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James Webb Space Telescope and its role in exoplanet research UPSC NOTE

 Why in News

  • Astronomers have searched for years for rocky planets beyond our solar system with an atmosphere, a trait considered essential for any possibility of harbouring life. 

  • they finally located one, But this hellish planet, apparently with a surface of molten rock, offers no hope for habitability.

  • Researchers said on Wednesday the planet is a "super-earth", a rocky world significantly larger than our planet but smaller than Neptune, and it orbits perilously close to a star dimmer and slightly less massive than our sun, rapidly completing an orbit every 18 hours or so.

  • Infrared observations using two instruments aboard the James Webb Space Telescope indicated the presence of a substantial, if inhospitable, atmosphere, perhaps continuously replenished by gases released from a vast ocean of magma.

  • The planet, called 55 Cancri e or Janssen, is about 8.8-times more massive than the earth, with a diameter about twice that of our planet. 

  • It orbits its star at one-25th the distance between our solar system's innermost planet Mercury and the sun. 

  • As a result, its surface temperature is about 1,725 degrees C.

  • The planet is probably tidally locked, meaning it perpetually has the same side facing its star, much like the moon does toward the earth. 

  • The planet is located in our Milky Way galaxy about 41 light-years from the earth, in the constellation Cancer. 

  • A light year is the distance light travels in a year, 9.5 trillion km. 

  • Four other planets, all gas giants, are known to orbit its host star.

  • The James Webb Space Telescope (JWST) is a revolutionary observatory launched in December 2021. 

  • Here are its key features that make it crucial for exoplanet research:

  • 1. Infrared Vision: Unlike Hubble Space Telescope which primarily observes visible and ultraviolet light, JWST focuses on infrared wavelengths. 

  • This allows it to see cooler objects like exoplanets that are often hidden by the glare of their host stars in visible light.

  • 2. High Resolution and Sensitivity: JWST boasts a massive mirror and advanced detectors, enabling it to see faint objects in exquisite detail. 

  • This is essential for distinguishing exoplanets from the background and studying their atmospheres.

  • 3. Coronagraphy: JWST is equipped with special instruments called coronagraphs that can block out the light of a star, allowing scientists to directly image the faint light reflected by orbiting exoplanets.

  • 4. Spectroscopy: JWST can analyze the spectrum of light passing through an exoplanet's atmosphere, revealing the presence of various molecules like water vapor, methane, and carbon dioxide. 

  • This information provides clues about the planet's potential habitability.

  • JWST's Role in Exoplanet Research:

  • Discovery of new exoplanets: JWST's ability to detect faint, distant objects makes it ideal for finding new exoplanets, especially smaller, rocky planets in the habitable zones of their stars.

  • Characterization of exoplanet atmospheres: By analyzing the atmospheres of exoplanets, JWST can help determine their composition, temperature, and potential for harboring life.

  • Understanding planetary formation: Studying exoplanets at various stages of development can provide insights into how planetary systems form and evolve.

  • Overall, JWST is a game-changer in exoplanet research. 

  • It allows us to see farther, with greater detail, and uncover the secrets of these distant worlds, bringing us closer to finding another Earth-like planet.

Key differences between gas giants and rocky planets

  • Composition:

  • Gas Giants: Primarily composed of lighter elements like hydrogen and helium, with a small rocky core.

  • Rocky Planets: Made mostly of heavier elements like oxygen, silicon, iron, and magnesium.

  • Size and Mass:

  • Gas Giants: Much larger and more massive than rocky planets. 

  • Jupiter, the largest gas giant in our solar system, is 318 times more massive than Earth.

  • Rocky Planets: Smaller and less massive than gas giants. 

  • Earth is the largest rocky planet in our solar system.

  • Atmosphere:

  • Gas Giants: Thick and extensive atmospheres composed mainly of hydrogen and helium, with some methane, ammonia, and water vapor.

  • Rocky Planets: Can have a wide variety of atmospheres, ranging from very thin (like Mercury) to thick and dense (like Venus) or even absent (like Mars). 

  • The composition of the atmosphere depends on the planet's size, temperature, and geological history.

  • Formation:

  • Gas Giants: Formed further out from the star where it's cooler, allowing lighter elements to condense. 

  • They may have accreted large amounts of hydrogen gas from the protoplanetary disk.

  • Rocky Planets: Formed closer to the star where it's hotter, causing lighter elements to vaporize.

  • They accreted heavier elements leftover from star formation.

  • Surface:

  • Gas Giants: No well-defined surface because the gas giants are fluid down to great depths. 

  • As pressure increases towards the core, the hydrogen gas might eventually turn metallic.

  • Rocky Planets: Have a solid, rocky surface with features like mountains, valleys, and craters.

  • Habitability:

  • Gas Giants: Not considered habitable due to their extreme pressure, composition, and often violent weather patterns.

  • Rocky Planets: Have the potential to be habitable if they are in the star's habitable zone (the region where liquid water can exist on the surface) and have a suitable atmosphere. 

  • Earth is the only known habitable planet so far.


  • Gas Giants: Jupiter, Saturn, Uranus, Neptune

  • Rocky Planets: Mercury, Venus, Earth, Mars



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Learnerz IAS | Concept oriented UPSC Classes in Malayalam: James Webb Space Telescope and its role in exoplanet research UPSC NOTE
James Webb Space Telescope and its role in exoplanet research UPSC NOTE
Learnerz IAS | Concept oriented UPSC Classes in Malayalam
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