Wait…meteors can make noise?

Posted at 10:37 AM, Jan 17, 2018
and last updated 2018-01-17 11:22:50-05

MICHIGAN -- Tuesday night’s sonic boom and earthquake produced from a meteor tearing through the sky was quite the spectacle that could be seen across several states in the Great Lakes region. Along with it…a sonic boom that registered 2.0 on the Richter scale according to the United States Geological Survey (USGS). Did you know a meteor could be heard? Here’s how!

It all goes back to basic science. Things like density, molecules, and the all-important speed of this case, the speed of sound. Depending on temperature and exact composition of gases in our atmosphere (i.e. nitrogen/water vapor/oxygen/argon/etc.), the speed of sound can change. In general, the speed of sound at 32 degrees is around 740 miles per hour, but increases to about 770 mph around 70 degrees. Why? Because the molecules in the air move faster in warmer/less dense air, which allows the speed of sound to move faster. It’s worth noting that the speed of sound varies in different mediums. For example, it travels slower in air (gases), faster in liquids, and the fastest in solids…hence the immediate sound earthquakes make when rumbling through the solid rock and ground.

So how does all of this relate to the sound a meteor makes screaming through the earth’s atmosphere? The meteors, especially sizable ones (bigger than a grain of dust), can travel faster than the speed of sound. Once the sound barrier is broken (that is the meteor moves faster than the speed of sound), a shock wave is created that we hear as a loud noise or sonic boom. These booms can be heard before they are slowed below the speed of sound. Eyewitness reports of the meteor all say they heard the boom, but may not have heard it the entire time as it slowed below the speed of sound at some point. So yes…meteors can be heard.

As we talk about sonic booms and the speed of sound, the aircraft company Boeing has a concept design known as the “Son of Blackbird”. It’s a hypersonic strike aircraft that can reportedly go five times faster than the speed of sound. Wow! We call that Mach 5. Imagine the boom that would make!

The other question? Was the meteor large enough to impact somewhere and if so, where is it? That may be the next topic of this interesting story. It reportedly may have made it all the way to the surface (known as a meteorite if it did) in extreme southeast lower Michigan...somewhere close to the Ohio border. That said, the impact itself could have caused the register on the Richter scale as well.

Thanks to Mike Austin for the photo. If you'd like to see more photos or actual videos of this event, click here.