The Sun: A Detailed Overview

Basic Characteristics

The Sun is a star, significantly closer than other visible stars.
Many believe the Sun is an average star, but it's actually in the top 10% by size and number.
The Sun is the dominant object in our solar system: it's 1.4 million kilometers across and 300,000 times more massive than Earth.

Composed mostly of hydrogen gas.
In the Sun's core:
- Pressure: 260 billion times Earth's atmospheric pressure.
- Temperature: 15 million degrees Celsius.
- Hydrogen is completely ionized, creating a soup of subatomic particles.
- Protons fuse to form helium, releasing energy per Einstein’s E=mc^2.

Every second, 700 million tons of hydrogen convert into 695 million tons of helium.
The missing mass converts to energy, equivalent to detonating 400 billion one-megaton nuclear bombs per second.
It takes 100,000 to 200,000 years for energy to travel from the core to the surface.

Convection Zone: Hot gas rises, cools, then sinks, transferring heat efficiently.
Photosphere: Thinner, cooler layer where density drops, and light escapes into space.
Corona: Extremely thin, hot outer layer visible during eclipses, extending millions of kilometers.
Solar Wind: Stream of particles moving away from the Sun, primarily along the equator at about 1 million km/h.

The Sun's surface and plasma dynamics are influenced by complex magnetic fields.
Sunspots: Darker, cooler areas where tangled magnetic fields inhibit convection.
Faculae: Bright edges of sunspots, enhancing overall solar brightness.
Prominences/Filaments: Large arcs of plasma following magnetic loops.
Solar Flares: Explosive releases of magnetic energy, capable of releasing 10% of the Sun’s total energy output.
Coronal Mass Ejections (CMEs): Massive ejections of solar material, similar to hurricanes.

Solar flares and CMEs can disrupt Earth's magnetic field, leading to auroras and potentially damaging power grids and satellites.
Notable historical solar storms:
- 1859 Carrington Event: Most powerful recorded solar storm.
- 1989 Quebec blackout caused by a solar storm.
- 2012 event narrowly missed Earth.

Critical for predicting and mitigating the effects of solar activity on modern society.
Essential for understanding the very basis of life and its dependence on solar energy.