We've come a long way since the days of believing that lightning bolts were the work of angry gods, but some natural events continue to mystify us — including black holes, supernovas, the Marfa lights, the Bermuda Triangle, and the Taos Hum. Despite scientists' best efforts, there are many myths and legends surrounding unexplained natural events. Here are five events that continue to elude explanation.

1 of 5 Animal migration Domingez/iStockphoto. Many animals migrate thousands of miles of land and sea, all without the use of a GPS device. How do animals take these amazing journeys without getting lost? No one really knows, though there are many theories. According to an article in The Independent that focused on pigeon migration, some believe the birds navigate the Earth using visual landmarks or their sense of smell to determine their location. More bizarre-sounding theories include the concept that pigeons use magnetism to determine if they’re north or south of home; another is that the pigeons use morphic resonance, a theory by Rupert Sheldrake, to refer to what he calls the "the basis of memory in nature ... the idea of mysterious telepathy-type interconnections between organisms and of collective memories within species."

2 of 5 The Naga fireballs petdcat/iStockphoto. Each year, hundreds of fireballs spontaneously explode out of Thailand’s Mekong River. Known as “bung fai paya nak” or “Naga fireballs,” they have appeared on the “late autumn night of the full moon at the end of the Buddhist Lent for as long as anyone can remember,” according to a 2002 Time magazine story about the phenomenon. Some believe the balls come from the breath of Naga, a mythical serpent that haunts the river. (Locals use old grainy pictures and postcards of the mythical beast to prove its presence to tourists.) Others believe the fireballs are actually pockets of methane bubbling up from the river, but many locals remain convinced that the fireballs are of a supernatural origin.

3 of 5 The Tunguska event Wikimedia Commons. In June 1908, a ball of fire exploded in a remote area of Russia, shaking the ground and instantly flattening 770 square miles of forest. Known as the Tunguska event because of its close proximity to a river of the same name, the blast reached 15 megatons of energy, about a thousand times more powerful than the Hiroshima bomb. Recent research suggests a meteor is to blame, as evidenced by a nearby lake that some scientists believe was created by the meteor’s impact. However, other scientists believe the lake was there before the event. What is certain is that the event was the most powerful natural explosion in recent history.

4 of 5 Earthquake lights YouTube. These are mostly white or bluish flashes that precede large earthquakes and last for several seconds. They have been reported infrequently for hundreds of years, according to the U.S. Geological Survey. It wasn't until the 1960s, when people took pictures of this phenomenon during the Matsushiro earthquakes, that the scientific community started to take it seriously. Since then, scientists have created many theories for the origin of the lights, involving everything from piezoelectricity and frictional heating to phosphine gas emissions and electrokinetics. But most recently scientists suggested that the lights are caused by pre-earthquake elements that awaken the natural electrical charge of rocks, causing them to sparkle and glow.