CHARLESTOWN — After years of planning and fundraising, the Frosty Drew Nature Center and Observatory at Ninigret Park is about to break ground on an innovative sky theater that will seat 49 people — and enable observers to view the cosmos using the facility’s 7-foot telescope.

A groundbreaking date of Sept. 6 has been set for the project, which will involve the construction of a 840-square-foot building adjacent to the Nature Center across from the observatory. The theater will cost about $100,000, and could be completed as soon as three to four months, according to Holly Eaves – president of the board of the Frosty Drew Memorial Fund.

“It’s very exciting,’’ Eaves said this week.

Not only will the theater enable hundreds more people to enjoy the observatory’s telescope at any given time, including the disabled, but it will also open tremendous new opportunities for creative, educational programming, Eaves said.

A sky theater is different from a planetarium in that it projects real data and images onto an overhead screen, as opposed to simulated light shows. There are only a handful of such theaters in the United States, making the one planned for Ninigret Park somewhat of a unique attraction, according to Les Coleman of Westerly — one of the project’s planners and the former director of the Observatory.

People in the sky theater get to see what the observatory’s telescope spies thanks to a small camera on the instrument’s eyepiece, which will transmit images digitally to a computer in the theater. In addition, Coleman said he will be able to create previews of events in the cosmos using data from NASA’s Hubble telescope.

Educational programs can also be created using recorded images of past events, Coleman noted. These programs will enable school children to benefit from the observatory since they can be played at any time, as opposed to just on Friday nights when the telescope is used, he said.

“The kids won’t have to be up at three in the morning,’’ Coleman said.

For Coleman, the sky theater is the culmination of an effort that began nearly seven years ago and saw numerous delays and false starts; Frosty Drew’s Web site notes an earlier groundbreaking set for March 2007. First, the organization had to raise money for the project — a task made easier when the Champlin Foundation awarded Frosty Drew an $80,000 grant in 2006.

Then there was the matter of getting necessary approvals, a process that took about two years, according to Eaves.

Over time, the estimated total cost of construction decreased from approximately $130,000 to $100,000, said Eaves. This is a welcome development since now there is enough money for seating and other necessary fixtures, she said.

The observatory was created by the Frosty Drew Memorial Fund, a non-profit established in honor of Edwin “Frosty” Drew upon his death from polio at the age of 28 in 1976. A graduate of Brown University, Drew helped to prevent the construction of a nuclear power plant at the former Charlestown Naval Air Station, which instead became a wildlife refuge and public park.

Drew’s passion are reflected in the non-profit’s mission, which is to provide to environmental stewardship and education for people of all ages, with a special emphasis on marine life and the stars. The nature center was the first project built at Ninigret and during a “star party’’ to celebrate it, the idea for the observatory was born.

Today, the observatory has a telescope that draws up to 50 people on Friday nights when, weather permitting, it is used. It could be used more, but Coleman said staffing is an issue.

The location of the observatory, nestled in a wildlife refuge near the sea, is hailed by star lovers because there is little light pollution in the area. Indeed, Charlestown has been known to have the “darkest skies’’ on the east coast from northern Georgia to Maine, Coleman said.

To help kick off the sky theater, a benefit wine tasting and auction is set for Sept. 21 at the Celestial Cafe in Exeter. The event runs from 4 to 6 p.m. Tickets cost $30 apiece.