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Oumuamua : interstellar object

What is Oumuamua?

We all know that our solar system consists of eight planets and their satellites. Between the area of planet Mars and Jupiter, there is an asteroid belt and at the edge of the solar system, there is a disk of asteroids which we call Kuiper Belt and the objects in the Kuiper Belt are called Kuiper Belt Objects (KBO). Sometimes, some guests enter our solar system from the outer solar system and we do not even know about those objects. But, some time ago, scientists detected a Cigar shaped object which was new even for them. Because, it was not a member of our solar system, it had come from another solar system and entered ours. At first it was named as C/2017 U1 PANSTARRS but later named as Oumuamua. The meaning of Oumuamua suggests “Messenger from a far who arrives first.”


That was a day of October 19, 2017. A telescope which is a group of telescopes named Pan-STARRS1 detected a strange object which trajectory was different from the other celestial objects in our solar system. That is why the name of the object was kept C/2017 U1 PANSTARRS. But later, the name was changed and it was kept Oumuamua which means – a messenger which arrives first from a long distance.

Asteroid? Comet??…

An asteroid is that object which is almost round in shape or has an usual shape. They are normally located in the area between the planets Mars and Jupiter. Some other asteroids also come from Kuiper Belt.
Like that, a comet is that object which mainly comes from Kuiper Belt. They get vaporized and form a large tail as they come closer to the sun. They are mainly formed by icy rocks and dusts.

But what was that object? Scientists did not understand that object at that time as it was too strange for them. The cigar-shaped object was unusual. At first, the scientists thought that, it was nothing but a comet. But, they saw that the surface of that object was not vaporizing due to solar radiation. That means, the object might be made of rocks or some metals. That is why, it was considered as an asteroid not a comet.

The dimension ratio of Oumuamua is 1:10. That means, the length of Oumuamua is 10 times greater than the breadth, which is also a proof of having its shape as cigar. It also changed its position rapidly with its own axis. There are no other objects in our solar system like this. In our solar system, there are no other objects detected with dimension ratio greater than 3:1. That means, in our solar system, the objects dimension ratio are less than or equal to 3:1. So, this object cannot be a part of our solar system. It must enter from another solar system.

The speed of Oumuamua was also very astonishing. It was not affected by gravitational field of the sun. Its speed was sufficient to escape the gravitational field of sun. By analyzing with orbital mechanics, the scientists got that the orbit of Oumuamua was hyperbolic. According to Kepler’s law, all planets orbit the sun with their own elliptical path. The path also depends on its eccentricity. If eccentricity of a planet is zero, then the orbital path will be perfectly circular as our satellite moon. But as the eccentricity increases, the path becomes elliptical. If the eccentricity is greater than 1, then it follows a hyperbolic path. The eccentricity of Oumuamua was 1.2 that means the orbital path of Oumuamua is quite hyperbolic. That is why, scientists said that Oumuamua will not pose a problem for us. The hyperbolic path will lead it to the outer solar system.


Here, some questions should arise. Why did it come to our solar system? What was the reason behind its intense speed? Why was it in a cigar shape?
Scientists are now searching for these questions. According to some scientists, Oumuamua came from the distant Kuiper Belt, where thousands of asteroids are travelling from one place to another. But as we mentioned earlier, in our solar system, there are no other objects detected with dimension ratio greater than 3:1, it is hard to consider that Oumuamua came from Kuiper belt. Also, this theory does not explain about its intense speed. If that was a part of Kuiper Belt, then how was it possible that it could overcome sun’s gravitational field?

According to some scientists, Oumuamua was a part of any alien spacecraft, through which they were sending us a signal. They were exactly doing the same thing that we have done with Voyager spacecraft. We sent audio recordings with the help of Voyager spacecraft to detect us. May be, the aliens were also giving us a signal to detect them. But the scientists also mentioned that this might not be true, more experiments are being carried out.

According to some scientists, Oumuamua came from Interstellar space. Interstellar space is that empty space (actually empty space is not completely empty. Here “empty” is referred for “free” space) between two solar systems where no planets, stars or celestial bodies exist. During the formation of stars, planets etc, the rest unused bodies kept travelling in that region. Sometimes, for no reason the bodies enter any solar system. Or may be due to collisions between or among any celestial bodies, Oumuamua headed to our solar system with an intense speed and again went out with hyperbolic path.

But why is it in a cigar shape? How was it formed? More experiments will be conducted in future.

Here also a question should arise, “Why are we so interested about Oumuamua?”

Well, Oumuamua is not the only object which has entered our solar system from another place. There are thousands of asteroids head towards our solar system, but we cannot detect them as they were at a distance from us. Scientists detected Oumuamua because it came too close to earth. That is why, the scientists were very excited about this asteroid. Again, as the shape of Oumuamua is very unusual and such kind of asteroids cannot be found in our solar system that is why by studying about its nature we can determine also the nature of that solar system from where it came. That asteroid may also carry some alien life in the form of virus or bacteria, so by studying them we can also determine some new life forms.

Now, Oumuamua is headed towards the outer solar system. If this speed remains constant, then it can be predicted that in about 2022, it will pass Neptune’s orbit. We may not be able to know everything about Oumuamua, but it may open a door for us to travel through the Interstellar space.

Mostafa M. Hassan

About Author: Mostafa M. Hassan has a total work experience of 10 months in STEM Learning. He is a Program Implementation Associate.

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