News: The development of a vital instrument PASIPHAE, which will be used in upcoming sky surveys to study stars, is being led by an Indian astronomer.


  • PASIPHAE stands for Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment.
  • It is an international collaborative sky surveying project. Scientists aim to study the polarisation in the light coming from millions of stars.
  • The name is inspired by Pasiphae, the daughter of Greek Sun God Helios.
  • The survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.
  • It will focus on capturing starlight polarisation of very faint stars that are so far away that polarisation signals from there have not been systematically studied.
  • By combining the data, astronomers will perform a maiden magnetic field tomography mapping of the interstellar medium of very large areas of the sky using a novel polarimeter instrument known as WALOP.

Importance of the Project:

  • Since its birth about 14 billion years ago, the universe has been constantly expanding, as evidenced by the presence of Cosmic Microwave Background (CMB) radiation which fills the universe.
  • The Milky Way Galaxy contains a lot of dust clouds that are present in the form of clusters. When starlight passes through these dust clouds, they get scattered and polarised.
  • The PASIPHAE polarimetric map will be used to perform magnetic tomography of the Milky Way Galaxy.
  • That is, it will deduce the 3-dimensional structure of the magnetic field and the dust that resides in our own Galaxy. This map will provide invaluable information for future CMB B-mode experiments searching for inflationary gravitational waves.