An Ikea Bowl Has Been Setting Things on Fire
The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their windowsills).Every once in a while a house fire is started because the sun sat at just the right angle at a certain time of the year, placing the focal point on the curtains. But because the risk is so low (it doesn't happen that frequently) many people are completely unaware of the phenomenon.