4. The Sun

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4. The Sun is a typical star; emitting electromagnetic radiation and particles that influence the Earth

4.1 - Identify that energy may be released from the nuclei of atoms​​​​​​s

Most nuclei are stable, consisting of protons and neutrons that are unaffected by chemical reactions, which have remained the same since their formation

However some nuclei are not stable and spontaneously release energy in the form or alpha particles, beta particles, or gamma rays

These nuclei are known as radioactive

Substances that are radioactive can undergo transmutation - the changing of one element into another by means of nuclear decay

This release of energy from the nucleus has been used for nuclear medicine, power and weapons

4.2 - Describe the nature of emissions from the nuclei of atoms as radiation of alpha α and beta β particles and gamma γ rays in terms of: ionising power, penetrating power, effect of magnetic field, effect of electric field

Alpha Particles

These consist of two protons and two neutrons, the same as a helium nucleus

When a nuclei emits an alpha particle, its mass decreases as well as its atomic number, so it undergoes transmutation

Alpha particles are also good ionisers - they cause electrons to be knocked out of its orbit in an atom due to their mass and size

They will travel for only a few centimetres before becoming a helium atom - a harmless inert gas

Since they possess a charge of two protons, a force is exerted in them when they move through an electric or magnetic field, causing them to accelerate and deflect from their original path

These types of particles are used in smoke detectors

Beta Particles

These are high speed electrons that come from the nucleus, often originating from neutron-rich nuclei

When a neutron spontaneously decays into a protons and an electron, the electron (beta particle) is immediately ejected from the nucleus at high speed, while the nucleus contains an extra proton and transmutates

Beta particles are much smaller and will ionise as well as alpha particles, but can penetrate matter further

They also have the charge of an electron and will experience a force when they move through electric or magnetic fields - at the same speed, a beta particle will experience half the force that an alpha particle does, however since it has a much lighter mass, this force will cause much greater deflection than alpha particles

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Gamma Rays

These are very high frequency, short wavelength electromagnetic radiation, which are emitted from the nucleus

They are associated with fission and fusion of nuclei and can accompany alpha or beta decays

They have a very high ability to penetrate matter while having a low ability to cause ionisation

Gamma rays are not particles and do not possess any electric change - as a result, they are unaffected by electric and magnetic fields

Gamma rays are used to treat cancerous tumours and in specialised industrial applcations

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4.3 - Identify the nature of emissions reaching the Earth from the Sun

The most obvious emissions from the sun that reach the earth are light and heat

Other less forms of electromagnetic radiation are also emitted by the sun and reach the earth

The photosphere (surface of the sun) radiates with a temperature of 5800K and emits EM radiation of all wavelengths - this radiation peaks at the visible region of the spectrum

Solar wind is also another continuous stream of particles that reaches the earth

4.4 - Describe the particulate nature of the solar wind

Solar wind is a stream of particles ejected from the sun which consists mostly of protons travelling at about 400km/s, as well as electrons and ions which make up a small percentage - its density is measured in protons per square centimetre

This originates from the corona - an extremely hot region surrounding the Sun that extends as far as several million kilometres above the photosphere

This region causes the particles to move so fast that gravity can no longer keep them around the Sun

Solar wind travels through space and is deflected by the Earth's magnetosphere

4.5 - Outline the cyclic nature of sunspot activity and its impact on Earth through solar winds

4.6 - Describe sunspots as representing regions of strong magnetic activity and lower temperature

The sun's photsphere has a surface temperature of about 5,500 degrees C, and is not a real surface, but is in violent motion, subject to strong convection currents welling up from beneath

The motion of the charged particles produces intense, dynamic magnetic fields

When these fields warp and twist around each other, magnetic storms can disrupt the motion of the convection currents near the surface and form sunspots - spots or patches that appear from time to time on the sun's surface, appearing dark by contrast to its surroundings due to being cooler by several hundred degrees

The number of sunspots present goes through a cycle of peaking and declining that is, on average, 11 years long

In peak periods of sunspot activity, the total energy of the sun increases slightly and solar wind is at its most intense

Solar flares (brief eruptions of high-energy radiation from the sun's surface) and coronal mass ejections (unusually large explosions of magnetic field and plasma from the Sun's corona) are more likely to occur at this time as the sun's surface becomes more turbulent

This can lead to the disruption the earth's magnetic field to disrupt power supplies and satellite communications

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4.2P - Identify data sources, gather and process information and use available evidence to assess the effects of sunspot activity on the Earth’s power grid and satellite communications

When charged particles of solar wind enter the region influenced by the earth's magnetic field, they are deflected towards the polar regions, changing the magnetic field of the Earth's surface

This can induce voltages in long transmission wires, resulting in overloads that trigger safeguards that cut out power supplies to entire regions

Satellite communications may also be affected as the charged particles induce voltages in satellite electronics which can overload the components

The interaction of solar wind particles with the ionosphere can also produce radio wave energy that may swamp the signals being sent by satellites

As a result of these consequences, soar flare activity is closely monitored by a number of satellites