Aurorae - Polar Lights
Created | Updated Jan 28, 2002
Beautiful, fascinating, magnificent but also damaging
Aurorae are the result of the interaction between our magnetic field, our atmosphere ad the solar wind. The solar wind is made up of many charged particles, elements and isotopes that are present in the sun, these are ejected in events that are called Coronal Mass Ejection’s. These are eruptions from the inside the sun appear as sunspots. As this ‘wind’ reaches the Earth it is deflected by our magnetosphere an invisible shield created by the Earth’s magnetic field which protects us from such particles. However at the North and South pole (which South and North geographic poles respectively) the field lines go towards Earth, like a funnel. There is a very good picture of themagnetospherehere, sorry I cant reproduce it.
The particles follow the field lines down toward Earth where they begin to ionise the molecules in the air, mainly Nitrogen and Oxygen. When these are effected they give off the light of the aurora, the colours directly relate to the element which is excited (I think this is the same process as the production of line spectra where as the electrons drop energy levels in the atom they give off photons of light)
Aurorae are only mainly visible near to the Earth’s poles where the funnels exist and so only very northern and southern latitudes witness them, aurora in the North are called aurora borealis and in the south aurora australis. It is certainly worth having a trip to Alaska for example to witness the true spectacle. However the aurorae depend on the Sun and the sun is not at all constant as it has an 11 year cycle of activity. In peak times there are vast numbers of sunspots produced and therefore more solar storm head towards us. This not only means that the aurorae are more frequent but more violent, which is good news for anyone wanting to see the aurorae because they are often visible in mid latitudes so that if you live around 50+ degrees N or S your may witness these events from your own home. This occurred on Thursday 6th of April where people in Britain were witness to a beautiful display of aurora borealis. 2000 is the peak of the 11 year solar cycle so this year should be great for aurorae.
The same solar wind can reek havoc with some Earth and space systems such as power production, there is the famous case in America (date?) where large amounts of the power grid was disrupted and massive blackouts resulted. Satellites have been put out of service, so they are now occasionally aligned to escape from the worst of the storm. Radio reception is also effected, but to the advantage of some. Aurora effect the Earth’s ionosphere1, where the particles are ionised, this acts to reflect radio waves which can allow radio amateurs to send their signals further than is normally possible. We are not perfectly safe from the solar wind.
Well NASA run a science e-mail service which does occasionally announce these events in advance along with other space related information, it is free.
Up to date aurora prediction are given, select your country and it will be orientated for your location.
There is also the Space Environment Centre that can provide up to date forecasts, these folk are researching this stuff. Space Weather has real-time pictures and graphs of the auroral activity.
[link removed by moderator]
links can be found here
If I also find out about any in advance I may have time to post the info below, so keep an eye on this space.The large sunspot group ir close to te center of the solar disc, possible eruptions could cause auroral activity.
Aurorae are the result of the interaction between our magnetic field, our atmosphere ad the solar wind. The solar wind is made up of many charged particles, elements and isotopes that are present in the sun, these are ejected in events that are called Coronal Mass Ejection’s. These are eruptions from the inside the sun appear as sunspots. As this ‘wind’ reaches the Earth it is deflected by our magnetosphere an invisible shield created by the Earth’s magnetic field which protects us from such particles. However at the North and South pole (which South and North geographic poles respectively) the field lines go towards Earth, like a funnel. There is a very good picture of themagnetospherehere, sorry I cant reproduce it.
The particles follow the field lines down toward Earth where they begin to ionise the molecules in the air, mainly Nitrogen and Oxygen. When these are effected they give off the light of the aurora, the colours directly relate to the element which is excited (I think this is the same process as the production of line spectra where as the electrons drop energy levels in the atom they give off photons of light)
Aurorae are only mainly visible near to the Earth’s poles where the funnels exist and so only very northern and southern latitudes witness them, aurora in the North are called aurora borealis and in the south aurora australis. It is certainly worth having a trip to Alaska for example to witness the true spectacle. However the aurorae depend on the Sun and the sun is not at all constant as it has an 11 year cycle of activity. In peak times there are vast numbers of sunspots produced and therefore more solar storm head towards us. This not only means that the aurorae are more frequent but more violent, which is good news for anyone wanting to see the aurorae because they are often visible in mid latitudes so that if you live around 50+ degrees N or S your may witness these events from your own home. This occurred on Thursday 6th of April where people in Britain were witness to a beautiful display of aurora borealis. 2000 is the peak of the 11 year solar cycle so this year should be great for aurorae.
The same solar wind can reek havoc with some Earth and space systems such as power production, there is the famous case in America (date?) where large amounts of the power grid was disrupted and massive blackouts resulted. Satellites have been put out of service, so they are now occasionally aligned to escape from the worst of the storm. Radio reception is also effected, but to the advantage of some. Aurora effect the Earth’s ionosphere1, where the particles are ionised, this acts to reflect radio waves which can allow radio amateurs to send their signals further than is normally possible. We are not perfectly safe from the solar wind.
So how do I find out when aurora are likely to occur?
Well NASA run a science e-mail service which does occasionally announce these events in advance along with other space related information, it is free.
Up to date aurora prediction are given, select your country and it will be orientated for your location.
There is also the Space Environment Centre that can provide up to date forecasts, these folk are researching this stuff. Space Weather has real-time pictures and graphs of the auroral activity.
[link removed by moderator]
links can be found here
If I also find out about any in advance I may have time to post the info below, so keep an eye on this space.
Aurora Update
The large sunspot group ir close to te center of the solar disc, possible eruptions could cause auroral activity.
Follow the link for pictures of the aurorae of 6th April
1I'll check
