Context: The National Aeronautics and Space Administration (NASA) is set to launch its latest solar mission PUNCH (Polarimeter to Unify the Corona and Heliosphere) from Vandenberg Space Force Base in California on March 6, 2025.
Relevance of the Topic: Prelims: Key Facts about NASA’s PUNCH Mission; Solar Cycle; Terms related to Sun.
PUNCH Mission
- PUNCH (Polarimeter to Unify the Corona and Heliosphere) is a solar mission that will study the solar corona (the outermost layer of the Sun’s atmosphere).
- Initiative of: National Aeronautics and Space Administration
- Aim: To better understand the solar atmosphere and solar wind.
- Launched using: Falcon-9 rocket from California, the US.
Key Features:
- PUNCH consists of Four identical suitcase-sized satellites in low Earth orbit (LEO) that will continuously image the Sun’s corona (outer atmosphere) and provide origins of solar flares, etc.
- It is the first mission that uses polarisation of light to study the Sun's corona in 3D.
- When particles (such as electrons) scatter sunlight, the waves of light become aligned in a particular direction (this is polarized light).
- PUNCH will measure the light using polarising filters similar to polarising sunglasses, allowing scientists to make a 3D map of features PUNCH sees throughout the corona and inner solar system.
Polarisation of Light
- Light travels in the form of transverse electromagnetic waves. The light emitted by sources like the sun, bulb, candle etc. has vibrations in several planes (oscillates in all directions), and it is called unpolarised light.
- Polarisation is the phenomenon of restricting the vibration of light waves to one specific direction/plane. E.g., Polarised sunglasses have a special filter that allows only light with a specific polarisation direction to pass through, which helps to reduce glare and improve visibility by blocking unwanted polarisations.
Recent Solar Missions
- PUNCH (Polarimeter to Unify the Corona and Heliosphere) is the third major solar mission to be launched in the past 18 months. Since September 2023, two solar missions have been launched. These are:
1. Aditya L1 (India):
- Launched in September 2023.
- Initiative of: Indian Space Research Organisation
- Location: Lagrange point 1 (located at a distance of about 1.5 million km from the Earth).
- India’s first solar mission. It is designed to study solar flares and solar winds, measure low-intensity magnetic fields and solar soft X-ray flux, etc.
Read More: Aditya L1 Mission
2. Proba-3 (European Space Agency):
- Launched in December, 2024.
- Initiative of: European Space Agency
- Launched by: Indian Space Research Organisation.
- Proba-3 aims to study the Sun's corona (the outer layer of the Sun’s atmosphere) and solar winds.
Read More: Proba-3 Mission
What is the Solar Cycle?
- Solar cycle is the cycle that the Sun’s magnetic field goes through approximately every 11 years.
- Every 11 years or so, the Sun's magnetic field completely flips, i.e., the Sun's North and South poles switch places.
- Then, after another 11 years, the Sun’s north and south poles flip back again. This periodic change is known as the solar cycle.
- The solar cycle affects activity on the surface of the Sun, such as sunspots which are caused by the Sun's magnetic fields.
- Solar Minimum: Beginning of a solar cycle when the Sun has the least sunspots. Over time, solar activity and the number of sunspots increases.
- Solar Maximum: Middle of the solar cycle when the Sun has the most sunspots. As the cycle ends, it fades back to the solar minimum and then a new cycle begins.
Why do space agencies want to make the most of Solar Maximum?
- According to the National Oceanic and Atmospheric Administration (NOAA) and NASA, the Sun has entered the solar maximum phase around October 2024, which could continue for another year.
- Solar maximum is the best possible window available for physicists to both launch and observe the sun, as the solar activities peak during this period. Giant eruptions on the Sun, such as solar flares and coronal mass ejections increase during the solar maximum.
- The next possible intense solar activity will be around 2035-2036.
Key Terminology related to Sun
| Terms | Description |
| Solar Magnetic Field | Complex magnetic field that exists due to the constant movement of electrically charged particles within the Sun (in its interior). |
| Solar Wind | Continuous flow of charged particles from the Sun. Created by the outward expansion of plasma from the Sun’s surface (plasma is continually heated to the point that the Sun’s gravity cannot hold it further). It travels along the Sun’s magnetic field lines. |
| Sunspots | Temporary spots (small, dark and cooler areas) on the Sun’s Photosphere, where magnetic fields are particularly strong. Solar flares tend to originate from regions that contain sunspots. The number of sunspots can indicate the likelihood of solar flare eruption. |
| Solar Flares | Sudden and intense burst of solar energy from the Solar atmosphere. It is caused by the release of magnetic energy stored in the Solar atmosphere. The energy is released in the form of light/radiation and high energy charged particles. |
| Coronal Mass Ejection | Large-scale expulsion of plasma and magnetic field from the sun’s outer atmosphere or corona into space. |