The day was winding down in Denver, Colorado. It was Monday night, around 9:00 p.m., and residents of the city were probably starting to think about turning in. But something truly strange happened that likely shook them awake almost instantly. And it’s not the first time, or the first place, that it’s happened this year.
All across the world, from the United States to Australia, people have been reporting similar experiences. In all, 64 occurrences of the bizarre phenomenon have been reported. And as of yet, no one has been able to come up with a satisfactory explanation for it. But what is this weird happening?
To put it bluntly, they’re loud booms. The most recent happened in Colorado on November 21, 2017. According to CBS Denver, residents in a number of areas of the city reported that the explosions were loud enough to “shake windows and rattle walls.” And while some of the booms have been explained, many more remain a complete mystery.
The first boom of 2017 was recorded in Connecticut on January 3. Since then there has been a steady stream of reports from all corners of the globe about other mysterious noises. And many of them have left scientists and meteorologists baffled. There just doesn’t seem to be a satisfactory explanation for the noises.
A number of theories have been discounted, though. In Denver, CBS meteorologist Chris Spears wondered if the continuing Leonid meteor shower might have something to do with the loud sounds. The shower happens when Earth passes through the debris trail from a comet known as Tempel-Tuttle. They’re called the Leonids because they look like they’re coming from the constellation Leo.
But after Spears spoke to weather watcher and astronomy expert Ron Hranac, it became clear that that couldn’t be the case. The Leonid meteors are incredibly small, most of them no larger than the size of a pea. While they do burn up in the Earth’s atmosphere, leaving bright trails behind them in the process, they simply don’t have enough mass to impact on the ground. So what else could explain the odd sounds?
Another suggestion was put forward: could the loud noises in Colorado have been caused by military jets breaking the sound barrier? When planes go supersonic, they create shock waves, which sound a lot like an explosion on the ground below. Maybe this was the reason for the booms on that Monday night?
But a little more digging proved that that wasn’t it, either. Spears called the nearest place jets could have come from to find out more. All of the planes from Buckley Air Force Base were back on the ground by just gone 8:00 p.m. that night. And that was well before the residents of Denver began to report hearing the explosions in the sky.
While it wasn’t the case in Denver, other booms have in fact been caused by supersonic flight. One such instance, in Central Florida in May, was caused by a NASA mission returning to the Kennedy Space Center. That was confirmed by a tweet from the official NASA account. Perhaps, though, there was an explanation for the Colorado noises from somewhere much closer to home?
After discounting sonic booms and crashing meteors, then, Spears wondered if an earthquake could have been responsible for the bizarre sounds. However, a call to the United States Geological Survey put paid to that guess, too. Although the USGS did pick up a small amount of noise at the Rocky Mountain Arsenal at time of the explosions, that was most likely from a passing goods train.
The plot seemed to thicken a little when it was revealed that someone had spotted a fireball in the sky that night. But that couldn’t have caused the din either. The fireball appeared much later on in the night, at around 11:30 p.m. That’s more than two hours from the first reports of the booms.
Then, as the days went by, more information came to light that offered a disappointingly mundane reason for the explosions that had rocked Colorado. Rather than coming from space, or from deep underground, the actual cause could well be something as simple as a small industrial accident.
The day after the booms had been heard, representatives of the Colorado Oil and Gas Conservation Commission believed they had the answer. Near where many of the city’s residents had reported hearing the noises, an empty storage tank had suffered a glitch. That had led to pressure building up inside the tank.
And when that pressure became too much, the inevitable happened. The lid of the tank blew off. Luckily, the tank was new and empty. But a pressurized container popping its top could well explain why a lot of residents reported hearing the loud bangs on that Monday night. And there was more evidence to support the claim to come.
The oil and gas company that owned the tank filed a report about the accident. It stated that the covering of the tank was “compromised.” That certainly sounds like a solid enough explanation for the booms that were heard in Colorado. However, the officials who revealed the details of the tank accident can’t be sure that that’s what to blame.
And it certainly doesn’t explain the other noises that have been heard around the world. Some of them have been explained in a variety of ways, but more still remain mysterious. And there are some in the scientific community who believe that these strange noises are becoming more and more frequent as well.
Perhaps the most famous of the incidents has become known as the Bama Boom. It happened on November 14, 2017, in Alabama, and as of yet no one knows what caused it. While the USGS did pick up some seismic activity around the time that the noise occurred, it went on to confirm that it wasn’t an earthquake that was behind the disturbance.
Again, the Leonids were proposed as one of the possible causes, but speaking to ABC 3340, NASA’s head of the Meteoroid Environment Office, Bill Cooke, said that was unlikely. He pointed to the possibility that a bolide could have been behind the boom. Bolides are large meteors that blow up in the Earth’s atmosphere, but they’re not part of the Leonid storm.
A large number of the booms that have been heard over the past 12 months remain unexplained. Much like the so-called Bama Boom, there are best-guesses as to what caused them, but hard scientific evidence remains thin on the ground. From Wales to Wisconsin, though, people around the globe have been reporting almost exactly the same thing.
It’s true that the booms in Colorado might have been explained away by a simple industrial accident, but it’s highly likely that the strange sounds around the rest of the world are going to continue to capture the public imagination. And if the noises really are becoming more regular, perhaps in 2018 we’ll finally figure out what’s been causing them all.