The ancient Chinese thought they were stars inside a solar orb.
The Aztecs thought their Sun god had pockmarks on his face.
A Renaissance astronomer thought they were undiscovered planets.
Some believe they are the cause of climate change or the reason for loss of signal or a “static” on a radio signal.
Even some believe they are linked to waves of paranormal activity and UFO sightings.
We’re talking about Sunspots!
Sunspots are areas that occasionally manifest on the Sun looking like dark spots, they appear on either side of the Sun’s equator in pairs and sometimes in groups called belts. However, sunspots can vary in size some as small as 200 miles (across to some much bigger than the Earth. Individual Sunspots can last for less than an hour to six months for some of the larger ones. Back in 2004 a Sunspot measured 20 times the size of the Earth and could even be seen with the naked eye. However staring directly at the Sun is not recommended and can be harmful to eyes so I will mention later on the safe ways to observe the Sun.
Sunspots appear as dark patches on the Sun because they are cooler than the surrounding photosphere, the outer layer on the Sun. However sunspots are still very hot at around 50000C compared to the rest of the Sun which is about 60000C. Sunspots are carried around the Sun by its rotation and from this movement Galileo was able to track the Sun’s rotational period to around 30 days. However the Sun’s body is not solid and therefore does not have a well defined rotational period, modern scientists have realised the rotational period is different across the Sun as at the equator the period is 25 days compared to about 36 days near the poles.
There have been periods through history when the Sun has had little to no activity on its surface, most recently as the start of this year (January 2014). The solar calm was a confusing period for scientists as according to their calculations the Sun should have been rife with activity. Richard Harrison, head of the space physics department at the Rutherford Appleton Laboratory in Oxfordshire explained that ‘I’ve been a solar physicist for 30 years, and I’ve never seen anything quite like this.” The only reasonable conclusion was that the Sun had reached its solar maximum; a point in the 11 year cycle when the activity of the Sun peaks.
Dr Lucie Green of the University College London agreed with Richard Harrison at the time saying, “It’s completely taken me and many other solar scientists by surprise.” Previously through history this has happened before, however it was over 200 years ago in the 17th Century.
This known period of solar respite is referred to as the Maunder Minimum and any records from the time mention the Sun being completely clear of any sunspots. An analysis of ice-cores, which can hold a long term record of the Sun’s activity show that the decline is the fastest that has been seen in over 10’000 years. Professor Mike Lockwood of the University of Reading believed that with the rapid decrease in the Sun’s activity, within the next 40 years there was a chance the Earth could be back in the same Maunder Minimum conditions.
When this happened before in the 17th Century, Europe experienced bitterly cold winters and even earned the name ‘The Little Ice Age.’ Given this, the UK felt the effects of a solar calm with the Thames in London freezing. This area was then used for frost fairs as annual snow cover increased too and even areas of the Baltic Sea froze over. With these regional weather disturbances would it be too much to assume the lack of solar activity has a direct affect? Well Professor Lockwood believes that these conditions are linked and the lack of solar activity in January has increased the Earth’s chances of heading back to the Maunder Minimum from 10% to nearly 30%.
However with the Earth’s climate being affected by global warming, mostly contributed to by humans can we really assume mass weather fluctuations are solely the fault of the Sun. Despite many believing the Sun’s activity can override that of greenhouse emissions, the Intergovernmental Panel on Climate Change sits firmly with the understanding that solar variation only contributes slightly to the Earth’s climate.
With this in mind sunspots do affect the Earth in other ways and in fact they affect the ionosphere which is the very upper layer of the Earth’s atmosphere. When there is a high amount of activity, a large amount of matter from the Sun is released in the form of a ‘solar wind’ or coronal mass ejections also known as solar flares. Charged particles in the wind bounce off and interact with the Earth’s atmosphere and can even affect satellites through background static. With heightened solar activity there is a period of increased heat which again affects the Earth’s atmosphere. In this case the atmosphere swells which endangers any satellites in orbit as the rate of decay increases dramatically too (readers with long memories will recall this was reason for the early demise the American Skylab space station). As satellites are interfered with, damaged or destroyed, this then affects many of the items we use on a daily basis such as mobile phones, internet and television not to mention global communication, transport and other electrical equipment worldwide.
As the particles hits the atmosphere we also experience periods of outstanding beauty in the form of Aurorae or better known as the Aurora Borealis or the Northern Lights as we know them in the Northern hemisphere. The lights were named by Galileo Galilei who believed they were caused by sunlight reflected by the atmosphere. For a 17th century astronomer he wasn’t entirely wrong as the Aurora Borealis are caused by solar particles released during solar flares. The particles hit a magnetic field that surrounds the Earth guiding the stream of particles towards the poles, causing us to witness glowing lights in the sky above as the solar particles slam into gas atoms in the upper atmosphere.
Aurorae appear in different colours such as red, green, purple and blue which is the effect of these particles colliding with different gases within the Earth’s atmosphere. The Aurora Borealis are predominantly visible surrounding the North Pole and the further north an observer can travel, the higher the chance of experiencing the Aurora. However they have been spotted during the months of September and October, March and April in the United Kingdom and earlier this month (September 2014) aurorae were spotted over Northern Ireland.
Aurorae are not prevalent just in the Northern hemisphere as there are aurorae in the Southern hemisphere surrounding the South Pole, however they are known as the Aurora Australis or commonly as the Southern lights. The Aurora Australis are slightly more difficult to experience as the Antarctic is arguably the best location for viewing, although they have been experienced on the island of Tasmania, southern parts of Australia and Southern parts of New Zealand.
The Sun is a fascinating solar object and life would be arguably non-existent without the Sun.
Despite this major factor technology has only allowed research into the Sun to extend over the past few years as observing the Sun has proven to be difficult. Looking directly at the Sun is dangerous and should be avoided. Any individual should avoid looking at the Sun directly through a telescope, binoculars or any other observing objects as the outcome can be as serious as loss of sight. However if observing the Sun is of interest there are many safe procedures ranging from the use of paper to modifying a telescope for safe use. These different methods can be found at http://www.skyandtelescope.com/astronomy-news/observing-news/how-to-look-at-the-Sun/.
Although in these modern times we understand the Sunspot cycle, their part in producing solar flares and equally aurorae. We understand the dangers to satellites and the Earth’s atmosphere; however as it stands the astronomy community and physicists cannot fully admit to understanding the total effects of Sunspots and coronal mass ejections. Scientists were surprised by the decrease in solar activity at the beginning of the year as they have been left confused so many times before. So it is possible that the Sun still harbours many secrets as our mysterious neighbouring star, and intense research is needed into the Sun’s apparent design of sunspots.
(Article by Samantha Steed, Education Support Officer)