It's that time of year again when thousands flock to the mountains to see the synchronous fireflies light up the night sky.

There is no other event like it in the Western Hemisphere, which is partially why so many are baffled by it, and also why so many head to East Tennessee in the last few weeks of the spring season. The synchronous fireflies are a phenomenon that most just have to see to believe.

Which is why people travel from not only across the country, but also from across the globe to see them light up in unison.

Chris Clark drove down from Detroit, Michigan to try to capture the show with his camera.

"I've heard about it numerous time before, and it's one of those things I've been trying to do to scratch off my bucket list," Clark said.

Susan Miller and her two friends drove from Cleveland, Tennessee to catch the bugs sync up for the first time.

"That's astounding. Astounding," she said.

Mary Ann Ryan made the drive from Chicago, Illinois to write an article about it for a local paper.

"To let the community know about such an unusual event," Ryan explained.

The fireflies are so popular that thousands try every year to get the passes the national park gives out, but with a first come, first served system of awarding tickets, the park's online and phone system would routinely crash when tens of thousands of people would try to get their tickets at the same time. However, this year the park implemented a lottery system to award the tickets, plus spread the time to enter for those tickets out across three days. Once the entry time period was closed, the park used a computer to pick names at random to award the tickets instead of the first come, first served method.

Dana Soehn with the Great Smoky Mountain National Park said this year's lottery system made things less frustrating for everyone involved.

"We would have over 15,000 people trying to secure their pass on the same day. And we often crashed our phone lines, not only at our offices, but also at recreation.gov," Soehn said.

The fireflies typically light up during the last week of May and into the first week of June and can be most easily seen in the Elkmont campground area.

The park has issued a statement on proper etiquette for those who have a ticket to see the fireflies light up at the campground. You can get the full details of what to do and what to expect while viewing the fireflies by visiting the links included in this article.