Ask Ethan: Where does cosmic dust come from?

"If you want to see the Universe, you have to do more than merely open your eyes. Even with the advantage of large, powerful telescopes, even from far above the limitations of Earth's atmosphere in space, there are still enormous portions of the Universe that are virtually invisible to our optical telescopes. The reason why? Because enormous portions of the Universe are blocked by cosmic dust: small, cold grains of atom-based matter that absorbs and blocks the visible wavelengths of light that human eyes have adapted to see. They obscure enormous regions of the galactic plane, and hinder our ability to observe star-forming regions, planet-forming disks, and objects that lie behind and beyond the plane of the Milky Way."

"Sure, we've developed many techniques, like multi-wavelength astronomy (particularly at longer wavelengths), to help peer through that cosmic dust, and to identify the objects that lie both inside and behind it, but the existence of cosmic dust itself has been a longstanding puzzle for astronomers. This week's Ask Ethan question comes from High School teacher Allan Clark, who was puzzled by its presence, asking: "[when] teaching grade[s] 9 and 10, I taught the following: all matter is made from atoms (grade 9), [and that] stars were formed as gas and dust coalesced, eventually producing heavier elements. As evidenced by my home, dust is a solid, i.e. matter; so my question is what does dust consist of and where does it come from?""

Cosmic dust comprises tiny, cold solid grains made of atoms and molecules such as silicates, carbonaceous compounds, ices, and metal-rich particles. Dust absorbs and scatters visible light, obscuring large portions of the galactic plane and hiding star- and planet-forming regions. Dust forms in stellar outflows and explosions (for example in evolved stellar winds and supernova ejecta) and grows further in the interstellar medium through accretion and coagulation. Dust can be destroyed by shocks and sputtering. Observations at longer wavelengths (infrared, submillimeter, and radio) reveal dust emission and allow study of obscured structures and the processes of star and planet formation.

Read at Big Think