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dark matter

(Encyclopedia)dark matter, material that is believed to make up nearly 27% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or ra...

Cologne

(Encyclopedia)Cologne kəlōnˈ [key], Ger. Köln, city (2021 est. metro area pop. 1,129,000), North Rhine�...

exobiology

(Encyclopedia)exobiology or astrobiology, search for extraterrestrial life within the solar system and throughout the universe. Philosophical speculation that there might be other worlds similar to ours dates back ...

Hamburg, city, Germany

(Encyclopedia)Hamburg hämˈbo͝orkh [key], officially Freie und Hansestadt Hamburg (Free and Hanseatic Cit...

espionage

(Encyclopedia)espionage ĕsˈpēənäzhˌ [key], the act of obtaining information clandestinely. The term applies particularly to the act of collecting military, industrial, and political data about one nation for ...

galaxy

(Encyclopedia)CE5 Hubble classification of galaxies: Elliptical galaxies (E) are classified according to the degree of flattening of the ellipse. Spiral galaxies (S) and barred spiral galaxies (SB) are classifie...

electricity

(Encyclopedia)CE5 Electrical and radio symbols electricity, class of phenomena arising from the existence of charge. The basic unit of charge is that on the proton or electron—the proton's charge is designate...

drone

(Encyclopedia)drone or remotely piloted vehicle, a pilotless craft guided by remote control. Aircraft, ships, and land vehicles can be designed or outfitted as drones. Underwater vessels—both piloted and pilotles...

credit card

(Encyclopedia)credit card, device used to obtain consumer credit at the time of purchasing an article or service. Credit cards may be issued by a business, such as a department store or an oil company, to make it e...

modem

(Encyclopedia)modem [modulator/demodulator], an external device or internal electronic circuitry used to transmit and receive digital data over a communications line normally used for analog signals. A modem attach...