Every year in late May and early June, Great Smoky Mountains National Park comes alive with thousands of fireflies that flash synchronously to create a magnificent light show.

For visitors looking to catch the sparkling natural phenomenon, park officials have just announced the dates for this year's viewing at the Elkmont Campground: They will be from May 30 to June 6.

The event is so popular, however, you have to win a lottery to get access. Interested travelers can enter through the national park service’s lottery system from Friday, April 28 to Monday, May 1.

There will be 1,800 vehicle passes available through the lottery, and winners will be selected through a randomized computer drawing. There’s no charge to enter the lottery, but winners will be charged a $2.75 reservation fee after being notified.

The park service introduced limited shuttle service, which will take visitors from the Sugarlands Visitor Center to the campground during the eight days of the showing, back in 2006 to limit traffic congestion and provide a safe viewing experience.

While the park is home to at least 19 species of fireflies, the photinus carolinus are the only ones that can synchronize their flashing light patterns.

The lightning bugs, which are actually beetles, use the flashing pattern as a mating display.

No one is quite sure why this species synchronizes their flashes, according to the national park service, though park representatives say it could be due to competition between the male fireflies, or because the males believe they have a greater chance of being noticed if they all flash together.