I believe only the Gryffindor House has a password, but maybe not. In book 7 when Harry was going with Luna into the Ravenclaw House it was not a password, but a question. If you answer it correctly you will enter if not you won't.
Helena Ravenclaw is played by Kelly Macdonald.
No. Cho was a Ravenclaw.
The duration of Madre Luna is -2700.0 seconds.
YESS! luna 1 is still in orbit.
Luna Lovegood is a Ravenclaw.
"Wit beyond measure is a man's greatest treasure" -- Rowena Ravenclaw Ravenclaw's are smart in one way or another - For example, Cho was academically bright whereas Luna was insightful and philosophical.
Luna is a Ravenclaw. Luna was a Ravenclaw student who is one year younger than Harry.Ravenclaw.
"What comes first fire or phoenix?"
Yes, Cho Chang did try and take Harry to the Ravenclaw common room to look for the Lost Diadem in Harry Potter and the Deathly Hallows however Ginny was unhappy about this and suggested that Luna Lovegood took him.
'Wit beyond measure'. At least, according to the bust of Rowena Ravenclaw in Deathly Hallows, when Luna takes Harry to look for a Horcrux.
Rowena Ravenclaw, Founder of the Ravenclaw House, Mother of Helena Ravenclaw, the Grey Lady.
Helena Ravenclaw, AKA the Grey Lady, Ghost of the Ravenclaw Tower.
She is introduced in the 5th book, 'Harry Potter and the Order of the Phoenix'. Her first appearance is on the Hogwarts Express, when Harry, Neville and Ginny sit the same compartment as her. She's portrayed as being a highly unusual witch, with controversial ideas and beliefs about bizarre creatures. Her father, Xenophilius, runs an alternative wizard magazine that supports Harry when the mainstream newspaper, The Daily Prophet, doesn't. In the films, she is portrayed by Evanna Lynch. Luna Lovegood is a Ravenclaw from Ginny Weasley's year. She is described as having waist-legnth dirty-blonde hair and prominent bright silvery-blue eyes. She also has very pale skin and is thin. She doesn't care what others say about her and is friendly towards those around her although not many of the characters are willing to give her a chance at being their friend except for Harry, Hermione, Ron, Ginny, and Neville. All of them from Gryfindor. Luna is also known as "Loony" Lovegood behind her back. Evanna Lynch plays Luna
Ravenclaw house colours are blue and bronze. In the movie, they are blue and grey.
The mascot of Ravenclaw House is an eagle, as shown in the image above. The House is named Ravenclaw not because its mascot is a raven, but because its founder is Rowena Ravenclaw. However, in the film adaptations, the mascot of Ravenclaw is an eagle.
Professor Flitwick is the Head of Ravenclaw.