The conversational equivalent of photobombing. Usually unintentional, the perpetrator is just a fuckwit. An unwanted guest who takes over the conversation and cannot be persuaded to leave directly or otherwise.

The safeguarding of Earth and other worlds from biological cross-contamination (i.e. billionaires with too much time on their hands).

Also known as “planetary protection.” Planetary protection / quarantine “reflects both the unknown nature of the space environment and the desire of the scientific community to preserve the pristine nature of celestial bodies until they can be studied in detail.”

There are two types of interplanetary contamination. Forward contamination is the transfer of viable organisms from Earth to another celestial body. Back contamination is the transfer of extraterrestrial organisms, if such exist, back to the Earth's biosphere.

A person who enters a conversation without being asked there opinion. Usually they think they have something important to say but in actuality are a extremely annoying.