In October 2017, a discovery made by astronomers changed our view of what is in the deepest parts of space between stars. A long object flew fast through our solar system and scientists rushed to learn more about it.
Scientists gave this comet the title ‘Oumuamua, which stands for “the first to arrive from far” away”—and it did in fact become the first confirmed interstellar object observed here.
What Is ʻOumuamua?
ʻOumuamua (oh-MOO-ah-MOO-ah) translates from Hawaiian as “a messenger from afar coming ahead of everyone else.” It is called what it is called for good reason: it is the first known interstellar object to pass through our Solar System.
Besides its formal name, 1I/2017 U1, it was found by astronomer Robert Weryk at Pan-STARRS, found at Haleakalā Observatory in Hawaii, on October 19, 2017. The thing is, it wasn’t found for another month after its closest flyby past the Sun on September 9. We observed it after it had traveled 33 million kilometers away from Earth and was on its way back to the deepest part of outer space.
Why ‘Oumuamua Is Such A Strange Object
Every aspect of ʻOumuamua made it different than other space rocks.
Length and Width/Thickness: Some say the Bering land bridge was as long as 1,000 meters and as wide as 152 to 196 meters. For this reason, it became much more extended than any other known object in our Solar System.
It was red in color, similar to items from the outer Solar System which may be due to its long-term exposure to cosmic rays.
No Coma: ʻOumuamua did not create a haze (coma) as comets do when they approach a star.
Mysterious Acceleration: It didn’t just drift through space. It sped up unexpectedly. Scientists proposed this was due to outgassing (like comets), but there was no visible gas cloud. Others thought it might be solar radiation pressure, a force acting on its surface.
This mysterious space visitor sparked scientific debate—and here are 10 key facts that uncover its secrets.
Fact 1: It Was the First Confirmed Interstellar Object Ever Detected
‘Oumuamua holds the historic distinction of being the first confirmed interstellar object observed passing through our solar system. Discovered on October 19, 2017, by Robert Weryk using the University of Hawaii’s Pan-STARRS1 telescope, this cosmic visitor was officially designated 1I/2017 U1 by the International Astronomical Union.
The “1I” designation represents the first object in a new category: “I” for Interstellar objects, marking the beginning of humanity’s catalog of visitors from other star systems.
Fact 2: Its Name Carries Deep Hawaiian Meaning
The Hawaiian name ‘Oumuamua translates to “a messenger from afar arriving first” or “first distant messenger.” The name comes from ‘ou (meaning “reach out for”) and mua (meaning “first, in advance of”), with the repetition adding emphasis.
The first character is actually a Hawaiian ‘okina (not an apostrophe), which represents a glottal stop in pronunciation. Before this official name was chosen, scientists humorously suggested calling it “Rama,” after the alien spacecraft in Arthur C. Clarke’s 1973 science fiction novel “Rendezvous with Rama.”
Fact 3: It Has an Extremely Unusual Shape
Oumuamua is extremely elongated—it is about 400 meters long but only about 40 meters wide, which makes it roughly ten times longer than it is wide. Most asteroids and comets in our solar system are either round or oddly shaped, so this cigar-like or needle shape is rare.
The object takes 7.3 hours to rotate, making its brightness change by a factor of 10 per rotation, which is much larger than other solar system bodies usually experience.
Fact 4: It Moved Very Fast
Back in 2017, when ‘Oumuamua was first observed, it was traveling through the universe at a speed of 196,000 miles an hour (87.3 kilometers per second). When it was at its closest point to the Sun on September 9, 2017, New Horizons reached a speed of 87.71 km/s (196,200 mph).
Comets in interstellar space are given an excess velocity of 26.33 kilometers per second (58,900 miles per hour) by explosive structures found there. Its swift and unusual movements made it obvious that this object came from outside the Solar System.
Fact 5: It Showed Mysterious Non-Gravitational
The thing that perplexed astronomers most was the sudden acceleration of ‘Oumuamua after it had traveled near the Sun. Similar to most comets, which speed up because of outgassing, ‘Oumuamua demonstrated no coma or trail, even though it accelerated even further than gravity could account for.
Because of this unusual behavior, scientists started discussing its structure and origin in great detail.
Fact 6: Scientists Searched for Alien Technology Signals
Since ‘Oumuamua appeared to be so special, the team studied it with powerful telescopes run by SETI and the Breakthrough Listen Project to look for any suggestion of technology.
Applying the Allen Telescope Array and the Green Bank Telescope, the scientists studied for tiny transmitters that only produce 0.08 watts or less. Although there was no unusual radioactivity from the object, researchers think ‘Oumuamua is a natural, not artificial, object.
Fact 7 : It is Unique because of Its Reddish Color
‘Oumuamua is reddish in color, just like objects seen toward the edges of our solar system. It is thought that the star’s color came from cosmic rays acting on it for millions of years.
Long-term effects from powerful radiation in the solar system changed the Red Planet, which made it appear red when observed by astronomers.
Fact 8: It Came from the Direction of Vega and Is Heading Toward Pegasus
‘Oumuamua entered our solar system from the general direction of the constellation Lyra, near the bright star Vega. Interestingly, this direction is close to the solar apex—the direction our Sun moves relative to nearby stars—making it the most statistically likely direction for interstellar visitors to arrive from.
After its close encounter with the Sun, ‘Oumuamua is now heading outward toward the constellation Pegasus, following a hyperbolic trajectory that will eventually take it back into the depths of interstellar space.
Fact 9: It May Have Traveled for Hundreds of Millions of Years Before Reaching Us
It is thought that ‘Oumuamua traveled for a very long time around the Milky Way before entering our solar system and that it may have originated on a planet more than a billion years ago.
The trip for the object in the cold, dark void of space between stars would have been completely isolated, with nightmarish cold and no nearby stars for warmth or illumination. Just a tiny moment of its total journey occurs when comets pass through the solar system.
Fact 10: Similar Objects May Visit Us Regularly, But Most
Go Undetected
Astronomers estimate that interstellar objects like ‘Oumuamua may pass through our solar system approximately once per year, but most go undetected due to their small size, high speed, and the limited time window for observation.
This suggests that interstellar space is filled with debris from other star systems—remnants of planetary formation, fragments of destroyed comets, and ejected asteroids that wander the galaxy.
‘Oumuamua’s discovery has led to improved detection methods and increased vigilance for similar cosmic visitors.
The Legacy of Our First Interstellar Messenger
‘Oumuamua’s brief visit to our solar system opened humanity’s eyes to the dynamic nature of interstellar space and provided our first direct encounter with material from another star system.
While many questions about its true nature remain unanswered—whether it’s a hydrogen iceberg, a fragment of an ancient comet, or something else entirely—this interstellar messenger has forever changed our perspective on what exists in the space between stars.
The discovery has led to proposed missions like Project Lyra, which could potentially catch up to ‘Oumuamua for closer study within 26 years, and has improved our methods for detecting future interstellar visitors.
Final thoughts
ʻOumuamua seemed to enter our sky quickly, mysteriously and in a way that was very different from anything we had experienced. Because of its odd shape, sudden speed increases and origin, people had questions and arguments about the universe.
Having been the first interstellar object to arrive in our solar system, it started a new era in space exploration and motivated missions such as Project Lyra. Even though its real nature is unclear, ʻOumuamua gives evidence of how much more there is to explore in the universe.
FAQs
What is the interstellar visitor to our solar system?
A mysterious object from beyond the stars, discovered in 2017.
Is interstellar space in our solar system?
Interstellar space begins where the Sun’s magnetic bubble, or heliosphere, ends. Surprisingly, part of our solar system already lies beyond this boundary.
Where is Oumuamua now in the solar system?
Asteroid 1I/2017 U1 (‘Oumuamua) is currently located in the constellation Pegasus at Right Ascension 00h 01m 18s and Declination +24° 36′ 29″.
What was the first man-made interstellar object?
Voyager 1 is in a new region of space, broadcasting an unusual noise that allows scientists to find out information about conditions such as temperature, density and magnetic fields.
Why is it called interstellar space?
Interstellar space lies between the Sun’s heliosphere—a huge bubble of charged particles from the solar wind—and the astrospheres of other stars.
