A view of the sun in white light revealing the sun’s visible surface, called the photosphere. Of course, looking at the sun is dangerous and it’s important to use the right tools and certified equipment. Never leave an unfiltered scope pointing at the sun, you can see the damage this caused to an end cap after only a couple of seconds in one of the photos below, imagine if that was your eye. White light viewing and imaging means filtering out most of the harmful light reaching your eye and camera sensor and there are several ways to do this. I’m using the universally popular Baader AstroSolar Safety Film across full aperture on an 8″ reflector. This specialist material blocks out 99.999% of the sunlight and results in an image of the sun’s natural colour of neutral white revealing the visible surface, the photosphere.
With good seeing you may be able to see the mottled surface of the sun, solar granulation, the effect of limb darkening, faculae and plage near sunspot active regions and if the sun is active, sunspots with the dark centres known as umbra and the lighter region around it know as penumbra. Sunspots are areas of intense magnetic activity, often in pairs and having the opposite magnetic pole to each other. They appear black because they are cooler than the surrounding surface, caused by the hindering of conductivity from the intense magnetic activity making a cooler area. They are still very hot and if you could isolate these, would be brighter than a full moon.
I’ve managed to capture a few frames in the mid morning before the clouds have rolled in, while the sun is high enough up in the sky and before the sun has a chance to warm up the atmosphere with heat thermals and effect the seeing (wibbly wobbly atmosphere). This effect is worse in the winter when the sun is low down in the sky and you are trying to view through a thicker portion of the atmosphere. Easier to image at this time of the year when the sun is high in the sky, although the Earth is at its farthest point in its orbit around the sun (aphelion was on 4th July 2014 at a distance of 94.5 million miles compared to its average of 93 million miles ). Remember it is the tilt of the Earth that causes the seasons not the distance from the sun.
For these images taken a week apart, I have used a Canon 1000D DSLR using a Canon EOS T ring on a Skywatcher 8″ telescope and stacked around 40 pictures at 1/2000 sec exposures in Registax to form a single image. I’ve then adjusted and artificially colored in Photoshop but not used any flatframes to remove dust bunnies from the sensor. It appears that I have some discolouration on my Baader solar film that looks like rust and could be defective. Then again it’s cheap enough to be disposable and there really shouldn’t be a price on the safety of your eyes.
What you can see from the two images, one taken on the 2nd of July and the other on the 10th of July, is the progression of the sunspots as they rotate across the face of the sun and how they can change in shape. At this rate, I’ll be in danger of getting the specialist solar telescope out, the Coronado PST, although cloud free sunny days have severely impacted on its use this year, think I’ve only had one image from it this year. Webcam astronomy, any astronomy in fact, has been very lacking this year. Makes it hard to justify any purchases.