Solar Insights: Understanding Our Sun and Its Effects

Introduction to Sun

The sun is the central star of our solar system, around which earth along with other planets revolves. It is primarily composed of hot gasses.

• Age of the sun: Approximately 4.6 billion years
• Diameter: 1.39 million kilometers
• Temperature of the sun: Around 6000°C on the surface and a scorching 16 million°C in the core
• Density: 1.41 times that of water (Water’s density = 999.97 kg/m³; Earth’s overall density is 5.5 times that of water).

• Surface Gravity: 274 m/s², which is 28 times that of Earth
• Rotation Speed: Approximately 7179.73 km/hour, significantly faster than Earth’s rotational velocity of 1675 km/hour
• Period of Rotation: Completes one rotation in about 25 days and 9 hours
• Rotation Direction: Counter-clockwise when viewed from a perspective far above Earth’s north pole
• Mass of the sun: Equivalent to approximately 332,900 Earth masses
• Composition: Composed mainly of hydrogen and helium, accounting for about 98% of its mass
• Solar System Mass Dominance: Although the Sun makes up about 99.8% of the solar system’s total mass, it contributes only about 2% of the angular momentum due to its gaseous, differentially rotating structure.

Layers of Sun:

Layers	Components	Description
Inner Layers	Core	Innermost layer with a temperature of 15 million℃. It serves as its energy powerhouse, responsible for generating all of its radiant energy. The core’s extraordinary temperature and density, driven by immense pressure, create the ideal conditions for nuclear reactions to occur. Within this crucible, nuclear reactions continually yield heavier elements, contributing to the diversity of elements on the periodic table.
	Radiative zone	Energy transfer from the Sun’s core, where it originates, to the outer regions occurs through a process known as radiation. This mechanism carries energy from the Sun’s central core to the surrounding regions, giving rise to the term “radiative zone.”
	Convection zone	It is a layer within the Sun (and other stars) where energy is transported via convection (Process in which hot, less dense material rises, while cooler, denser material sinks). It lies just above the Sun’s radiative zone and extends outward from below the surface to a depth of about 200,000 kilometers. In this zone energy is carried primarily by the movement of hot plasma (ionized gas). Hot material rises from the lower layers of the Sun to the surface, transporting heat and energy with it.
Outer Cells	Photosphere	One of the most important layers of the sun. All the visible light comes from this zone. It is the coolest part of the Sun, having a temperature of around 5500℃. Photons produced in this layer escape the sun through the transparent solar atmosphere above it as solar radiation. Phenomena such as Sunspots occur in the photosphere.
	Chromosphere	Red-coloured layer above the photosphere. The temperature gradually increases with altitude. Light is visible from this region only during the solar eclipse when the photosphere is hidden.
	Corona	The outermost layer of the Sun. It is seen as a bright white spot during the solar eclipse. This layer is responsible for coronal or solar mass ejection

Solar winds: The Solar Breeze that Shapes Space Weather

• Definition: They are a continuous stream of charged particles, primarily electrons and protons, that are ejected from the outermost layer of the Sun’s atmosphere, known as the solar corona, into space.
• Composition: It consists mainly of charged particles, primarily electrons and protons, with trace amounts of heavier ions and atomic nuclei.
• Origins: They are generated by the Sun’s extreme heat and magnetic activity.
  • They are primarily expelled from regions on the Sun with open magnetic field lines, such as coronal holes and active regions like sunspots.
• Impact on Space Weather: They play a significant role in space weather.
  • When they interact with the Earth’s magnetosphere, they can cause geomagnetic storms and disrupt satellite communications, power grids, and navigation systems.

Exploring Solar/Stellar Flares: The Sun’s Electromagnetic Fury

• About: It is a dramatic increase in the brightness of a star due to magnetic energy stored in the star’s atmosphere.
• Formation: It is often accompanied by coronal mass ejection.
• Composition: They eject clouds of electrons, charged ions and atoms with electromagnetic radiation.

• Impact of Solar/Sun’s Flare: From Polar Lights to Sterilization
• • Polar Lights: when the sun flare hits the earth’s upper atmosphere, it excites the molecules of nitrogen and oxygen in the atmosphere.
    • These excited molecules produce polar lights or aurora.
  • Aurora Borealis: The interaction of sun flare and earth’s magnetic field at the North pole produces Aurora Borealis, also known as Northern lights.
  • Aurora Australis: The interaction of solar flare and earth’s magnetic field at the South pole produces Aurora Australis, also known as Southern light.
  • Disruption in Communication: X-rays and UV rays may affect and disrupt long-range radio communications.
  • Hurdle in man space mission: Radiations due to solar flare pose one of the major hurdles for man space mission.
  • Sterilization: Huge amounts of energy can strip water from the atmosphere and sterilize the ground.

Coronal Mass Ejections (CMEs): Sun’s Impact on Technology

• CMEs are large-scale eruptions of charged particles (plasma) and magnetic fields from the Sun atmosphere into space.
• They have the potential to disrupt various ground- and space-based technologies, including satellites, on Earth.
• CMEs exhibit a wide range of plasma temperatures, from cold chromospheric material (around 104 K) to hot plasma (around 107 K).
• As CMEs propagate through space, various processes can exchange energy, including electrical, kinetic, potential, and thermal, which can either heat or cool the plasma within them.
• Significance: For assessing their impact on Earth’s communication systems.

Sunspots: Dark Regions and Solar/Sun Cycles

• About: They are created due to magnetic fields created over the surface because of which the region becomes darker and cooler than surroundings.
  • They are regions on the Sun’s surface, known as the photosphere, that appear darker than their surroundings.
  • They are not present all over the Sun’s surface, present between 25° – 30° latitude.

• Solar Cycle and Sunspots: In every solar cycle, the number of sunspots on the Sun’s surface goes through a periodic increase and decrease.
  • The current solar cycle, which commenced in 2008, is presently in its ‘solar minimum’ phase.
  • During this phase, the number of sunspots and solar flares on the Sun is at a relatively low and routine level.
• Characteristics:
  • The number of sunspots fluctuates every 11 years due to the Sun’s magnetic activity. Thus it is known as the Sunspot cycle.
  • Some sunspots can be as large as 50,000 kilometres in diameter.
  • Despite appearing dark, the temperature within a sunspot remains extremely hot, at around 6,500 degrees Fahrenheit (3,600 degrees Celsius).
  • The photosphere is the visible surface of the Sun and emits most of the Sun’s light directly toward Earth.
  • Some Sunspots appear cooler because they form in areas where the Sun’s magnetic fields are exceptionally strong.
  • The magnetic fields within sunspot areas can be approximately 2,500 times stronger than Earth’s magnetic field.
• Two Regions of Sunspots:
  • Umbra: the darker central part known as the ‘umbra’.
  • Penumbra: the lighter surrounding region called the ‘penumbra.’

Attempt the Previous Year Question (Prelims)

Q. If a major solar storm (solar flares) reaches the Earth, which of the following are the possible effects on the Earth? (2022)

1. GPS and navigation systems could fail.
2. Tsunamis could occur in the equatorial region.
3. Power grid could be damaged.
4. Intense auroras could occur over much of the Earth.
5. Forest fires could take place over much of the planet.
6. Orbits of the satellite could be disturbed.
7. Shortwave radio communication of the aircraft flying over the polar region could be interrupted.

Select the correct answer using the code given below:

1. 1, 2, 4, and 5 only
2. 2, 3, 5, 6, and 7 only
3. 1, 3, 4, 6, and 7 only
4. 1, 2, 3, 4, 5, 6, and 7

Answer: C

Q. The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs (2012)

(a) the water vapour of the air and retains its heat
(b) the ultraviolet part of the solar radiation
(c) all the solar radiations
(d) the infrared part of the solar radiation

Ans: (d)