Oumuamua Comet Discovery

Why in news?

Scientists solved the mystery of the small, dark red cigar-shaped object that shot across cosmic neighbourhood late last year.

What is Oumuamua?

Oumuamua - Hawaiian for “a messenger from afar arriving first”, was first spotted on October, 2017.
When it was spotted near the Solar System, astronomers were puzzled to classify the object in space, recently scientists discovered that this object is to be a comet.
When it was discovered, the oddly-shaped, about 800-m-long ‘Oumuamua was racing through space.

It was dark and faint, with no visible ‘coma’ (atmosphere of dust and gas around a comet’s core) or ‘tail’ (elongated cloud that points away from the Sun) signature identifiers of comets as they approach the inner Solar System.

How astronomers found the object to be a comet?

Comets are icy chunks of frozen gases, space rock, and dust, It has fascinated humankind for over 2,000 years.
The absence of a visible tail in the case of ‘Oumuamua had initially led to its being classified as an asteroid.
Scientists discovered the object last year, has shown that comets do not necessarily vaporise and light up as they get close to the Sun.
The object’s spectrum (i.e. the colour of the light it reflects) is very similar to the Solar System comets, This supports it’s identification as a comet.

How Oumuamua differs from other comets?

Oumuamua’s nucleus is probably similar to comets of our Solar System, although some aspects have to be different.
The dust grains have to be larger than typical for other Comets, which could be a reason for the absence of the characteristic cometary tail.
The tail we see in comets is typically made of fine dust lifted off the nucleus and dragged away by the emitted gas.
In the case of ‘Oumuamua, the dust is not visible because it’s made of larger grains, that are too heavy to be lifted off by the gas.
The gas itself is actually very difficult to detect, because the specific molecules composing it (water, CO and CO2) are difficult to see in optical images.

What are the insights from this findings?

There isn’t a lot of information about ‘Oumuamua, but the discovery provides exciting insights into the chemistry of objects born in other solar systems.
The lack of visible tail and activity makes objects harder to see, because they appear less bright.
If an object is active, the dust around it contributes to the overall brightness, making the object also easier to discover.
It has happened a few times that an object that looked asteroidal at the time of discovery was then noticed to have a coma or a tail, and therefore reclassified as a comet.
But once it has been discovered, the indirect method used to identify comets would prevent faulty classifications.

Source: The Indian Express