Everyone knows you should never look directly at the sun. In its brilliant brightness, to do so is to risk serious damage to your eyes. Given such brilliant brightness, it’s tempting to think that our star is a uniform ball of light. In reality, it has a highly complex structure, and it has all sorts of surface features. Most of these are only visible to wavelengths other than those we can see. But one set of features is visible - if you have the right kind of gear to protect your eyesight, of course!
These are sunspots, darker spots on the surface of the sun that are slightly cooler and are places where increased magnetism is happening (this reduces convection of heat from within the sun, and hence the region is cooler than its surroundings). Sunspots consist of two parts: the central umbra, which is the darker part with magnetic field that is approximately vertical, and the outer penumbra, the lighter area where the magnetic field is more inclined.
Towards solar minimum, sunspots become a lot less common. But this week, the space weather community has been getting increasingly excited by sunspot region 2673.
It came onto our radar on Sunday as it began to expand. Originally consisting of one sunspot, it very quickly began to grow and develop to what SpaceWeatherLive described as ‘a little army worth of sunspots’.
By Monday, itvery rapidly increased in magnetic complexity (going from simple Alpha sunspot (a simple-structured sunspot with a single pole) to complex Beta-Gamma-Delta in just 48 hours.
Sunspots can be classified according to their magnetic complexity. Here are some of the classifications relevant to region 2673:
A Beta sunspot group is bipolar (i.e. with a positive and negative polarity);
A Gamma sunspot region is a complex one with irregular distributions of positive and negative poles.
A Beta-Gamma group is a bipolar group, but with such complex magnetic structure that the you can’t draw lines between spots of opposing polarity.
A Beta-Gamma-Delta group is a Beta-Gamma group with a Delta
As Monday went on, 2673 spewed out a series of solar flares (a sudden release of magnetic energy that has built up in the sunspot region - the bigger solar flares are classified as M-class; the biggest flares are X-class). These included quite large M1 flares and an M5.5 flare at 21.33 BST.
These flares launched two CMEs (Coronal Mass Ejection - an eruption of super-heated plasma from the sun’s corona that speeds out into space). The first was a slower one, but the second was faster and wider - and directed pretty much towards the Earth. The two are likely to join together and arrive at the Earth on Wednesday.
It will enhance the solar wind that is affecting the Earth, increasing its speed. If the magnetism of the plasma cloud is favourable (if the Bz is south), then this could produce some impressive aurora displays on Wednesday and Thursday. There are no guarantees (and the weather forecast for Northern Ireland isn’t great for Wednesday night), but there is at least a chance!
Capturing the image
Taking the shot
Given all I was reading about this sunspot region, I was very keen to try to photograph it. I used my 300mm zoom and - very importantly - my Baader solar filter to image this shot on Tuesday evening. Without that filter, there is a strong chance of permanent damage to your camera sensor! I put my camera on the tripod to keep it steady, set the aperture at f8 (to keep the image sharp) and a shutter speed of 1/500 second.
In terms of post production, first I processed the RAW file in Adobe Camera Raw as shown below:
I changed the Temperature to give a more pleasing hue to the sun, boosted the Whites and lifted the Vibrance. In the Sharpening panel, I boosted the Luminance to reduce noise as high as I could before I started to lose structure in the sunspots.
I then imported the image into Photoshop.
I added a Curves layer to give the image a bit of punch and a Burn layer the make the spots themselves pop a bit more. Finally, I knew I wanted a pretty close in crop to these sunspots, so I upscaled the image (Image>Image Size) in two stages of 200%, so that the image would be made bigger without becoming pixelated), then I cropped and saved.
This is without doubt the most complex set of sunspot regions I have imaged. And even if the CMEs don’t result in aurora over the next few days, I was pretty delighted to have been able to capture this image of our most incredible sun.