Solar System; instead, it must have formed in another star system.
Recognizing that this could be a very significant and rare discovery, Robert Weryk promptly reported this information to the International Asteroid Center. As soon as ‘Oumuamua was discovered, it sparked immense interest and curiosity among scientists and the public worldwide.
What exactly is it? Where did it come from? Is it related to extraterrestrial civilizations? To clarify these mysteries, scientists conducted extensive observations and analyses of ‘Oumuamua using various telescopes and instruments.
However, as ‘Oumuamua moved away from Earth, it quickly faded from view and became increasingly difficult to observe. Just two months after its discovery, ‘Oumuamua was no longer visible even with the most sensitive ground-based telescopes.
During the limited observation period, scientists gathered some data and information about ‘Oumuamua but also encountered several unexplained phenomena and inconsistencies.
These phenomena and inconsistencies have sparked the imagination and creativity of scientists, giving rise to bold and controversial hypotheses and speculations. One of the most prominent and widely discussed hypotheses is that ‘Oumuamua could be an alien spacecraft or a type of solar sail (light sail). This hypothesis was proposed by scientists Shmuel Biali and Avi Loeb from the Harvard-Smithsonian Center for Astrophysics.
‘Oumuamua has an unusually elongated shape, an irrational ratio for an asteroid, but with the structure of a spacecraft, it becomes very reasonable to minimize damage caused by interstellar dust.
According to precise measurements of ‘Oumuamua’s trajectory by the European Space Agency and other organizations, they found that ‘Oumuamua experienced a weak and continuous additional acceleration as it departed the Solar System. This acceleration could not be explained by known non-gravitational effects from cometary activity, as ‘Oumuamua showed no signs of outgassing or a comet tail.
Shmuel Biali and Avi Loeb believe that this additional acceleration could come from sunlight, meaning that ‘Oumuamua might be an object that can be propelled by sunlight, similar to the solar sails created by humans. Solar sails are a technology that uses the thrust generated by sunlight to propel a spacecraft through interstellar space.
Although sunlight has no mass, it does carry momentum, and when it strikes an object, it imparts a very small momentum to that object. If the object is light enough and large enough, this impulse can create significant acceleration.
The Indian government has previously launched missions powered by solar sails to assist communication satellites in 1992 and 2003. The Japan Aerospace Exploration Agency (JAXA) successfully launched the new spacecraft IKAROS equipped with a solar sail in 2010 to study Venus and the Sun. Since then, NASA and the non-profit research organization Planetary Society have successfully launched solar sail-equipped spacecraft into low Earth orbit.
Light sails are considered a promising technology for interstellar travel because they do not require carrying fuel and can continue to accelerate as long as there is sufficient sunlight.
Avi Loeb calculated that the trajectory of a solar sail with a thickness of just under 1 mm could match observations from Hubble. Observations of ‘Oumuamua’s brightness variation also indicated that ‘Oumuamua is a very elongated and narrow object, with a long-to-short axis ratio of 5:1 or even greater, resembling a light sail to some extent.
Therefore, Shmuel Biali and Avi Loeb argue that ‘Oumuamua may not be a natural object. If ‘Oumuamua is indeed an alien spacecraft or a type of solar sail, where did it come from? How did it enter the Solar System? What is its purpose? These questions have generated immense curiosity within the scientific community and the public. However, since ‘Oumuamua has moved beyond our line of sight, astronomers have lost the opportunity for further observation and discovery.
Based on ‘Oumuamua’s speed and direction as it entered the Solar System, scientists infer that it may have come from a star system approximately 20 light-years away in the direction of Cetus – a star system containing four red dwarf stars, two of which have been confirmed to have planets orbiting them.
Many conspiracy theorists speculate that if ‘Oumuamua was indeed launched from this star system, it could have taken millions, even billions of years to reach us. During this long journey, ‘Oumuamua may have encountered various risks and obstacles, such as solar winds, cosmic dust, and micro-meteoroids. These factors could affect the structure and function of ‘Oumuamua, rendering it unable to operate normally or transmit signals. It is also possible that ‘Oumuamua itself is a passive probe or beacon that only activates or sends signals when near certain targets.
Even without finding any traces of extraterrestrial life, there remains the possibility that we will uncover valuable scientific results.
In any case, ‘Oumuamua presents us with a rare opportunity and challenge to contemplate the possibilities and diversity of celestial bodies and life beyond the Solar System. ‘Oumuamua also makes us realize that our understanding of the Solar System and the universe is still very limited and one-sided, and we need more observations and explorations to expand our vision and knowledge. Perhaps in the near future, we will encounter ‘Oumuamua or similar celestial bodies again. Thus, the question may still arise: Is ‘Oumuamua an artificial object or a natural celestial body?
