Local bubble housing our solar system. Computer artwork of the local bubble, a low-density cavity in the interstellar medium, that houses the Sun and other stars. The axes show the size of the local bubble in light years. It contains hot, ionised gas that emits X-rays. It is thought to have been formed by a nearby supernova pushing aside gas and dust, leaving behind hot low-density material. Estimates of when it was formed vary from some hundreds of thousands of years ago to a few million years ago.