Have you ever noticed that peeling sticky tape produces sparks of light? Maybe not, unless you like to wrap gifts in the dark. This phenomenon is known as triboluminescence and was first described by Francis Bacon in 1605 after he found that scratching sugar cubes caused them to give off light.

Triboluminescence is the release of energy in the form of light that occurs when two contacting surfaces move relative to each other. Although the precise mechanisms behind this phenomenon are not fully understood, it has been suggested that it is caused by the separation of opposite charges; when these are then neutralized a burst of energy is released which can be seen by the naked eye.

Intriguingly, UCLA researchers found that unwinding sticky tape can actually emit X-rays. But don’t worry, this occurs only when carried out in a vacuum- your Christmas present wrapping days are safe.

When the researchers tried this out, they found that peeling sticky tape actually released enough X-rays to take an image of one of the scientists’ fingers using a dental X-ray detector. Check out a video of the scientists in action released by Nature here: