A guest from interstellar space - a giant asteroid with a strange shape

Observations have shown that it is one of the most elongated cosmic objects known to science. Calculation of its orbit showed that it originated in a system of planets orbiting another star and not from our solar system. In fact, its length is 10 times greater than its width. This ratio is more extreme than that of any asteroid or comet observed in our solar system.

A large asteroid visited relatively close to Earth and was discovered on October 19. Its uniqueness - it originates in outer space and this is its only passage through the solar system. Besides the official name given to it by the World Astronomical Union interstellar asteroid 1I/2017 U1, the asteroid was nicknamed Oumuamua which means "messenger from afar who arrives first" in the native Hawaiian language. Pronounce it oh MOO-uh MOO-uh.

Observations have shown that it is one of the most elongated cosmic objects known to science. Calculation of its orbit showed that it originated in a system of planets orbiting another star and not from our solar system. In fact, its length is 10 times greater than its width. This ratio is more extreme than that of any asteroid or comet observed in our solar system. A preliminary analysis of its trajectory led the researchers to hypothesize that it is coming roughly from the direction of the bright star Vega in the northern constellation Nebula. However, it took him so long to cruise through space at a speed of 87 kilometers per second, the planet Vega was not at all in this position when the asteroid passed through the area about 300 thousand years ago.

Karen Mitch from the Institute of Astronomy at the University of Hawaii and her colleagues who observed it from a telescope belonging to the Pan-STARRS system for locating near-Earth objects, funded by NASA and determined that the length of the object is about 400 meters, and its brightness changes dramatically. The brightness changes were the first clue that Oumuamua was oddly shaped. Immediately after the discovery, many telescopes turned their gaze to the asteroid and the largest of them - the very large telescope of the Southern European Observatory in Chile.
"When we looked at the light curve data for the asteroid Asteroid, there are five objects (out of 20,000) that have light curves that suggest a mass ratio of one to 7-8. Mitch said. "Our mistakes are very small, so we are sure that he is really extended. We do not know where the axis of rotation is pointing, we assumed that it is perpendicular to the asteroid, therefore there is a projection phenomenon. The ratio of 1:10 is the minimum, it can be even longer."
But in other ways, Oumuamua resembles more familiar objects. "We also found that it is reddish in color, similar to objects in the outer solar system. This means the asteroid is completely inert, without the faintest hint of dust around it,” Mitch said.

These features show that Oumuamua is dense, composed of rock and possibly metals. It has no water or ice and its surface has been reddened by the effect of cosmic radiation over long periods of time.
It is believed to have been in interstellar space for hundreds of millions of years before it randomly encountered our solar system. "For decades there has been a theory according to which there are interstellar objects transiting in the solar system, and now for the first time - We have direct evidence of their existence." said Thomas Zorbuchen of NASA's Science Division in Washington. "This is a history discovery that opens a new window for us to study the formation of solar systems beyond our own."

If indeed it formed under conditions similar to the formation of our solar system, this indicates that many objects of the type of Oumuamua may be found in space. The interstellar visitor may provide the first evidence of this process.

As for the mystery of Oumuamua's elongated shape, Mitch explains that you have many hypotheses. One of them is that during the formation of a planetary system, a collision occurred between bodies that had molten cores. In such a situation, material was ejected and then froze in an elongated shape. Another team member estimated that a supernova explosion near the solar system from which the asteroid came caused its strange shape."

For information on the NASA website