Gamma-Ray Burst In Faraway Galaxy Disturbed Earth's Upper Atmosphere

Relevance: GS3 - Science and Technology, Awareness in the fields of Space,

(Source: The Hindu, 21/11/2023 )

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Why in the news?

• Recently, researchers concluded that a significant disturbance in Earth’s ionosphere observed in 2022 was caused by gamma rays from a supernova explosion that occurred around two billion years ago.
• The disturbance was detected by the European Space Agency's Integral space observatory, various Earth-orbiting satellites, and lightning detectors in India.
• Although this particular episode involving a gamma-ray burst did not have any adverse effects on Earth, scientists have suggested that s particularly strong explosion that takes place in the Milky Way could even lead to mass extinctions.

What are Gamma-ray bursts?

• Gamma-ray bursts are extremely intense flashes of gamma rays that constitute the most energetic form of light in the electromagnetic spectrum.
  • They have been described as the most powerful explosions that have been observed in the universe.
• Cause: Gamma-ray bursts are considered to take place either when massive stars collapse into neutron stars or black holes, or during the merger of the neutron stars.
• These cosmic catastrophes can lead to the release of a very large amount of energy.
• Duration: Although they can extend anywhere from a few milliseconds to several hours, they generally last for just a few seconds.
• The gamma rays from the burst that impacted Earth's atmosphere in 2022 had a span of about 13 minutes.
• Energy released: The amount of energy released during the burst can even be more than that emitted by the Sun during its entire 10-billion-year lifetime.
• After the initial burst, an afterglow is found to occur at longer wavelengths i.e. X-ray, ultraviolet, optical; infrared, and radio.

What was the effect of the 2022 gamma burst?

• The gamma-ray burst which occurred almost two billion years ago resulted in a significant disturbance in Earth's ionosphere after traveling through the universe.
  • This burst was determined to be the strongest ever burst of this kind to be recorded.
• The European Space Agency's Integral (International Gamma-Ray Astrophysics Laboratory) space observatory and other satellites observed the disturbance.
  • The effects of the gamma-ray burst were studied using the China Seismo-Electromagnetic Satellite (CSES), or Zhangheng, which was a Chinese-Italian mission launched in 2018.
  • The Electric Field Detector instrument on the CSES helped scientists measure the electric field at high resolution.
• The gamma rays caused a strong variation in the ionosphere's electric field similar to that caused during a solar flare event.
• Instruments located on Earth revealed that the ionosphere was disturbed by the for several hours and that the disturbance reached the lowest layers of the ionosphere.

What conclusions have studies of the event led to?

• Impact of far-off events on Earth: The event showed how even faraway events like the gamma-ray burst which took place 2 billion light years away from Earth could have an effect on the Earth.
  • In comparison, the sun is around 8 light minutes away from the Earth.
  • The disturbance was also found to have even triggered lightning detectors in India.

• Frequency: Scientists have been measuring gamma-ray bursts since the 1960s and it is expected that bursts similar to the one observed in 2022 could reach Earth every 10,000 years.
• Danger: Although scientists have claimed that gamma-ray bursts could have adverse effects on Earth, the burst that was felt in 2022 did not have any such effects on life on Earth.
  • Scientists have suggested that a strong gamma-ray burst originating within the Milky Way and pointed right at the Earth could lead to mass extinctions by subjecting Earth to harmful UV radiation.
  • However, the risk of such an event taking place has been found to be negligible.
• Visibility: Since the disturbance that occurred in the ionosphere was not viewed by anyone on the ground, scientists have not been able to clearly state whether some visible signal would be observable in the sky.

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FAQs

MCQs

Question: A layer in the Earth’s atmosphere called the ionosphere facilitates radio communication. Why?

1. The presence of ozone causes the reflection of radio waves on Earth.
2. Radio waves have a very long wavelength.

Which of the statements given above is/are correct? (UPSC CSE 2011)

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Question: Which one of the following layers of the atmosphere is responsible for the deflection of radio waves? (UPSC CSE 1996)

(a) Troposphere

(b) Stratosphere

(c) Mesosphere

(d) Ionosphere

Question: Consider the following pairs:

1. Electromagnetic radiation
2. Geothermal energy
3. Gravitational force
4. Plate movements
5. Rotation of the earth
6. Revolution of the earth

Which of the above are responsible for bringing dynamic changes on the surface of the earth? (UPSC CSE 2013)

(a) 1, 2, 3 and 4 only

(b) 1, 3, 5 and 6 only

(c) 2, 4, 5 and 6 only

(d) 1, 2, 3, 4, 5 and 6