Tracking Sunspots Across the Sun
A sunspot is a cooler area on the surface of the sun, which shows up as a patch that is darker than the rest of the sun’s surface. A sunspot generally lasts for about two weeks. Sunspots usually happen in groups. Sunspot activity happens in cycles that peak about every eleven years, and relates to cycles of magnetic activity in the sun.
Sunspot reports might go back as far as 28 BC. In 1612, Galileo Galilei, a physicist, mathematician, astronomer, and philosopher, tracked sunspots across the sun and calculated that the sun revolves once every 27 days.
Make a Pinhole CameraLooking directly at the sun can cause eye damage. Instead, look at the sun using a pinhole camera. Ibn al-Haytham invented the first pinhole camera in the 10th Century.
Make a pinhole in a piece of stiff paper, or cut a five centimetre square in the paper, tape a piece of kitchen foil over the square and make a hole in the foil (this will make a smaller and neater hole). Go outside on a sunny day and hold the piece of paper with the pinhole up above another piece of paper. This will make an image of the sun on the second piece of paper. Moving the top piece of paper will change the size, brightness and focus of the image of the sun – try about a metre apart.
Making a number of holes (or using something like a kitchen colander) will make a number of images of the sun.