Exoplanets - Planets Beyond Solar System

What is an Exoplanet?

Exoplanets are the planets that orbit around other stars located outside our solar system. Exoplanets are also called extrasolar planets. All the stars have at least 1 planet revolving around them. Most of the exoplanets discovered so far are located in the Milky way galaxy.

The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. The first confirmation of detection occurred in 1992. This was followed by the confirmation of a different planet, originally detected in 1988. As of 22 June 2021, there are 4,768 confirmed exoplanets in 3,527 planetary systems, with 783 systems having more than one planet.

Aspirants would find this topic very helpful in IAS Exam.

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Why is it Hard to Detect the Exoplanets Directly with Telescopes?

Exoplanets are hard to be detected directly with telescopes as they are close to the stars they orbit. The brightness of stars prevents it from being detected easily.

How do we Detect Exoplanet?

  1. Transit method
  2. Doppler spectroscopy

What is the Transit Method of Exoplanet Detection?

Whenever a planet passes in front of its star, it is called a transit. Whenever a planet transits in front of its star, a small amount of stars light is obstructed. Hence, there will be a reduction in the brightness of the star. Astronomers can detect the change in the brightness of the star, which helps them in evaluating the size of the planet. Astronomers can detect the distance of the exoplanet from its star by studying the time between transits.

What is the Doppler Spectroscopy Method of Exoplanet Detection?

It is an indirect method of Exoplanet detection. This method makes use of periodic shifts in the radial velocity. It analyses the change in the spectrum of the exoplanets parent star. This is also called the Wobble method of detection.

Which is the Closest Exoplanet?

The closest exoplanet is named Proxima Centauri b. It is a planet orbiting the closest star to the Sun, named Proxima Centauri.

How Many Exoplanets have been Confirmed?

Approximately 4,000 exoplanets have been confirmed. These exoplanets were found in 3,096 systems. Out of these systems, 678 systems have more than one planet.

Which is the Least Massive Exoplanet?

The least massive known exoplanet is named as Draugr. To get an understanding of its size, this exoplanet is twice the mass of the moon.

Which is the Most Distant Discovered Exoplanet?

It is named as SWEEPS-11/SWEEPS – 04. It is located 27,710 light-years away.

Which is the Hottest Exoplanet Discovered?

The hottest exoplanet discovered is Kepler – 70b

Which is the Biggest Exoplanet Discovered?

The biggest exoplanet discovered is Kepler – 39b.

Multiple Choice Question

Consider the following Statements?

  1. The brightness of stars prevents it from being detected easily.
  2.  Exoplanets are also called extrasolar planets.
  3. The closest exoplanet is named Proxima Centauri b. 
  4.  Astronomers can detect the distance of the exoplanet from its star by studying the time between transits. This method of detection is called Doppler Spectroscopy.

Which of the following statements are true.

A) 1 alone is true

B) All 4 statements are true

C) Only 1,2 and 3 are true

D) None of the above statements are true.

Answer: C

The least massive planet is known as:

A) Draugr

B) HR 2562 b

C) HIP 65426b

D) Kepler-452b

Answer: A) Draugr

Exoplanets- UPSC Notes:- Download PDF Here

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