Interstellar objects don’t often visit the solar system, but there are a few notable ones. The first was Oumuamua, which means scout or messenger in Hawaiian, seen in 2017; while the second was the comet 2I / Borisov, the first rebel comet and the second interstellar object.
However, a recently published study claims that the solar system may be visited by interstellar objects more often than scientists previously thought.
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NASA’s Hubble Space Telescope has given astronomers their best glimpse yet of an interstellar visitor – Comet 2I / Borisov – whose speed and trajectory indicates it has come from beyond our solar system.
Interstellar visitors outnumber solar system objects in the Oort cloud
Amir Siraj, lead author of the study, said that before discovering the first interstellar comet, scientists had no idea how many interstellar objects exist in the solar system. The theory of solar system formation suggests that there are more solar system objects than interstellar visitors.
However, the opposite is true because experts have calculated that interstellar objects outnumber objects in the solar system. According to Forbes, this is only true for those objects in the Oort cloud.
Nasa said the Oort Cloud is the most remote region in the solar system, farther than the Kuiper Belt. The Oort Cloud is thought to be a large spherical shell surrounding the planetary system, like a large-walled bubble made of icy space debris the size of mountains. Also, it is believed to contain billions or maybe billions of objects.
Forbes further reported that the study titled “Interstellar objects outnumber solar system objects in the Oort cloud, published in tMonthly notices from the Royal Astronomical Society, suggests that native comets in the Oort cloud could be 10 times more numerous than interstellar comets.
However, these interstellar comets are not easily visible to humans from Earth. One reason could be that the comets that cannot be seen are those near or in the vicinity of Earth.
Another reason could also be the lack of technology to see the objects in the Oort cloud. However, with future improvements and space programs, scientists hope to see this remote region of the solar system up close.
“These results suggest that the abundances of interstellar objects and Oort clouds are comparable closer to the Sun than to Saturn,” Forbes cited, citing astrophysicist Matthew Holman.
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The study of interstellar objects could give indications on the formation of the solar system
Now that scientists have found two interstellar objects, their hunch that the solar system could be crawling with interstellar objects is confirmed. However, according to BBC Future, predicting how often they appear visible from Earth is extremely tricky.
Before Oumuamua and Borisov were detected, a first calculation in 2009 estimated the density of stars in the Milky Way. This includes assumptions that the matter ejected by each star is comparable to the sensitivity of available telescopes. This calculation says the scientists shouldn’t have seen the Oumuamua, but they did.
Siraj said the study of interstellar objects could help scientists unlock the secrets of the formation of the solar system. If the Oort Cloud is indeed dominated by interstellar objects, there must be more debris since the formation of the solar system.
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