Science has taught us so much about the world and has led to so many technological innovations, that when you step back and consider it all, it’s sort of mind-blowing. But science has its limits, too.

For every answer it gives us, there’s a problem that leaves scientists stumped. Check out some of these crazy natural phenomena that are still huge question marks in the science books…

1. Scientists have consistently observed strange flashes of light that precede volcanic eruptions. They suspect the coming eruption shifts electrical charges in the surrounding geological formations, but that hypothesis has yet to be conclusively proven.

2. Like volcanic lights, earthquakes are also sometimes preceded by the appearance of white or blueish flashes of light lasting only a few seconds at most. Electrokinetics, piezoelectricity, and frictional heating have all been offered as explanations, but scientists have been unable to prove any of them are the actual cause.

3. Sailing stones are rocks that appear to move themselves, leaving a trail in their wake. The stones can even change course or flip themselves over. Some scientists blame strong winds for the movement but that idea hasn’t been conclusively proven.

4. Since at least the 1940s, a strange light phenomenon has occurred in Hessdalen Valley, Norway. 10-20 times per year, observers see a white or yellow light floating above the ground in the distance. Numerous theories about the light’s origin have been offered but none have been proven.

5. Animal migration is a part of the natural world that we all just accept, but scientists are still unsure how such complex patterns of movement become hardwired in the brains of such a wide range of species like birds, fish, insects, and mammals.

6. While animal migration in general remains mysterious, the migration pattern of the monarch butterfly is particularly noteworthy. Its lifespan is only 6 months, which means each new generation of butterflies migrates without an older generation to lead the way. Scientists know the sensory antennae are crucial for successful migration, but they aren’t sure how they help.

7. “Naga Fireballs,” are strange natural phenomena that occur on the Mekong river in Laos and Thailand. Fiery red balls of light appear to rise from the river, but no decisive scientific explanation for them has ever been offered.

8. “Fairy circles” are barren circular patches that appear in grasslands in southwest Africa. They range in diameter from 2 to 20 meters and were long suspected to be caused by a sand termite, but scientists have found that the circles occur over a much wider area than the termite lives in.

9. The Loch Ness monster is one of the most famous crypto-creatures in the world. Though most alleged photographs of Nessie have been exposed as fakes, sightings of the monster have been consistently reported for years. 

10. The Bermuda Triangle is infamous for the number of planes and ships that have disappeared in the area. Theories ranging from UFOs to methane bubbling up from the ocean have been offered as reasons for the disappearances, but scientists have yet to find anything out of the ordinary about the triangle.

11. Ice circles, also known as ice discs, are rare phenomena that occur in slow moving water at freezing temperatures. They range from a few feet to over 50 feet in diameter. Scientists suspect they’re formed by eddy currents, but have been unable to demonstrate how that process would actually work.

12. Taos, New Mexico is famous for its hum. About 2% of the town’s population can consistently hear a low, droning buzz with no known source. There are other places in the world that have the same phenomena, but there are no obvious connections between locales where the hums occur.

13. Less an unexplained than simply a weird natural phenomenon, the moon appears much larger when it’s on the horizon than it does when further up in the sky. While from the same vantage point, the moon measures the same no matter where it is, the horizon causes forced perspective and we perceive the moon as larger.

14. Ball lightning happens during storms when electricity clusters in a spherical or oblong shape, and it lasts significantly longer than regular lightning. Scientists still aren’t sure how or why this happens though numerous competing theories abound. 

15. Synchronous fireflies live in Great Smoky Mountain National Park in Tennessee, and for a few weeks each year they coordinate and synchronize their flashing patterns. The mechanism and reason for the synchronization remain a mystery.

16. Everybody knows that cats purr when you pet them or when they’re happy, but they also purr when eating and when giving birth. Scientists still aren’t sure why the response developed or what it means in such different contexts.

17. Male humpback whales’ low-pitched “songs” were once thought to attract females, but scientists found that they’re used grab the attention of other males too. Plus, the whales each have slightly different songs, and they can teach others to sing theirs. Scientists have yet to out why they do it all. 

18. The origin of the universe is one of the biggest scientific questions there is. Though the Big Bang is the prevailing theory, and there’s evidence to support it, what immediately preceded the Big Bang remains a mystery.

19. The Mapimí Silent Zone is a patch of desert in Durango, Mexico that is described as unusually silent and was rumored for years to be an area where radio signals couldn’t be received. It also has a penchant for attracting strange debris, like a malfunctioning test missile launched in Utah and the Apollo rocket boosters.

20. Jellyfish Lake is connected to the ocean via underground channels, and is named for the jellyfish that frequently traverse them. However, between 1998 and 2000 for no reason that scientists were ever able to deduce, the jellyfish stopped travelling to the lake completely. 

21. A NASA probe orbiting Saturn captured this image of a hurricane on the planet. The eye of the storm was about 1,250 miles in diameter and the “winds” moved as fast as 330 miles per hour. Given what’s known about the makeup of the planet and its atmosphere, scientists are at a loss to explain how the storm even started.

22. About 2,000 whales beach themselves each year, and in most cases they die. The thing that scientists are unable to explain is that in some cases it appears that the whales do it to themselves on purpose.

23. People say it’s raining cats and dogs, but in 2000 in Ethiopia it rained fish. Similar incidents have occurred elsewhere, and the accepted explanation is that the fish are swept out of the ocean by a storm when it’s most powerful, but the odd part is that when it happens, it only ever seems to rain one species at a time.

24. The sun’s corona actually gets hotter than the surface of the sun itself, and scientists are at a loss as to how or why. While the surface of the sun is about 5800 degrees Kelvin, the corona reaches temperatures of 1-3 million degrees Kelvin.

25. Like the Loch Ness monster, Bigfoot (or the yeti or any other permutation of the missing-link) is a longtime favorite of cryptozoologists. Dismissed as a myth, sightings are still regularly reported and some speculate the sightings could be of members of an isolated ancient species of great apes.

Wow… some of that stuff is pretty wild! I wonder how many of these will be explained by science one day, and how many will stay mysteries forever…

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