The Big Dipper is:

A. A retired civil servant with two pensions.

B. A pothole on Whitehurst Freeway.

C. A three-scoop ice-cream cone.

D. A constellation visible in the Northern Hemisphere.

If you answered "D," you may be one of a growing number of Washingtonians with their eyes on the skies. Fostered by three-planetariums, an observatory, a space museum and a cornucopia of programs and classes, stargazers and sophisticated astronomers alike have plenty of opportunity to practice the ancient science.

"Put a little sky into your landscape," advised Robert McCarcken of the National Capital Astronomers (NCA). "It's a healthy thing to do -- gives you a sense of perspective."

To put stars in your eyes, try:

For the Rank Amateur -- Because the night sky evolves, swirls and often fills with clouds, the best way to get a handle on it might be to try out a copy. Planetariums "package" the sky in its ideal condition, helping you to make your way through hundreds of constellations and millions of stars visible to the naked eye.

The Nature Center at Rock Creek Park (Military and Glover Raods NW) steers stargazers as young as 4, with a planetarium program at 1:15 p.m. every Saturday and Sunday. At 4 p.m. they run a program geared to a more sophisticated level; minimum age is 7. Both shows are free, but tickets -- available a half-hour beforehand -- are required.

The Einstein Spacearium at the National Air and Space Museum (7th and Independence Ave. SW.) daily runs a special noon show called "Noontime With the Stars," to introduce stargazing to the public.

Classes -- Steve Smith, Arlington Country's Planetarium director, gives a six-week course for "Mom, Dad and as many kids as they can shove into the back of the station wagon, all for one price." Your $8 ( $10 for non-residents) will provide the whole family with planetarium guidance, outdoor viewing, and enough preparation to make astronomy a part of your family's activities. Classes have already started, but you might see if you can still sneak in by calling Smith at 558-2868.

Smithsonian Associates also plan to run astronomy courses again this year. Call 381-5157.

The Real Thing -- By now you should be ready to scrutinize a non-imitation sky. Guidance is available from the National Capital Astronomers; call McCracken at 229-8321 for dates of their public stargazing programs.

For an in-depth look at the sky, try the 26-inch refractor telescope at the Naval Observatory (34th and Massachusetts Ave. NW). Evening tours include a gaze at celestial objects through the 106-year-old viewer, which made history in 1877 when it was used to discover the moons of Mars. You must sign up for the popular night tours in advance by writing the observatory.

The Universe in Paperback -- Even people who think a map of the stars is a guide through Hollywood can browse through the astronomy shelf of the Smithsonian's Air and Space Museum shop. Here you'll find a couple of basic guides: the "Golden Guide to Stars" ($1.95) and a new method for recognizing star patterns by H.A. Rey (familiar to parents as the author of CURIOUS George"), called "Find the Constellations" ($3.95).

Those smitten with the folklore of astronomy should enjoy R.H. Allen's "Star Names" ($5.50). And for $5.95, you can purchase a handy tool called "Whitney's Star Finder" -- a plastic locator wheel with a 100-page description of its use.

The field of astronomy has grown, well, astronomically since the start of the space age, and those raised with a friendly sky full of bears, dogs and Roman gods will appreciate some help deciphering black holes, pulsars, quasars and their odd kin.

For a comprehensive -- and enjoyable -- tour of the new astronomy, check your library for Kenneth Weaver's article, "The Incredible Universe," from the May 1974 National Geographic. The Geographic's shop (17th and M Streets NW) also sells a $4 plastic Map of the Heavens (1978).

Those who want to take the universe in smaller chunks might home in on the planets. The June 1976 issue of World Magazine (available through National Geographic for 70 cents) contains a punch-out planet-mobile. And if the solar system looms too large for you, concentrate on the moon alone: The Einstein Spacearium shop has a 50-cent Lunar Chart for sale.

Experts say the best all-around source for books, guides and astronomical gadgetry is in Barrington, N.J. (08007). Write the Edmund Scientific Co. there for a catalogue.

Hard-core Astronomy -- "Astronomy isn't like one of those villians in a play who raises his knife to kill and then stops to sing a song," says the NCA's McCracken. "You either do it or you don't. It's much more than just a hobby."

Membership in National Capital Astronomers is $18.50, which includes a subscription to Sky and Telescope; NCA's newsletter, Stardust; access to their telescope; monthly meetings, discussion groups, and lectures from National Aeronautics and Space Administration, Naval Observatory and university experts on anything from celestial photography to binary stars. (Write Robert Lynn, 7320 Baylor Ave., College Park, Md. 20740 for a membership application.)

Professional astronomers also will lecture at the Air and Space Museum's regular program, starting in January. Write to Special Presentations (Presentation Division, National Air and Space Museum) to be placed on their mailing list.

Whether your interest in astronomy is elementary or elegant, it can be sparked and bulwarked by Washington's many programs. And each is guaranteed to send you out of this world.