Activity on the Sun continues to rise, as the maximum of the 11-year solar cycle approaches. Large sunspots are now a regular sight, and displays of the northern lights are likely to become increasingly common.
Solar activity, as shown by the number of sunspots, rises and falls in a regular cycle. Back in December 2019 there were hardly any sunspots on the Sun’s surface, but now the Sun is peppered with them – and activity is expected to rise. Sunspots are cooler regions that appear dark by contrast to the hotter solar surface. They are driven by the Sun’s magnetic field and can be seen in groups, or on their own, as so-called active regions.
Astronomers have been monitoring changes in sunspot numbers ever since 1755, when regular observations began. The current cycle of activity is the 25th, and the question that solar observers are asking is ‘When will maximum occur?’
It is difficult for experts to predict the date of solar maximum and how high it will be, in terms of the number of sunspots seen. This unpredictability, however, can make the Sun fascinating to observe.
It looks like solar maximum will occur in 2024 or 2025, but activity has already exceeded that of the peak of the previous sunspot cycle, solar cycle 24. We only know when the peak has occurred with hindsight, by observing that activity is declining.
See sunspots for yourself
Because the Sun is so bright is can easily blind you if you don’t take proper precautions. The safest way to observe sunspots is to use a suitable solar filter on the front of a telescope. As well as sunspots you may see faculae – bright patches that appear towards the edge of the solar disc. These bright patches typically occur near sunspots.
Using a more specialist hydrogen-alpha solar filter, or complete solar telescope, means that you can observe in a very narrow red part of the visible spectrum and see sunspots, filaments, prominences, plage and occasionally flares in the lower atmosphere, or chromosphere, of the Sun. These phenomena and how to observe them safely are explained on the Solar Section’s webpages.
Seeing the northern lights
The increase in solar activity means that it is also worthwhile keeping an eye out at night for displays of aurorae, or northern lights, that often follow powerful solar flares and coronal mass ejections. Solar flares are explosions in the lower atmosphere of the Sun, while coronal mass ejections occur when heated gas is ejected from the Sun.
Already, as solar activity rises aurorae have been seen as far south as Cornwall or even France, and the likelihood of displays being seen across the UK will increase during solar maximum. One of the best websites for receiving updates on solar activity and giving warnings when auroral activity may occur is spaceweather.com. At this website, you can subscribe for free email updates.
Keeping track of sunspots
If you don’t have the appropriate equipment, or time, to observe the Sun, or you just want to know what SPA members have seen, you can look at the SPA’s Solar Section’s News webpage, where the latest solar images and drawings that have been submitted by SPA members are posted by the Section’s Director. If you start making regular observations, then you may want to consider submitting them to the Solar Section. To join the SPA just click the ‘Join’ button at top right!
Neil Waby