How Was the Sun Formed?


The sun is the center of our solar system, and it is a huge nuclear reactor: inside, the fusion of hydrogen and helium generates energy at temperatures of around 15 million degrees. Temperatures of around 5700 degrees Celsius still prevail on its surface. From this surface, the photosphere, light and heat are radiated into space.

The sun – the center of our solar system

Our solar system, was formed approximately 4.6 billion years ago. It emerged from a gigantic cloud of gases and dust swirling around. The gases consisted mainly of hydrogen and some helium, the dust from ice particles and some heavy elements such as iron.

The Big Bang – a massive explosion

Now you are probably wondering where the cloud and these elements came from. The answer to this is provided by the Big Bang. About 15 billion years ago, the elements of the Big Bang emerged from nowhere. A massive explosion created space, time and matter.

The entire mass must have been united in an infinitely small and dense point of infinite heat at that moment. This highly concentrated matter suddenly exploded under enormous pressure and expanded. This is how our universe came into being. Hard to imagine, but true.

Primordial gas clouds: origin of our solar system

The elements (hydrogen, helium, iron, etc.) whirled around in an ancient galaxy for several billion years until they finally united to form a huge cloud of dust. This gigantic cloud collapsed about 4.5 billion years ago due to its own gravity.

As a result, the cloud started rotating faster and faster. Due to the fast rotation, the cloud flattened and enormous forces were released, which heated up the flat cloud.

The space in the cloud was getting narrower and the temperature was increasing. Pressure and temperature rose so much in the center of the cloud that dust particles collided more and more frequently. The temperature inside the cloud was already around 10 million degrees Celsius.

In this enormous heat, the hydrogen atom nuclei move so quickly that they melt and become helium nuclei when they collide with each other. This process is called the nuclear reaction, which means nothing other than fusion.

Nuclear reactions also existed in the cloud of gases and dust 4.5 billion years ago and ultimately led to the formation of our sun and our solar system.

The sun: the oldest and largest star in our solar system

Our sun is a self-illuminating sphere made of hot gases, which, unlike Earth, has no solid mass. With a diameter of 1.4 million kilometers, our gigantic fireball is not only the largest celestial body, but also the heaviest.

Compared to the sun, our earth appears tiny with a diameter of 13,000 kilometers. Imagine that the sun is a soccer ball and the earth is a three millimeter ball that is about 30 meters from soccer ball. The Sun to Earth ratio is roughly the same. But although the sun is 330,000 times heavier than our earth, it is not sluggish.

In 25 days the sun turns around itself and at the same time races through the Milky Way at a hell of a pace. At around 220 kilometers per second, the sun moves around the center of the galaxy, our solar system . Inside, human beings can hardly imagine temperatures of 15 million degrees Celsius and the pressure is 200 billion times higher than on Earth. The Sun has six regions:

  1. Core
  2. Radiative zone
  3. Convective zone in the interior
  4. Photosphere (the visible surface)
  5. Chromosphere
  6. Corona (outermost region)

The sun’s core – a fusion reactor

If we take a closer look at the sun, we’ll see that the structure of the sun is similar to that of an onion: it consists of several layers and peels. The core of the sun has a gigantic diameter of about 175,000 km and is a fusion reactor.

Nuclear fusion takes place here at a temperature of 15 million degrees Celsius and ten times the density of lead. A heavy helium nucleus is created from four hydrogen atom nuclei. With this fusion, mass is lost, which is converted into energy.

In just one second, the sun converts approximately five million tons of matter into energy, which it emits into space in the form of heat and light. The most important properties of the sun come from this loss of mass: light and heat.

The radiative zone

The radiative zone is located around the sun’s core. Here the energy is transported from the inside of the sun to the outside in the form of light. However, this layer is so dense and impenetrable that light and heat take a million years to reach the outside, even at the speed of light. When the sun’s rays reach our earth, they are already ancient.

The convection zone

If we move further away from the core of the sun, the temperature drops to “only” three million degrees Celsius and we reach the next layer – the convection zone. The following happens there: Due to the “low” temperature, the energy can no longer be carried to the surface as radiation.

Instead, glowing chunks of matter, so-called granules, rise to the sun’s surface. Here they cool down and sink back into deeper layers. This process is called convection.

Brightest layer: the photosphere

The subsequent layer is called the photosphere. It is the visible surface of the sun and relatively cool at around 6,000 degrees Celsius. This zone consists of a 400 km thick layer of gas that is not solid but impenetrable.

In the photosphere, the energy from the inside is given off as visible radiation, which is why it is also called the brightest layer.

The sun’s atmosphere – two hot gas shells

The chromosphere and the corona together form the solar atmosphere. The chromosphere joins the photosphere as the next layer and is also called the color sphere. It got this name because of its reddish bright color. Here the temperature rises again to around 10,000 degrees Celsius.

The chromosphere is up to 10,000 kilometers high and consists of individual gas jets. The outermost layer of the solar atmosphere is formed by the corona. This zone consists of very thin gas. You can only see the corona during a total solar eclipse.

Then it appears as a white, shining light ring around the darkened sun. The temperature in this layer rises again to several million degrees Celsius.

The sun: facts and figures

  • Mass: 1,989,000,000,000,000,000,000,000,000,000 kg (330,000 times the mass of the earth).
  • Diameter: 1,392,000 km (the earth would fit 109 times around the sun).
  • Age: 4,500,000,000 years.
  • Estimated life: 10,000,000,000 years.
  • Core temperature: 15,000,000 ° C.
  • Temperature in the photosphere: 5,500 ° C.
  • Energy radiance: 383,000,000,000,000,000,000,000,000 watts.
  • Distance to Earth: An average of 149,600,000 km (the distance is different because the Earth’s orbit around the Sun is oval).
  • Components: 75% hydrogen; 24% helium; 1% carbon, oxygen, small amounts of 63 other elements.

Related articles:

What are Stars? A short Introduction.

How old is the moon and how did it form?

Why is the sunset red?

How does a solar eclipse occur?

Does the moon look the same everywhere?



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