Which constellation is known for having the brightest star Deneb?

Deneb is indeed the brightest star in the constellation Cygnus. This constellation, often referred to as the Swan, is prominent in the summer sky of the northern hemisphere. Deneb is not only known for its brightness but also as part of the Summer Triangle asterism, which includes two other bright stars from the constellations Lyra and Aquila.

Its name, Deneb, comes from the Arabic word for "tail," reflecting its position as the tail of the swan in the sky. Deneb is also significant as it is a supergiant star, and, despite being a considerable distance from Earth, is one of the most luminous stars visible to the naked eye.

Other constellations such as Hercules, Libra, and Gemini do not feature Deneb as their brightest star. Hercules is known for its multiple bright stars and the Great Hercules Cluster, Libra is represented by the Scales in mythology, and Gemini is recognized for its twin stars Castor and Pollux. Thus, the correct choice highlights the distinct identity of Cygnus within the celestial landscape, as it houses Deneb, making it significant both astronomically and culturally.