The Sun, while shining, gives off radiation across the electromagnetic spectrum, but the Earth's atmosphere stops most of it.
Some radiation does reach the Earth's surface, such as visible light, infrared and ultra-violet.
Infrared is a radiation that you can feel from the Sun as heat. Ultraviolet is stopped by glass, which is why you do not tan in a glasshouse, but infrared is a problem as it can go through glass easily. Well, that is due to the infrared rays being concentrated at the focus. This ability to heat items up is something we must be careful of if we are going to observe the Sun, and it must be in our minds constantly. So with this in mind, let's see what telescope can be used for solar observing.