General Studies Paper 3

Context

• Observations from Adtiya L1 will help us understand the dynamics of the Sun and how solar variability impacts the climate on Earth and affects the space weather.

Monitoring the Sun

• Discovered by mathematician Joseph Louis Lagrange, L1 is one of the five points located approximately 1.5 million kilometres away, where the gravitational forces of the Sun and the Earth are in equilibrium.
• Hence, a spacecraft placed at L1 orbits the Sun at the same rate as Earth and affords an uninterrupted view of the Sun, making it an ideal observation post for space-based solar observatories.
• The L1 is currently home to the European Space Agency (ESA)- National Aeronautics and Space Administration (NASA) Solar and Heliospheric Observatory (SOHO) observing the Sun and its dynamics.
• Aditya L1 will join this observatory to unravel the mysteries of the dynamics of the Sun.
• Launched on September 2, the craft will undergo five orbit-raising manoeuvres before being slingshot to the L1 point.
• The ship will coast for about four months before it reaches L1. At that stage, the thrusters will be fired to make the craft circle around the L1, placing it in what is known as a halo orbit around L1.
• From this vantage point, Aditya L1 can observe the Sun 24X7 using its four remote sensing payloads, and measure in-situ the various parameters of space weather.

To understand climate variability

• Like a heartbeat, solar activity is measured in terms of the number of sunspots.
• Sunspots are cooler regions on the Sun’s surface which increase and decrease in a cycle of 11 years.
• When the Sun is active, the number of sunspots is in the hundreds, and at solar minimum, the numbers are nearly zero.
• Whatever changes we observe in the solar radiation, nearly 80% occur in the ultraviolet range.
• The Earth’s upper atmosphere absorbs most of the solar UV rays. The absorbed energy affects the atmosphere’s composition, temperature and other parameters.
• The Solar Ultraviolet Imaging Telescope (SUIT) developed by the Inter-University Centre for Astronomy & Astrophysics, will observe the UV radiation from different zones of the solar atmosphere.
• The onboard intelligence system will detect any sudden appearance of bright spots, such as solar flares on the disc.
• Observing the Sun using the SUIT will enable us to better understand climate variation on Earth.

Looking deeper

• At times, the Sun sneezes. Like a tongue of fire, a chunk of the corona suddenly accelerates and leaps into interplanetary space.
• Called Coronal Mass ejection (CME), this cloud consisting of billion tonnes of energetic plasma mixed with a solar magnetic field is hurled at 250 kilometres per second to 3,000 km/s.
• Usually, the corona is not visible in the glare of the radiant Sun, except during the brief moment of a total solar eclipse.
• However, solar physicists can create artificial eclipses in the solar telescope, called coronograph, to observe the corona.
• The Visible Emission Line Coronagraph (VELC) developed by the Bengaluru-based Indian Institute of Astrophysics in close collaboration with the ISRO can peek as close as 1.05 solar radii, a region never imaged by any solar telescope.

Conclusion

• Earth’s climate has definitely changed. Global warming is real. The data from SUIT and other papers of Aditya L1 will help us resolve the contribution of natural and anthropogenic factors driving climate change.