Chasing 'Oumuamua

The interstellar object 'Oumuamua perplexed scientists in October 2017 as it whipped past Earth at an unusually high speed. This mysterious visitor is the first object ever seen in our solar system that is known to have originated elsewhere.

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Credits: NASA/JPL-Caltech

'Oumuamua was too small to appear as anything more than a point of light, even in the largest telescopes. But we know that it must be a highly elongated object because it varied dramatically in brightness over every 7-to-8-hour period. It appeared brightest when its full length faced the Earth (middle image), but dimmed dramatically when it was pointed towards the Earth (left and right images). The brightness variations (represented as squares on bottom row) repeated over and over as the object tumbled through space.

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Credits: NASA/JPL-Caltech

Scientists conclude that interstellar object 'Oumuamua must be very elongated because of its dramatic variations in brightness as it tumbled through space. They also conclude that vents on the surface must have emitted jets of gases, giving the object a slight boost in speed, which researchers detected by measuring the position of the object as it passed by in 2017.

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This animation (annotated) shows the path of the interstellar object `Oumuamua through the Solar System. Unlike all other asteroids and comets observed before, this body is not bound by gravity to the Sun.

It has come from interstellar space and will return there after its brief encounter with our star system. Its hyperbolic orbit is highly inclined and it does not appear to have come close to any other Solar System body on its way in.