Why in the news?

  • The PUNCH mission has captured the image of the solar wind, according to the Principal Investigator of the Mission.

PUNCH Space Mission

  • What is it?:
    • PUNCH stands for Polarimeter to Unify the Corona and Heliosphere. 
    • It is a NASA solar mission designed to study the Sun’s corona and the solar wind as an interconnected system.
  • Launch: Launched by NASA in SpaceX Falcon 9 rocket from California
  • Mission Duration: Approximately 2 years
  • Orbit: Low Earth Orbit (LEO)
  • Key Features:
    • Constellation: Four identical, suitcase-sized microsatellites
    • Imaging technique: Uses polarimetry- measuring the polarisation of light scattered by particles, allowing 3D mapping of the Sun’s outer layers.
    • Data frequency: Captures polarised images every 4 minutes, and unpolarised images every 8 minutes.
    • Operation: The four satellites work together as a single virtual instrument generating a continuous, large-scale visualisation of solar activity.
  • Significance:
    • Provides new insights into solar wind structure and evolution.
    • Improves prediction accuracy of space weather events such as CMEs and solar flares.
    • Enhances protection of communication systems, satellites, and power grids from solar storms.
    • Offers a more comprehensive understanding of the heliosphere, the region influenced by solar activity.

Solar Wind

  • What is it?:
    • The solar wind is a continuous stream of charged particles- mainly electrons, protons, and alpha particles (helium nuclei)- ejected from the Sun’s outer atmosphere, the corona. 
    • These particles flow through the entire solar system at speeds of 250–800 km/s, carrying the Sun’s magnetic field with them, forming what is known as the heliosphere- a vast magnetic bubble that envelopes our Solar System.
  • Origin:
    • Originates from the solar corona, a region with temperatures exceeding 1 million °C.​
    • The particles gain enough energy to overcome the Sun’s gravitational pull and stream outward.
    • Major source regions:
      • Coronal holes: Regions with open magnetic field lines (sources of fast solar wind).
      • Streamer belt near the solar equator (source of slow solar wind).​
  • Composition:
    • Main constituents: Protons (H⁺), electrons, and alpha particles (He²⁺).​
    • Trace elements: Heavy ions such as carbon, nitrogen, oxygen, magnesium, silicon, sulfur, and iron.​
    • The number density near Earth is around 10 protons per cubic centimeter.
  • Effects:
    • On Earth:
      • Interacts with Earth’s magnetosphere, producing auroras near the poles.​
      • During strong solar activity, it can cause geomagnetic storms, which may disrupt satellite operations, communication systems, and power grids (e.g., 1989 Quebec blackout).
    • In Space:
      • Shapes the heliosphere and influences planetary atmospheres.
      • Creates comet tails that always point away from the Sun due to solar wind pressure.