FILED AWAY in an exhibit hall off the pendulum's beaten path, "Celestial Images" won't draw any more crowd than the night sky does.

At the Museum of American History, this show of star charts and celestial globes from 1500 to 1900 belongs to those who memorize the constellations and have gotten at least one stiff neck from looking up.

As we're reminded here, those constellations are set in neither stone nor sky. They are merely conventions -- although they are old ones. In his star catalogue of about 150 A.D., Ptolemy of Egypt grouped the stars visible from Alexandria into 48 constellations we still use, despite attempts to rename them.

In the 1600s, following a tradition dating back to Augustine, Julius Schiller, a devout Catholic, reassigned religious personas to Ptolemy's pagan constellations. He made the lusty Cassiopeia into a contrite Mary Magdalene. St. Joseph replaced Orion; St. Helen stood in for Cygnus; Eridanus, the river, became the Red Sea being crossed by the Israelites. Needless to say, Schiller's names didn't stick. But his engravings, on display here, have endured in beautiful pastels.

Other constellations you've probably never heard of are The Bust of Columbus (near Hydra) and the Flying Squirrel (just above Perseus). These can be found on America's first star chart, the "Mercator Map of the Starry Heavens," published in Boston in 1810.

In all there are 39 items, combining art and science, artfully. Two woodcuts here on which Albrecht Durer collaborated in 1515 are considered the earliest extant flat star charts.

The "orrery" -- of which there are several on display -- turns out to be not an eagle's nest or some such, but a clockwork model of the solar system. That name comes from Charles Boyle, fourth earl of Orrery, who commissioned one in 1712.

And a "cometarium" may come in handy for charting Halley's comet. Used in England in 1758, this simple compass device was a drawing-room toy, in the days when there were drawing rooms.

It would've been a lot easier to learn the names of the constellations then, when our view of the sky was simpler and less serious. Modern star charts lack the connect-the-dot outlines that give the constellations human or animal form. But in these early astronomical charts, cherubs adorn the phases of the moon and the sun sports a have-a-nice-day face.

CELESTIAL IMAGES: ASTRONOMICAL CHARTS, 1500- 1900 -- At the Museum of American History through August 23.