The Sun’s internal structure is composed of several layers, each with distinct characteristics and roles in the Sun’s behavior and energy production. These layers, from the innermost to the outermost, are:

1. Core: – Location: Center of the Sun, extending outward to about 20-25% of the Sun’s radius. – Temperature: Around 15 million degrees Celsius (27 million degrees Fahrenheit). – Role: The core is where nuclear fusion occurs. Hydrogen nuclei (protons) fuse to form helium, releasing vast amounts of energy in the form of gamma rays.

2. Radiative Zone: – Location: Extends from the edge of the core to about 70% of the Sun’s radius. – Temperature: Ranges from about 7 million degrees Celsius at the inner boundary to about 2 million degrees Celsius at the outer boundary. – Role: In this zone, energy produced in the core is transferred outward by the process of radiative diffusion. Photons are absorbed and re-emitted by the plasma, taking millions of years to pass through this layer.

3. Convective Zone: – Location: Extends from the radiative zone to the Sun’s visible surface (the photosphere), occupying the outer 30% of the Sun’s radius. – Temperature: Drops from around 2 million degrees Celsius at the bottom to about 5,500 degrees Celsius at the top. – Role: Energy is transported by convection. Hot plasma rises towards the surface, cools, and then sinks back down to be reheated and rise again, creating convective currents.

4. Photosphere: – Location: The Sun’s visible surface, about 500 kilometers thick. – Temperature: Approximately 5,500 degrees Celsius (9,932 degrees Fahrenheit). – Role: This layer emits the sunlight that we see. It’s where the Sun’s radiation is released into space. Sunspots, cooler regions caused by magnetic activity, are visible in this layer.

5. Chromosphere: – Location: Above the photosphere, about 2,000 kilometers thick. – Temperature: Ranges from about 4,000 degrees Celsius at the bottom to around 25,000 degrees Celsius at the top. – Role: This layer is observed as a reddish glow during solar eclipses. It’s where the temperature rises rapidly with height, contributing to the heating of the corona.

6. Corona: – Location: The outermost layer, extending millions of kilometers into space. – Temperature: Extremely hot, ranging from 1 million to 3 million degrees Celsius. – Role: The corona is the Sun’s outer atmosphere and is visible during total solar eclipses as a white halo. It is the source of the solar wind, a stream of charged particles that flow out into the solar system.

Understanding the Sun’s structure helps astronomers comprehend solar phenomena like sunspots, solar flares, and the solar wind, and their effects on the solar system, including Earth’s space weather.