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The strange interstellar object that crossed our solar system in 2017 continues to surprise scientists
The visitor was named by astronomers Oumuamua "Messenger from afar who arrives first" in Hawaiian.
The elongated object was discovered last October by astronomers working on the Pan STARRS continuous sounding system at the University of Hawaii.
Oumuamua did not have the characteristic tail that defines comets and was originally classified as the first interstellar asteroid .
But the identity of the visitor has turned out to be much more complex.
"It must be a comet"
A team of astronomers led by M arch M icheli of the European Space Agency ( ESA), made high precision measurements using terrestrial instruments and the space telescope Hubble .
Micheli and his team discovered that the object was deviating slightly from the path it would follow if it was only affected by the gravity of the Sun and planets. Comet Hale Bopp with its tail of ice and dust. When the comets approach the Sun, the heat melts and vaporizes part of the ice. Asteroids, on the other hand, do not normally have tail because they remain solid even in the vicinity of the Sun. "SPL
" We unexpectedly discovered that Oumuamua was not slowing as fast as it should be alone under the effect of gravitational force "senior author of the study published in the newspaper Nature .
"We tested many plausible alternatives and m to achievable is that Oumuamua should be a comet and that gases emanating from its surface cause small variations in its trajectory "said David Farnochhia, NASA's Jet Propulsion Laboratory.
Comets contain ice that goes from solid to gaseous when it is heated by the Sun, dragging dust from the surface to create a diffuse atmosphere and sometimes a tail.
However, the team has still not detected dusty materials, so scientists believe that Oumuamua had to liberate r that small amounts of dust
Comets vs. asteroids
Comets and asteroids share certain characteristics.
The two orbit the Sun, follow unusual trajectories and are remnants of the materials that formed the Solar System
Oumuama will not come back. The comet is fast enough to escape the gravitational pull of the Sun and free itself from the solar system. / SPL The greatest difference is the material which composes them . While asteroids are composed of metals and rocks, comets are composed of ice, dust, rock and organic compounds.
For this reason, when comets approach the Sun, heat melts and vaporizes part of the ice. Comets or cometary hairs are clouds of gas or dust that surround the comet in a halo that expands as the sun forms the characteristic tail.
Unlike comets, asteroids normally ] have no tail since they remain solid even near the Sun.
However, some asteroids have been detected that acquire sporadic tails when they eject clouds of gas and dust after being hit by other asteroids.
Some scientists also believe that asteroids formed much closer to the Sun, where it was too hot for ice to remain solid, while comets formed in a distance larger than the Sun which allowed them to remain frozen .
Key Information
"Oumuamua is not the only case where the distinction between comets and asteroids has not been or clear," says Sara Russell of the Natural History Museum of London
"We find comet-like objects in the main asteroid belt", a region of the solar system between the orbits of Mars and Jupiter.
Being the first visitor of another solar system, a comet can give us more information about the formation of planets .
"Comets probably formed in the outer regions of other planetary systems, instead they can escape the gravity of their star and enter interstellar space more easily than they can. an asteroid, "explains Russell.
" Oumuamua and other interstellar travelers who ultimately visit our solar system can potentially give us great clues about the nature and composition of other planetary systems. " objects can show us if our solar system is unique or […] in our galaxy. "
Observations
Oumuama was observed by powerful ground telescopes and was last seen by Hubble early 2018.
Astronomers will continue to analyze these observations, but we will never see Oumuama again.
In September, the comet passed near the Sun at a speed of 315,400 k ilometers per hour .
The comet is fast enough to escape the gravitational pull of the Sun and finally will leave our Solar System.
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