Hatter Planetarium, built in 1966 with a generous gift from Mr. and Mrs. George G. Hatter, serves the Gettysburg College campus and surrounding community with free programs that explore a variety of astronomy topics. The planetarium is located in the north wing of Masters Hall on the Gettysburg College campus.

Planetarium features:

- A 32-foot square chamber topped by a hemispherical projection dome 30 feet in diameter, which serves as a projection screen;
- A Spitz A-3P planetarium projector located at the center of the dome that simulates the sky as it appears at any time of day or night ... for any time in the past or future ... and from any point on the Earth (celestial motions can also be accelerated, so that centuries can be observed in the span of minutes);
- Analytical scales and diagrams that are projected to explain how man studies the heavens (a celestial coordinate system, ecliptic, and meridian projectors complement the main projector to allow accurate sky measurements); and
- a sophisticated sound system, auxiliary projection system, and other devices that allow special effects such as twilight, meteor shows, comets and aurora.

The facility is used to illustrate the motions of the heavens to introductory astronomy classes, and with rows of seats circling the room to provide comfortably for one hundred, it's also the location of The Sky this Month and other shows that are open to the community, as well as to members of Gettysburg College; many pre-school, elementary and high school groups visit Hatter Planetarium during the school year for talks and demonstrations on the heavens.