Gerard Butler made an appearance at NASA Wallops rocket launch

People who attended the rocket launch at Wallops Flight Facility Visitors Center on Wednesday might have caught a surprise celebrity sighting. 

Actor Gerard Butler, known for roles like "300" and "Olympus Has Fallen," attended the Antares rocket launch on April 17.

NASA Wallops on Virginia's Eastern Shore saw a huge crowd for the afternoon launch with an estimated 4,500 people at the visitors center alone, said facility spokesman Keith Kohler in a previous interview withDelmarva Now.

The NG-11 mission, part of Northrop Grumman’s Antares program, was successfully launched at 4:46 p.m. at the NASA Wallops Virginia facility. It marked the 10th success in the six years since the Antares program arrived at Wallops. 

The Cygnus spacecrafts carry cargo to the ISS orbits about 200 to 250 miles from Earth. The spacecraft carried food, clothing and equipment to the station, plus some science experiments.

This rocket also has satellites on board, many through different school and college programs.

Excited launch attendees were able to snap a photo with Butler and shared it on social media. 

"This is @NASA! NASA Langley Director Dave Bowles got to hang with actor @GerardButler, who starred in the movie “300,” during today’s rocket launch @NASA_Wallops. Congrats to the students, engineers and scientists who made it happen," NASA Langley Research Center posted on its Twitter. 

Instagram user Susan Campbell (@suesuelc) captioned her photo: "Met Gerard Butler today at the #cygnus launch at Wallops!" 

Twitter user April Phillips (@AprilPh16530904) also shared her excitement, posting a photo of Butler with a few other attendees. 

"Everyone loves a launch! @GerardButler is here at watch @antares blast off with a 7600 lb. payload, including 40 tiny #moustronauts," Phillips posted on Twitter. 

Radio stations 96.5 and 101.5 CTG shared another photo of Butler.

"Everyone loves a rocket launch from the NASA's Wallops Flight Facility including actor Gerard Butler. #CTGVariety #GoWallops," the radio station wrote on its Facebook page.

Background:Crowds mob successful daytime rocket launch from NASA Wallops

More:NASA Cygnus spacecraft launched from Wallops reaches ISS

More:Darth Vader and more will roam Va. Shore at first ever Comicon

Reporter Jenna Miller contributed to this report.

Reach reporter Meg Ryan at mryan@delmarvanow.com