Sen—This week we saw the return of the largest sunspot group on the Sun for about 25 years. Called active region 12172, we first saw it in mid-October when it caused a huge amount of interest because it’s vast size meant it harboured the energy to power intense solar flares and large and fast coronal mass ejections (CMEs) which can drive stormy space weather at Earth. In one respect it didn’t fail to perform and produced a whole series of intense flares. But on the other hand it didn’t produce the coronal mass ejections we were expecting and so was less ‘active’ than we predicted. Now, enough time has passed for the Sun to rotate, bringing this sunspot group back into our view. And this has happened just in time for a European gathering of scientists, policy makers, engineers and forecasters interested in understanding and predicting space weather. So, in between the scheduled talks, conversations were being had as to why the sunspot region didn’t produce the eruptions, and therefore the stormy space weather, that we were worried about.
I went along to the meeting, called the 11th European Space Weather Week, in Liège in Belgium. There was an impressive turnout of about 350 people from Europe and abroad, which demonstrates that we see space weather as a global issue to tackle. NASA and NOAA where there, as were the UK Met Office (I have recently written about their space weather forecasting centre) and many scientists from around the world. There were a couple of things that caught my eye…
From NASA, we had an update on the work being carried out with the Curiosity Rover on Mars. But this time it wasn’t related to looking for signs of extinct or extant life. The rover carries an instrument that can detect very high energy electrically charged particles that originate either at the Sun (during flares or coronal mass ejections) or from the galaxy. One of the tasks of the Curiosity rover is to characterise the particle radiation level; both while it was en route to the red planet and also during its exploration on the surface. NASA has long-term plans to send astronauts to Mars and the measurements that Curiosity is taking is helping understand the hazard that these particles might pose when humans venture outside the Earth’s protective magnetic field and atmosphere for many months at a time. So far, the level of particle radiation has been lower than expected which is encouraging. But the particles still pose a major hazard and astronauts will still need to be shielded from their damaging effects.
The focus of the week though was very much on Europe and the European Space Agency (ESA) had a lot to report. ESA is growing a network of services to provide information about the Sun’s activity and the weather conditions in space. After all, ESA’s space instrumentation could be at risk (the team operating the Rosetta spacecraft receive space weather reports) and one of the main ways to monitor the weather conditions is to use spacecraft. No matter how you look at it, ESA is a natural focus for space weather in Europe. So a series of Expert Service Centres is being established that collectively monitor solar activity, the conditions in the region between the Sun and the Earth, the level of particle radiation, the state of the Earth’s magnetic field and the state of the Earth’s upper atmosphere (known as the ionosphere). These centres then make their findings freely available.
There was a strong turnout from the UK too, which included a presentation of an idea of how to safeguard ourselves by building a dedicated space weather satellite. This builds on the UK’s long and successful track record of research that has helped us understand the physical processes that create space weather, as well as the space instruments we build and collaborations with industry. The idea proposed is for a satellite is called ‘Carrington’. Airbus Defence and Space has led the overall design but my university, UCL, and also Imperial College London and RAL Space would provide instruments on the satellite. Carrington is just a concept at the moment but the idea is to send the satellite to a point in the Solar System where it can look out toward the Sun and the Earth. The telescopes onboard will then be able to carefully watch the Sun and identify any eruptions that the Sun sends our way. At the very heart of Carrington though are the needs of those who use space weather, for example the Met Office.
My work in space weather is based around the eruptions (which are called coronal mass ejections) and why and how sunspot groups produce them. I had come to think of these eruptions as a natural part of the lifetime of a sunspot group and something that they probably all produced. So it was a huge surprise to me that region 12172 was so inactive in terms of eruptions. Now that I am back from the meeting, it is time to try and answer the questions that this sunspot region has raised so that we can progress our scientific understanding of space weather.