Distance travelled ~ 603'268'000 km
(Lucie Green is a solar researcher based at the Mullard Space Science Laboratory, UCL's Department of Space and Climate Physics. She studies activity in the atmosphere of our nearest star, the Sun, with particular focus at immense magnetic fields in the Sun's atmosphere. Lucie is also a Science writer and has been involved in a variety of Science programmes such as Sky at night and recently Radio 4's programme the infinite Monkey cage.)
It seems that barely a week goes by at the moment without the Sun being in the news, for seemingly contradictory reasons. One minute we are being told that the Sun is going to cause a global disaster as the result of super-sized solar activity, the next that Sun is going into hibernation. So, what exactly is going on?
Courtesy of SOHO/EIT consortium. SOHO is a project of international cooperation between ESA and NASA
The Sun has a cycle in which its magnetic field pulses in size and complexity roughly every 11 years. Coronal mass ejections (CMEs), huge bubbles of magnetic field containing charged particles, are a natural part of this cycle. At the moment we are approaching solar maximum (expected to occur around 2013) which means that the number of ejections is on the rise and so too are some worrying consequences here on Earth.
CMEs can inject charged particles into the Earth's magnetic field which, if accelerated, lead to the beautiful aurora. The flipside is that these particles can also damage our satellites, lead to satellite failure and produce currents in our power lines causing problems for national power grids. Most notably, in 1989 a transformer in the Canadian national grid failed due to such currents and several million people lost their electricity for over nine hours. So, the increasing number of CMEs is good news for people wishing to view the aurora but bad news for our space-based and electrical infrastructure.
Some news articles are predicting that in 2013 the perfect solar eruption will occur that will cause a global disaster through the simultaneous failure of electricity networks all over the world and the loss of the satellites that modern society relies on for communication, navigation and banking. However, many aspects need to come together to produce this 'perfect solar storm' which makes such an event hard to forecast. This scenario isn't pure fiction though.
The reasoning is based on studying previous events, in particular a solar eruption that occurred in 1859 which produced such a strong display of the aurora that they were seen down toward the equator. If this event repeated itself today it is likely that the worldwide damage caused would cost a trillion dollars. [For more information on how coronal mass ejections affect us: NOAA/Space weather prediction center ]
No individual solar cycle is the same as the next though, and this brings me to another reason that the Sun has been in the news. The Sun has only recently come out of the deepest solar minimum for 100 years. Things have been very quiet on the Sun. So whilst some are worried that the Sun might cause global destruction, others are worried that the Sun is going to switch off. On the face of it these are contradictory stories but on closer inspection this is not so.
On the timescale of a few years solar activity and the number of CMEs is on the rise and we will experience more effects on our technology. However, on the timescale of decades, it looks like the magnetic cycle of our Sun may decline. This idea could be extrapolated to conclude that the Sun will switch off altogether but in reality there is an very small chance of this happening. Things may quieten down, but they will pick up again.
Ultimately, we are living in a gusty outflow of magnetic field and charged particles coming from the Sun. This has led to a new era of 'space weather' prediction where we are monitoring the near-Earth space environment to make sure we protect ourselves from the harmful effects of the Sun's emissions. Whatever level of activity the Sun decides to produce we will feel the consequences. Understanding and predicting the weather in space should be given a high priority.