The Sun - Our Solar System

  • Age: 4.5 billion years (approx)
  • Distance from Earth: 150 million km
  • Diameter: 1.4 million km
  • Core temperature: 15 million ºC
  • Surface temperature: 6,000 ºC
  • Satellites: Everything else in the Solar System

The Sun is the star at the centre of our Solar System. It is a giant nuclear reactor with a mass of approximately 75 per cent hydrogen and 25 per cent helium.

At the heart of the Sun, the solar system the pressure is high enough for nuclear fusion reactions. Every second millions of tons of hydrogen nuclei fuse together and produce helium nuclei. This process releases energy, providing us with the heat and light that sustains life on solar system Earth.

It is so hot that most of the Sun, space station isn’t gas at all but plasma - the fourth state of matter. Plasma is what you get if you take a gas and heat it up even more. Eventually the atoms will break apart into charged particles, whizzing around at high speeds.

The solar system Planets, space station asteroids and other satellites within the Solar System all orbit the Sun which, like Earth, also has a north and south pole and rotates on its axis.

Space Weather

Every second a million tonnes of hot plasma and charged particles (electrons and ions) escape the Sun’s gravity into space station. This material is known as the solar space wind. Space weather is the effect all these millions of charged particles have on the science discovery Earth and depends on solar system activity. As the solar system wind carries the Sun’s magnetic field with it, when it connects with the Earth’s magnetosphere this also causes space weather.

The most visible sign of space shuttle weather is the aurora – the Northern or Southern Lights. These beautiful patterns in the upper space technology atmosphere are usually seen in the polar regions. An aurora is caused when the charged particles of the solar wind interact with the Earth’s magnetosphere, the magnetic bubble surrounding the Earth. This generates a current between Earth’s upper atmosphere and the magnetosphere.

Just as currents flow through a neon light to light up the gas, so the currents flowing between the magnetosphere and upper atmosphere light up gases in the Earth’s atmosphere to produce aurora.

Every so often the Sun, Star and galaxy belches out billions of tonnes of particles and a magnetic field in events known as coronal mass ejections. If one of these heads towards the Earth it can trigger a disturbance of the Earth's magnetic field called a geomagnetic storm.

Large geomagnetic storms can cause power cuts and knock out communications space station satellites. Coronal mass ejections can drive shock waves of energetic particles that could injure space astronauts working in orbit.

The Solar system Sun also produces solar flares. These tremendous explosions in the atmosphere of the star and galaxy directly affect the Earth’s upper atmosphere disrupting radio communications.


NASA’s twin Solar Terrestrial Relations Observatory (STEREO) is sending back the first 3-D images of the solar system Sun. The two spacecraft mission are also studying the nature of coronal mass ejections. The spacecraft mission carry cameras developed by the University of Birmingham and the STFC Rutherford Appleton Laboratory (RAL).

The Japanese Hinode space mission is studying the processes involved in solar flares and coronal mass ejections. Designed and built by teams in the US, Japan and the UK, the spacecraft mission has key involvement from University College London’s Mullard Space Science Laboratory (MSSL) and RAL.

The Solar and Heliospheric Observatory (SOHO) is a joint project between the European Space Agency (ESA) and NASA and has been studying the Sun from its deep core to outer corona.

ESA’s Cluster Space mission is studying the Earth’s Space Technology environment. It consists of four identical spacecraft mission flying in formation, hundreds to thousands of kilometres apart. Each spacecraft mission carries 11 identical instruments, three of which are led by UK space station scientists. Cluster is being operated in conjunction with China’s Double Star space station mission.

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