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Comet or asteroid? The mysterious Oumuamua shows why we need a new classification system



Ever since space scientists first discovered the strange, cigar-shaped object called "Ium Oumuamua" in the sky, they've been discussing what exactly it is. Suggestions include an asteroid, a comet, and even an alien spaceship. Now, a study published in Nature suggests that it could actually be a comet ̵

1; but an unusual one.

The intriguing results complement recent discoveries that suggest that it's time to think about the division of asteroids into comets. Gravity keeps our feet on the ground, the moon orbits the earth and the planets orbiting the sun. It is also the main agent controlling the trajectory of comets as they swing through the solar system. It was his laws of gravity that allowed Newton's colleague Edmond Halley to predict the return of the comet, now known as the Halley Comet. The same laws allowed the Rosetta spacecraft to catch and fly the comet 67P / Churyumov-Gerasimenko.

There are non-gravitational effects that can affect the orbit of a comet, but in comparison to gravity they are so weak normally negligible. But in the case of the 1I / Oumuamua object, its orbit is so unusual that non-gravitational effects could play a role in its geometry.

1I /; Oumuamua was first spotted in October 2017. Calculations based on the laws of gravity showed that his trajectory was neither the ellipse of a comet nor that of an asteroid. Instead, Oumuamua appeared to have a hyperbolic orbit (see video), meaning that it was not gravitationally bound to the Sun. This means that it is most likely an intruder outside the solar system. Hence the "1I" part of his name: the first interstellar body.

O Oumuamua happened within 0.25 astronomical units (AU) of the Sun (1 AU is the distance between the Sun and the Earth). As a well-behaved comet, he should have developed a coma and a tail, like ice and dust, evaporating from the surface through a process called sublimation. But despite an organized and concerted observation campaign by the international astronomical community, no trace of coma or tail was seen.

In fact, measurements of its composition showed that it had more in common with asteroids than with comets: the low reflection from its surface indicated that there was little, if any, ice. It also seemed to have organic material that had been altered by cosmic rays – like many asteroids.

In addition to these observations, Oumuamuas was a very unusual shape: although the object was not directly visible, modeling its light curve (how the amount of reflected light changes as an object rotates) suggests that it is long and thin was – more cigar-shaped than the usual semi-rounded appearance of asteroids and comets. This made one more likely to say, "Oumuamua could be more fabricated than a natural visitor to the Inner Solar System, perhaps an extraterrestrial spaceship.

Recent Evidence

So, comets, asteroids, or spaceships? Devaluing the interstellar spaceship – it would certainly have stopped at least to study the signal mixing that emanates from our planet, leaving comets or asteroids as the remaining options. "The same group that published the discovery report from Oumuamua continued to observe the object and collected data from instruments on virtually all major earth-based telescopes in the world, as well as the Hubble Space Telescope.

<figcaption class = "C ($ c-fuji-gray-h) Fz (13px) Py (5px) Lh (1.5 ) "title =" Hubble Space Telescope. NASA "data-reactid =" 59 "> [19659014] Hubble Space Telescope NASA


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