October 7, 2022

Lukmaan IAS

A Blog for IAS Examination



THE CONTEXT: An international collaboration of astronomers has identified a curious occurrence of nine stars like objects that appeared and vanished in a small region within half an hour in an old photographic plate.


  • Astronomers collaborating across counties track vanishing and appearing celestial objects by comparing old images of the night sky with new modern one, register unnatural phenomena, and probe deep into such phenomena to record changes in the Universe.
  • Scientists, investigated early form of photography that used glass plates to capture images of the night sky from the 12th of April 1950, exposed at Palomar Observatory in California, USA.
  • They detected these transient stars which were not to be found in photographs half an hour later and not traced since then.
  • Such a group of objects appearing and disappearing at the same time have been detected for the first time in the history of astronomy.
  • The astronomers have not found any explanation in well-established astrophysical phenomena like gravitational lensing, fast radio bursts, or any variable star that could be responsible for this cluster of fast changes in the sky.
  • The scientists are still exploring the reasons behind the observation of these strange transient stars and are still not sure about what triggered their appearance and disappearance.
  • The astronomers are examining the possibility that the photographic plates were contaminated with radioactive particles causing false stars on the plates.
  • But if the observation is proven to be real, another option is solar reflections from reflective, unnatural objects in orbit around Earth several years before the first human satellite was launched.
  • The astronomers who belong to the collaboration Vanishing & Appearing Sources during a Century of Observations (VASCO) have still not sorted out the root cause of the “nine simultaneous transients”.
  • They are now eager to look for more signatures of solar reflections in these digitized data from the 1950s in a hope to find aliens.


  • As the light emitted by distant galaxies passes by massive objects in the universe, the gravitational pull from these objects can distort or bend the light. This is called gravitational lensing.
  • Strong gravitational lensing can actually result in such strongly bent light that multiple images of the light-emitting galaxy are formed.
  • Weak gravitational lensing results in galaxies appearing distorted, stretched or magnified.
  • Although difficult to measure for an individual galaxy, galaxies clustered close together will exhibit similar lensing patterns.
  • Analysing the nature of gravitational lensing patterns tells astronomers about the way dark matter is distributed within galaxies and their distance from Earth.
  • This method provides a probe for investigating both the development of structure in the universe and the expansion of the universe.
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