The Sun - power house

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Vital Stats

The Sun is the Power House for the entire Solar System. It is a fairly typical star that is not burning, but is fusing together Hydrogen to form Helium. In so doing, it releases energy in vast quantities.

Live image: click to enlarge.
Source: Hawai'i Institute for Astronomy

Middle Aged

The Sun has existed for 5 billion (5,000,000,000, or 5×109) years. It is one of 150 billion stars in our galaxy, The Milky Way. Despite consuming 5 million tonnes of Hydrogen every second, there is enough material left for it to exist for another 5 billion years.

A Typical Star

Stars can exist with between 1/20 and 70× the mass of our Sun, making it somewhat average. Heavier stars have much shorter lifetimes, since their greater gravity increases the rate of fusion. This also makes them hotter and brighter than our Sun, whose surface temperature is about 6000K. More on stars.

Fusion Perfected

On Earth, humans use Nuclear Fission to produce energy for some of our electricity supply. This is somewhat inefficient, and produces very dangerous nuclear waste. The Sun uses the technically more difficult Nuclear Fusion to produce its energy: 3×1026 joules per second! (3×1026 W).

Fusion: PP Chain
Fig. 1: Fusion of Hydrogen into Helium

In studying the Sun, we humans have learned how to produce energy from Nuclear Fusion. This century, it may become our main source of energy.

Revealing Spectrum

Once it was learned that the Sun is just an ordinary star, scientists on earth realised that if we learned about the sun, we were learning about the stars. In the diagram below, the spectrum of the Sun is shown. As you can see, there are lots of unexpected black lines.

Solar Spectrum
Fig. 2: The Solar Spectrum

Spectral Lines

The black lines seen in the solar spectrum are Fraunhofer lines. They indicate the presence of chemical elements in the Sun. Light from other stars is similar - from their spectra we learn about what they're made from. Click for more.

Top Right ^^

closest view yet of a sunspotSunspot Revealed!

This photo was taken in 2002 by the Swedish 1-metre solar telescope on La Palma, and is the most detailed picture ever of the Sun's surface. Sunspots are caused by twists in the Sun's magnetic field. A new page will appear here shortly! Source: Institute for Solar Physics, Stokholm

Spectacular Auroras!

The Sun's influence reaches out far beyond the earth. A "solar wind" of charged particles is continuously bathing all the planets. At earth, this causes the auroras - the so-called northern and southern lights. Read more.

SOHO Success

comets hitting sunThe Sun has been under study for years, but not until late 1995 did major discoveies start to be made with the launch of the the joint NASA/ESA probe, SOHO.
Sun quakeIn April 1998, the British-built and operated CDS spectrometer on board discovered tornadoes wider than Africa! The Sun has even been seen to have regular quakes, as shown on the right. In June 1998, SOHO observed two comets crash into the Sun in quick succession, as shown top right. For the latest information, check the SOHO website.

Death of the Solar System

In 1 billion years, the Sun will be bigger and hotter than it is today. The Earth's oceans will have boiled away into space. Stars start to die when they stop burning hydrogen. The sun, a yellow, G-2 star, will (in 5 billion years) then become a red giant encompassing the orbit of Mercury. Mercury will disappear and Venus will lose its atmosphere and become a burnt out planet. The Earth will suffer the same fate, even though it is outside the red giant's immediate reach.

Life Cycles of Stars

An active tale. Check it out!

GCSE Material

Find out much more about the sun on GCSE.com.


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