That's one of the nice things about the clickable links and other resources on the 'Net. If you don't know a term or phrase, just research it or ask me or ask a regular poster to this thread. We're glad to help!
For instance: "Nebula": Latin for "mist"; in astronomy it refers to an area of dust and/or gas. They glow by ionizing radiation (like a fluorescent light) from associated stars, or by reflected starlight, or appear dark.