There is a place on Earth where an “everlasting storm” appears almost every night, averaging 28 lightning strikes per minute for up to 10 hours at a time. Known as Relámpago del Catatumbo — the Catatumbo Lightning — it can spark as many as 3,600 bolts in an hour. That’s one per second.

This storm lives above a swampy patch of northwestern Venezuela, where the Catatumbo River meets Lake Maracaibo, and has provided near-nightly light shows for thousands of years. Its original name was rib a-ba, or “river of fire,” given by indigenous people in the region. Thanks to the frequency and brightness of its lightning, visible from up to 250 miles away, the storm was later used by Caribbean sailors in colonial times, earning nicknames like “Lighthouse of Catatumbo” and “Maracaibo Beacon.”

The lightning has also played an even larger role in South American history, helping thwart at least two nocturnal invasions of Venezuela. The first was in 1595, when it illuminated ships led by Sir Francis Drake of England, revealing his surprise attack to Spanish soldiers in the city of Maracaibo. The other was during the Venezuelan War of Independence on July 24, 1823, when the lightning betrayed a Spanish fleet trying to sneak ashore, helping Adm. José Prudencio Padilla fend off the invaders.

So what causes such a powerful storm to develop in the same spot, up to 300 nights a year, for thousands of years? Why is its lightning so colorful? Why does it not seem to produce thunder? And why does it sometimes vanish, like its mysterious six-week disappearance in 2010?

The Catatumbo Lightning has sparked plenty of speculation over the centuries, including theories that it’s fueled by methane from Lake Maracaibo or that it’s a unique type of lightning. Although its exact origins are still hazy, scientists are pretty sure it’s regular lightning that just happens to occur far more frequently than anywhere else, due largely to local topography and wind patterns.

The Lake Maracaibo basin is surrounded on all but one side by mountains, pictured in the map below, that trap warm trade winds blowing in from the Caribbean Sea. These warm winds then crash into cool air spilling down from the Andes, forcing them upward until they condense into thunderclouds. All this happens above a large lake whose water evaporates vigorously under the Venezuelan sun, offering a steady supply of updrafts. The whole region is like a big thunderstorm machine.

But what about the methane? There are major oil deposits below Lake Maracaibo, and methane is known to bubble up from certain parts of the lake — especially from bogs near three epicenters of storm activity. Some experts think this methane boosts the conductivity of air above the lake, essentially greasing the wheels for more lightning. That hasn’t been proven, though, and some experts also doubt methane is significant compared with the large-scale atmospheric forces at work.

The colors of Catatumbo Lightning have similarly been attributed to methane, but that theory is even shakier. People often see the storm from 30 miles away, and dust or water vapor floating near the surface can distort faraway light, adding color to lightning much like sunsets and sunrises.

Another common Maracaibo myth also boils down to distance: the apparent lack of thunder. Observers have long speculated the storm generates silent lightning, but it doesn’t. All lightning produces thunder, whether it’s cloud-to-ground, intracloud or anything else. Sound just doesn’t travel as far as light, and it’s rare to hear thunder if you’re more than 15 miles away from the lightning.

Some scientists say the Catatumbo Lightning helps replenish Earth’s ozone layer, but that’s yet another cloudy claim. The lightning bolts do coax oxygen in the air to form ozone, but it’s unclear whether that ozone ever drifts high enough to reach the stratospheric ozone layer.

Although the Catatumbo Lightning doesn’t appear every night, it’s not known for taking extended breaks. That’s why people were alarmed when it vanished for about six weeks in early 2010.

The disappearance began in January of that year, apparently due to El Niño. The phenomenon had been meddling with weather around the world, including a severe drought in Venezuela that virtually eliminated rainfall for weeks. Rivers dried up, and by March there still hadn’t been a single night of Catatumbo Lightning. Before that, the longest-known hiatus was in 1906, after an 8.8-magnitude earthquake had caused a tsunami. Even then, however, the storms returned in three weeks.

“I look for it every night but there is nothing,” a local schoolteacher told the Guardian in 2010. “It has always been with us,” a fisherman added. “It guides us at night, like a lighthouse. We miss it.”

The rain and lightning eventually returned by April 2010, but some locals fear the episode could be repeated. Not only might another El Niño starve the area of rain — the Pacific Ocean has been flirting with El Niño conditions lately, for example — but the growth of man-made climate change can encourage stronger cycles of rainfall and drought in the region. And on top of that, deforestation and agriculture have added clouds of silt to the Catatumbo River and nearby lagoons, which experts like environmentalist Erik Quiroga blame for weaker lightning shows even in non-drought years.

“This is a unique gift,” he tells the Guardian, “and we are at risk of losing it.”

Not everyone agrees the gift is in trouble, though. University of Zulia researcher Angel Muñoz told Slate in 2011 “we have no scientific evidence the Catatumbo lightning is disappearing,” and added it might be intensifying due to extra methane from oil drilling at Lake Maracaibo. Either way, it’s widely agreed the storm is a natural wonder and a national treasure. Quiroga has been trying since 2002 to get the area declared a UNESCO World Heritage site, and while that’s proved difficult, he did recently succeed in lobbying for a Guinness world record: most lightning bolts per square kilometer per year.