The National Air and Space Museum holds some of the most hallowed objects of the aerial age. Visitors can marvel at the 1903 Wright Flyer that skimmed over Kitty Hawk, N.C., the bright red Lockheed 5B Vega that Amelia Earhart piloted alone across the Atlantic Ocean and the bell-shaped Friendship 7 capsule that made John H. Glenn Jr. the first American to orbit the Earth. Now, the museum said, it will display a spacecraft that has flown only onscreen, in an entirely fictional galaxy where good and evil seem locked in eternal battle. That’s right: An X-wing Starfighter will grace the museum’s newly renovated building on the National Mall sometime late next year, the museum said on Tuesday, which was celebrated by “Star Wars” fans as a holiday because it was May 4 (May the 4th be with you).