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AstroNoir Blog Posts

The Sun: A story of our solar system and space weather

The Sun is a star which, according to Merriam-Webster, is a gaseous spheroidal celestial body, with self-luminosity and energy coming from its many nuclear fusion reactions.

Our Sun is a G-type, main-sequence star. These are also referred to as G stars or yellow dwarfs.

Main Sequence Stars with the Sun displayed as a G star. Image Credit: Universe Today


4.6 billion years ago, within a large molecular cloud, the matter experienced gravitational collapse. A lot of the mass was focused on the center. The outer part flattened into a disc orbiting the larger center.

The dust and particles within the disc collided, becoming larger bodies of mass such as asteroids or planets. The more rockier planets being found closest to the Sun. It is believed that this is due to the solar wind blowing gasses further away, and the Suns gravity attracting the heavier elements.

Let there be light

The Sun has a large abundance of Hydrogen and Helium. These elements are used during nuclear fusion reactions. These nuclear fusion reactions happen when two lighter elements collide to form heavier elements. It is estimated that in the core of the Sun about 600 million tons of helium and hydrogen fuse together every second. During these reactions there are often leftover 'waste' material, as the resultant heavier element does not constitute the entire mass of the previous elements. The leftover mass is therefore released as energy. About 4 million tons of matter is converted into energy per second. This energy can be released in many different ways. Eventually leading to events such as coronal mass ejections, and flares.

Electrically-charged particles of plasma rise through to the surface, known as the photosphere, of the Sun . Solar wind is the outward expansion of plasma, forming the Sun's corona. The heat from the solar wind overpowers the gravity and allows for the plasma to escape along the Sun's magnetic field lines.

Map of the Suns layers. Image Credit: NASA


In summary, the Sun can be seen as a big ball of fire and gas (FYI it's actually made of plasma)!

A rocky start

We lie within the 'Goldilocks' (habitable) zone. Where is it not too hot and not too cold. The conditions are just right for rocky materials to form, as well as allow for hydrogen and oxygen to exist together in liquid form, eventually leading to life.

The solar systems Goldilocks zone. Image Credit: Petigura/UC Berkeley, Howard/UH-Manoa, Marcy/UC Berkeley


Within the Earths atmosphere, the abundance of elements differ from the Sun and are as follows:

  1. 78% Nitrogen

  2. 21% Oxygen

  3. 0.93% Argon

  4. 0.04% Carbon dioxide

  5. Other trace elements such as neon, helium, methane, krypton, ozone, hydrogen, and water vapor

However, Earth is not just a ball of gas. It has layers that can exist in other phases.

Much like the way that the gaseous planets venture far from the centre of the solar system, due to being less attracted to the Suns gravity, the lighter elements are more concentrated in the Earths atmosphere and the heavier elements are found closer to the core. Element abundances, therefore, vary throughout the Earths different layers. The geological history shows that the Earth has been through multiple different conditions with chemistry changing throughout time. Whereby there were times of tumultuous asteroid hits, such as the one suspected to have happened during the formation of our moon, and volcanic eruptions of super volcanoes. In terms of intelligent life, we have occupied this blue planet for just a brief time whilst Earths conditions have been perfect, or might we say suitable, for our existence.

Nevertheless, how can life be sustained with the Sun constantly throwing harmful particles towards us?

Planetary defense: The solar systems magnetic fields

Magnetic fields are fairly common within the solar system. The Earth, the Sun, our terrestrial cousin Mercury, and the gaseous giants Jupiter, Saturn, Uranus and Neptune all exhibit one.

The solar magnetic field is made through complex self-sustaining dynamo systems. Where the Suns plasma supports magnetic fields through it's electrical conductivity. These magnetic fields then have forces that affect the plasma, with the fluids motion maintaining continuous systems.

The Suns magnetic field has two poles, which flip every 11 years when the Sun is at it's peak of activity.