What is Green Comet? - UPSC Current Affairs

Context

Recently NASA (National Aeronautics and Space Administration) reported that after nearly 50,000 years a green comet might be appearing near Earth around 2 February 2023.

Probable Question

What do you understand about Green Comets? Explain how comets are formed. (150 words, 10 marks)

About Comets

• These ancient objects are leftovers from the formation of the solar system 4.6 billion years ago.
• According to NASA, as of January 2023, the current number of known comets is 3,743. 
• Composition: Comets are frozen rocky or gas-filled objects made of dust and ice that orbit the Sun. If a comet contains ice material rather than rocky debris, then scientists sometimes call comets dirty snowballs or snowy dirtballs.
• Orbits: Just like other bodies in space, comets also have orbits. 
• Short-period comets: They mostly found a way out in the solar system. Some exist in a wide disk beyond the orbit of Neptune, (the eighth the last planet) called the Kuiper Belt. They take less than 200 years to orbit the Sun.
• Long-period comets: They live in the Oort Cloud, the sphere-shaped, outer edge of the solar system, the most distant region of the solar system, which is about 50 times farther away from the Sun. The comet with the longest known orbit takes more than 250,000 years to make just one trip around the Sun.
• Appearing near Earth:
  • The gravity of a planet or star can pull comets from their homes in the Kuiper Belt or Oort Cloud. This tug can redirect a comet toward the Sun. 
  • The paths of these redirected comets look like long, stretched ovals. They heat up and spew gases and dust into a glowing head that can be larger than a planet”. The remains of dust following this burning up, from a distance, look like a trail of light to humans on Earth. 
  • Comets, therefore, have often been seen giving out blue or whitish light, or even green.
• Characteristics: 
  • Due to their composition, characteristics, and the path they move in, they tend to leave a light “behind them” with long, streaming tails. 
  • Here, the comet itself is green (called the head of the comet) and emits a whitish light behind it (often called the tail of the comet).

Image Source: NASA

About Green Comet

• Green Comet was recently discovered in March 2022 by astronomers in the US.
• The comet has already approached the Sun and is now moving away from the Sun along its own orbit. The orbit indicates that the green comet comes from the Oort cloud.
• The green glow is thought to arise from the presence of diatomic carbon (pairs of carbon atoms that are bound together) in the head of the comet. The molecule emits green light when excited by the ultraviolet rays in solar radiation.
• It is reported that the green comet could be at a distance of 2.5 light minutes from Earth, meaning a “mere” 27 million miles.
• NASA has said that the comet could be visible with telescopes and binoculars, and might even be visible to the naked eye under a clear night sky.

News Source: The Indian Express

https://indianexpress.com/article/explained/explained-sci-tech/green-comet-close-to-earth-details-date-time-8401036/

Frequently Asked Question about Green Comet

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