Diamonds have been found in the sky based on the spectra of interstellar light and the measured absorption spectra of nanodiamond. For example, the surface of a nanodiamond is often terminated by the absorption of hydrogen. These carbon–hydrogen (C–H) bonds may vibrate to emit or absorb electromagnetic radiation with a characteristic wavelength. Nanodiamond may also form inside a giant star that undergoes an explosion to form a supernova. However, more commonly, nanodiamond particles may be formed when carbon-containing molecules collide with one another in interstellar dusts. Most of these nanodiamond particles contain hydrogen terminated bonds on its surface. In addition to diamonds that may found buried deep in stars, and those that may rain down from the atmosphere on planets, diamonds are also ubiquitous in other places. Since carbon atoms exist everywhere in the universe, the frequent impact of these atoms has the potential to form diamond inevitably.