ʻOumuamua’s top speed was about 85,700 miles per hour (38.3 km/s) relative to the Sun, as measured by NASA’s Hubble and Spitzer telescopes.
What was the acceleration of ʻOumuamua?
ʻOumuamua’s non-gravitational acceleration peaked at 4.9 ± 0.2 × 10⁻⁶ m s⁻² when it was 0.2556 AU from the Sun, according to Micheli et al. (2018).
That’s a tiny push—about half a millionth of Earth’s gravity—but enough to nudge its path. Scientists ruled out solar radiation, drag, magnetic effects, and odd shape geometry before landing on the most likely cause: faint comet-like outgassing that acted like a weak rocket engine.
How close to Earth did ʻOumuamua get?
ʻOumuamua passed within 0.16 astronomical units (AU) of Earth, more than 60 times the Earth–Moon distance.
It had already swung past the Sun a month earlier, skimming just 0.25 AU from our star on September 9, 2017. By the time astronomers spotted it on October 19, it was already moving away and fading fast.
Did ʻOumuamua accelerate away from the Sun?
Yes—ʻOumuamua showed extra speed after its sunward pass, best explained by faint outgassing.
Researchers tested every possible force—solar pressure, drag, magnetic interactions, even the weird geometry of a cigar-shaped rock. Nothing matched the observed trajectory; only a gentle, rocket-like release of gas fit the data. That makes ʻOumuamua behave more like a mini-comet than a pure asteroid.
How far away is ʻOumuamua now?
As of early 2026, ʻOumuamua is roughly 42 billion km (26 billion mi) from the Sun, cruising past the orbit of Neptune.
Even at 1.5 million miles a day it’ll take tens of thousands of years to escape the Sun’s gravity. For perspective, that’s more than 250 times farther than Earth is from the Sun.
Where is ʻOumuamua now?
ʻOumuamua now lies in the constellation Pegasus, drifting toward interstellar space.
Tiny, dark, and moving at more than 16 miles per second, it’s far too faint for any telescope to image today. Astronomers rely on precise orbital calculations instead of pictures.
Does ʻOumuamua rotate?
Yes—ʻOumuamua tumbles in a complex, non-principal-axis spin.
The elongated shape and uneven outgassing can make it wobble like a poorly thrown football. Exactly how many times it flips per hour is still debated because we’ve never gotten a clear image of its surface.
What solar system is ʻOumuamua from?
ʻOumuamua likely originated in another star’s planetary system.
Its hyperbolic orbit proves it wasn’t bound to our Sun. Leading models suggest it could have been ejected from a debris disk or an Oort cloud around a low-mass star, or even a planet-size body in the habitable zone of a red dwarf.
Where is ʻOumuamua from?
ʻOumuamua’s name comes from Hawaiian ʻō- meaning “scout” or “messenger”.
The object’s formal designation is 1I/2017 U1, the “I” standing for interstellar. The Pan-STARRS team in Hawaii spotted it first, so they named it after the Hawaiian word for a distant scout arriving from afar.
When did ʻOumuamua enter the solar system?
ʻOumuamua entered our solar system in early 2017.
It reached perihelion on September 9, 2017 and was closest to Earth on October 14, 2017. By the time astronomers noticed it on October 19, it was already heading outward again.
How was ʻOumuamua discovered?
Robert Weryk spotted ʻOumuamua on October 19, 2017 while scanning for near-Earth asteroids.
Working with the Pan-STARRS telescope on Maui, he noticed an object moving way too fast to be bound by the Sun. Quick follow-ups with larger telescopes revealed its interstellar trajectory within days, turning a routine asteroid hunt into one of astronomy’s biggest “wait, what?!” moments.
When did ʻOumuamua enter the solar system?
ʻOumuamua entered our solar system in early 2017.
One of the great mysteries of the sky continues to mesmerize astronomers. That would be the nature of a strange interloper, ʻOumuamua, that came zooming through the solar system in 2017. Its incredible speed compared to anything we've seen before makes its brief visit all the more remarkable.
