Big news: The Air and Space Museum has embarked on an enormous, multi-year, $1-billion makeover, which will most certainly affect your experience if you visit in 2019. The entire west wing—half of the museum—will be closed, as will several exhibits in the east wing. These exhibits mostly focus on aviation history and exploration. At some point in 2019, the main museum shop will close, and so will the Einstein Planetarium (probably summer of 2019). Should you still come? Well, of course! There’s still lots to see.
Based on visitation numbers (7 million annually, prior to the renovation), this is America’s favorite museum. And even in its current state, it’s not hard to understand why. The National Air and Space Museum manages to tap into that most primordial of human impulses: the urge to fly. And it does so in a multi-layered fashion, mixing extraordinary artifacts with IMAX movies, videos, and hands-on exploration of displayed equipment.
The seeds of this museum were planted when the Smithsonian Institution acquired its first aeronautical objects in 1876: 20 kites from the Chinese Imperial Commission. By the time the National Air and Space Museum opened on the National Mall 100 years later, the collection had grown to tens of thousands of objects. Today, the inventory of historic aircraft and spacecraft artifacts numbers more than 66,000, the world’s largest such collection.
The place is huge, as is much of its collection. Enormous aircraft and spacecraft dangle from the ceiling or are placed in floor exhibits throughout both levels. Visitors of all ages, but mostly families, take pictures of each other against the backdrops of the towering Pershing II (34.8 ft.) and SS20 Pioneer (54.1 ft.) missiles, or the Hubble Space Telescope (42 ft.), or just about anything in the museum, as most of the artifacts dwarf humans. Tours and demonstrations are in constant rotation.
And, unfortunately, there are often lines—many, many lines. The first is just to enter the building, and you can expect longer waits when the museum closes its Independence Avenue entrance sometime in 2019. Then there are lines to get tickets for IMAX films ★, or a show at the Einstein Planetarium ★.
On view in 2019 are the east wing’s exhibits, which focus mainly on space exploration and history. First-floor galleries cover the Space Race and the development of huge telescopes (Explore the Universe); the space-themed galleries upstairs highlight Exploring the Moon, and Time and Navigation in space. 
The central area on both floors takes a look at historic milestones and individuals in aviation and space research and development: Space and aviation artifacts in the first-floor Boeing Milestones of Flight Hall illustrate ways that aviation and flight transformed the world. This is where you'll see the first American jet aircraft, the Spirit of St. Louis [SS], flown solo by Charles Lindbergh across the Atlantic Ocean. 
If you’re short on time or simply overwhelmed, there are two things you shouldn’t miss. The Sky Lab Orbital Workshop ★★★, in the Space Race gallery on the first floor (you enter the spaceship on the second floor), allows you to walk through the country’s first space station. You’re actually inside the astronauts’ living quarters; if you look up, you’ll see that most of the rocket’s construction lies overhead. And be sure to visit the second-floor Wright Brothers exhibit, where the Wright brothers’ 1903 Flyer ★★★, the world’s first successful airplane, is on display.
Amateur astronomers should head outside to the museum’s east terrace to peer through the telescopes in the Phoebe Waterman Haas Public Observatory. The observatory is free and open to the public Wednesday to Sunday noon to 3pm for daytime sightings of moon craters and sun spots, and once or twice a month for nighttime observations (more info on the website).
Or get off your feet for a while and take in an IMAX film, like the ever-popular To Fly, or Planet Power 3-D, or watch a show at the Albert Einstein Planetarium ★. The planetarium offers a free show daily at 10:30am, but you must obtain a ticket from the box office. Otherwise, tickets for IMAX and planetarium films cost anywhere from $7.50 to $15 per person (plus $3 per ticket processing fees), depending on the film, age of filmgoer, and whether the person is a Smithsonian Institution member. 
Wonder where the museum has put all of the aircraft and equipment that used to occupy the west wing? Much of it now resides temporarily in the National Air and Space Museum’s companion location, the Steven F. Udvar-Hazy Center, adjacent to Washington Dulles International Airport. If you’re hungry to see more aviation artifacts and spacecraft, or if you’ve got a flight leaving from Dulles Airport and have time to kill, drive the 25 miles out to the satellite museum. Here you can explore one huge hangar filled with aviation objects, another with space objects, each arranged by subject (Commercial Aviation, Korea and Vietnam Aviation, Sport Aviation, and so on). Perhaps the center’s most notable artifact is the space shuttle Discovery. The observation tower gives a bird’s-eye view of planes landing and departing at Dulles Airport. IMAX movies and simulator rides also are options.