The interstellar object known as Oumuamua has been a source of fascination since its discovery in 2017, due to its unique shape and unusual behavior. Some even speculated that it might be an alien spacecraft. But a new study has offered a more sober explanation for the comet’s behavior – the release of hydrogen gas as it warmed up in the sunlight.
What caused the Acceleration?
Researchers believe that ‘Oumuamua was originally a planetesimal – a small object formed in the early stages of planet formation – that was ejected from its original solar system. As it ventured through interstellar space, it was bombarded by high-energy radiation, which converted some of its frozen water into hydrogen gas that was trapped within the rest of its ice.
As ‘Oumuamua passed through our inner solar system and warmed up, the release of the trapped hydrogen gas gave it a little bit of a kick, causing its acceleration. This process, called outgassing, did not cause a visible tail, as is typical of many comets.
The researchers say that their findings offer a simple explanation for ‘Oumuamua’s behavior that does not require any exotic physics or chemistry. They believe that ‘Oumuamua may have started as a water-rich icy planetesimal similar to comets in our own solar system.
The story of ‘Oumuamua, the first visitor from another star system | Karen J. Meech
Just another Object?
Despite the excitement surrounding ‘Oumuamua, researchers say that it is likely just one of many interstellar objects that visit our solar system. In fact, another interstellar object – the comet 2I/Borisov – was discovered in 2019 and behaved more like a typical comet.
The researchers estimate that one to two interstellar objects may be discovered every year in our solar system once a new astronomical observatory being built in Chile begins operations next year. So, while ‘Oumuamua may be the first interstellar object we’ve detected, it certainly won’t be the last.
The discovery of ‘Oumuamua and other interstellar objects offers exciting opportunities for researchers to study the properties and origins of objects from outside our solar system. As our technology and understanding of the universe continue to advance, we may discover even more interstellar visitors in the years to come.