Hello ladies and gents this is the Viking telling you that today we are talking about
The Sun
The centre of the solar system around which all the planets, moons, comets and asteroids orbit, the Sun's heat and light are essential for life.
Explore facts about the biggest and hottest object in the solar system.
The Sun facts
- Equator circumference: 4,379,000km
- Radius: 695,700km
- Temperature: 5,973°C to 15,000,000°C
- Average orbital speed around the Milky Way: 720,000km/h (200km/s)
- Star type: Yellow dwarf
- Average time taken to rotate on axis: 27 Earth days
- Number of planets: 8
How big is the Sun?
The Sun is the biggest object in our solar system, with a distance of 695,508 kilometres from centre to surface. It contains 99.86% of the mass of the entire solar system and could contain roughly 1.3 million Earths.
The Sun is an average-sized star. Some stars are just a tenth of its size, while others are more than 700 times bigger. Due to its huge mass and strong gravity, the Sun is a near perfect sphere.
How hot is the Sun?
The core is the hottest part of the Sun, at 15 million degrees Celsius. This is hot enough to sustain thermonuclear fusion, when hydrogen atoms are fused together to form larger helium atoms. This releases an extraordinary amount of energy which in turn is released as heat and light.
The energy produced at the core takes up to a million years to reach the outer layer known as the convective zone. At this point the temperature drops to around two million degrees Celsius. By the time it gets to the surface the temperature is down to a much cooler 5,973°C - but it's still hot enough to boil diamonds.
In the Sun's atmosphere, known as the corona, the temperature begins to rise again to roughly two million degrees Celsius. As distance from the core of the Sun grows wider, the temperature would be expected to drop. This dramatic increase in temperature in the atmosphere is one of the star's biggest mysteries.
The Sun in different colours seen at differnt ultraviolet wavelengths
The Sun at different ultraviolet wavelengths, (l-r) the bright spots are 60 000–80 000ºC, 1 million, 1.5 million and 2 million degrees © SOHO/ESA/NASA
What is the Sun made of?
The Sun is a ball of gas and plasma - around 91% of it is hydrogen gas. Under intense heat and gravitational force this is fused into helium during nuclear fusion.
When the plasma is heated to the temperatures seen on the Sun, it contains so much energy that the charged particles can escape the star's gravity and blow out into space. This is called solar wind - under certain conditions, when it hits Earth's atmosphere it can cause auroras, such as the Northern Lights.
In addition to hydrogen and helium, scientists have detected at least 65 other elements in the Sun. The most abundant of these include oxygen, carbon, nitrogen, silicon, magnesium, neon, iron, and sulphur.
Does the Sun rotate?
Yes. Even though the Sun is not solid like Earth, it still has a rotation as the plasma swirls around its surface. On average, it takes 27 Earth days for the Sun to rotate once on its axis, but different parts move at different speeds. The equatorial regions take just 24 days to rotate and the polar regions more than 30.
What are sunspots?
Sunspots are cooler parts of the Sun's surface, and occur in the photosphere. The temporary splodges across the surface appear darker to us than the warmer plasma surrounding it.
These cooler spots can be up to 50,000 kilometres across. They are thought to be caused by interactions with particularly strong regions of the underlying magnetic field, which slightly reduce the radiation coming up from the core, cooling the surface.
And as always have a chilled day from the Viking
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