RALEIGH — Over the past two decades, Betsy Bennett transformed the N.C. Museum of Natural Sciences from a drab annex to a nationally recognized science center and the state’s most visited museum.

On Friday, she announced her plan to retire at the end of the year, following this spring’s triumphant opening of the Nature Research Center, a $56 million expansion. The museum will launch a national search for Bennett’s replacement, and admirers say it will be difficult to fill her shoes.

“She has nurtured the museum to levels beyond which no one could have dreamed,” said Tom Earnhardt, former president of the museum’s board. “At the same time, she has really raised the bar across the state for science education.”

Bennett, 68, has been described as a force of nature. She is a petite dynamo who forged coalitions, lured donors and found new research partners for a museum that wows visitors with its whale skeletons and the scary-looking Acrocanthosaurus dinosaur.

“This has been the most fun job anybody could have had,” Bennett said Friday in a meeting with dozens of staff members, who let out a collective gasp upon her announcement. They stood and applauded, some wiping away tears.

The free museum typically draws more than 700,000 visitors annually and hosts groups of wide-eyed schoolchildren daily. This year, its reach extended well beyond Jones Street with the April debut of the Nature Research Center with interactive labs and the Daily Planet, a giant globe that can beam multimedia science programs into schools across North Carolina.

In its first two months, the Nature Research Center attracted 300,000 visitors, putting the museum on track to exceed a million visitors in 2012. “It’s just been amazing,” Bennett said. “People love it, and they’re engaged.”

Last month, the museum brought out big telescopes for the public to view the transit of Venus across the face of the sun. One hundred people were expected, but 1,300 showed up.

On Friday afternoon, the place buzzed with activity as families and summer visitors tried their hand at experiments and wandered among the exhibits. In the Daily Planet, a scientist presented a segment called “The Earth’s Coolest Bugs: The Hidden World of Hoppers.”

Joanna Massoth, a sixth grade teacher at Chatham Middle School, led her daughter through the Nature Research Center. Last month, she took her class there on a field trip.

“They were just astounded,” Massoth said. “It’s fabulous having all the interactive exhibits.”

Snagging ‘Acro’

Bennett was born and reared in Birmingham, Ala., and from a young age had an intense connection to the natural world. She is an avid hiker, kayaker and fly fisherwoman and enjoys wilderness adventures with her husband and two grown children.

Educated at Hollins University and the University of Virginia, Bennett became a science and math teacher. She and her family landed in Charlotte, where she served on the Charlotte-Mecklenburg school board for seven years.

She got her start in museums at Discovery Place in Charlotte, where she occasionally dressed as Madame Curie to demonstrate physics experiments. In 1990, she arrived at the N.C. Museum of Natural Sciences with big plans.

The century-old museum had vast collections but not much of a presence. It was tucked in an agriculture building, cramped and dark. Its main attraction was a python named George.

Soon Bennett began raising private money and seeking legislative appropriations for a $71 million building, and she set about plucking acquisitions to fill it. In 1997, she bid more than $7 million on a massive T-Rex fossil on auction at Sotheby’s in New York. Though the North Carolina museum and its anonymous donor didn’t get that famous dinosaur, they nabbed “Acro,” the Acrocanthosaurus that would become an icon.

Branching out

The museum opened in 2000 to rave reviews, but it wasn’t long before Bennett began looking ahead to the next chapter. The Nature Research Center was years in the planning and has set a standard for technology and outreach among science museums. While the Daily Planet can connect to school classrooms, it can also link up with scientists around the globe.

And while the main museum has Acro, the new wing has its own dazzling displays, including a collection of North Carolina emeralds that are among the largest ever unearthed in North America.

The Nature Research Center allows visitors to watch and interact with scientists as they work. Museum staff have launched citizen science projects on moths, water scorpions and other topics to bring the process of research alive.

Observers say North Carolina’s museum is clearly on the national and international radar. In 2014, the museum will help host a conference for the Association of Science-Technology Centers, an international organization for science museums.

Bennett said the timing was right for her to retire. The museum is stable, it has a great staff and solid community support, she said. The next director will be able to seize the possibilities for global outreach and ongoing linkage to schools.

“There’s no museum in the country like this,” Bennett said. “Realizing that potential, I think, will be very exciting.”

Dee Freeman, the state secretary of environment and natural resources, has set up a search committee and hopes to name Bennett’s successor before she departs at the end of the year.

‘A great future’

John McMillan, Raleigh attorney and longtime supporter of the museum, said there’s no question the museum is in a position to attract a top-flight candidate as its next director.

“Betsy brought so much energy and enthusiasm to the museum,” McMillan said. “That permeates the staff, and they’re still there. I think the museum has a great future.”

For the next six months, Bennett said the museum will focus on its social media strategy and wrap up the private fundraising for the Nature Research Center. She also hopes to win grant money to build an overnight facility for school groups at Prairie Ridge, the museum’s 45-acre ecostation in West Raleigh.

When she told her staff of her pending retirement Friday, she joked that she would be really depressed next January when she’s no longer the director.

“Part of me will always be at the museum,” Bennett said.

Stancill: 919-829-4559