What are Exo-Planets, and how are they detected?

Before getting to Exoplanets detection, I would like to focus on why search for Exoplanets is important. Is it really worth searching? Whether life is also possible outside our solar system is a profound question of all time. If a planet rich with life is to be found, then it will change humankind forever. Apart from this, this question will also answer the most fundamental questions about our existence. This is where Exoplanet detection comes into the picture.

A planet is a body comprising of gas, dust etc., orbiting a star. All planets outside our solar system that revolve around a star are called Exoplanets. Due to glaring bright light from a star, Exoplanets are difficult to detect using just a telescope. To answer this problem, scientists have devised a method for the detection of these distinct planets. Instead of directly viewing these planets through telescopes, which is not always feasible, they look out for the effects these planets have on the stars they orbit.

One way to find these planets is by looking out for unsteady stars. A star about which a planet is revolving tends to wobble. This is due to the mass of the revolving planet. Many planets have been discovered using this technique. But the problem is, only massive planets like Jupyter can have a gravitational impact on its star, which can cause the star to wobble. Smaller planets like Earth have less impact on a star, thus making the unsteady motion difficult to detect. Then how to detect smaller Exoplanets?

Figure 2: Wobbling star due to gravity of exoplanet (Source: )

Keplar detected smaller planets using another technique called a ‘transit method’. A transit is when a planet passes in front of its star and the observer. Due to this transit, there is a small drop in the intensity of the light reaching the observer. Thus making it less bright. A planet revolving around a star will show a periodic dip in light intensity. This can be seen in the below figure,

Figure 3: Change in the light intensity due to transit (Source: )

The primary Eclipse denotes the dip in the intensity of light reaching the observer from the star due to the Exoplanet obstruction. Thus by studying the time interval between consecutive transits, one can classify whether it is a planet or some celestial body. For this research, I have used the output from a similar…

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Source: towardsdatascience.com