When a bright fireball raced across the sky over Alaska last spring, scientists expected cameras and satellites to reveal exactly where it came from and where any pieces might have landed.
Instead, many of those systems missed important details.
Fortunately, the fireball left behind another clue—powerful low-frequency sound waves that traveled hundreds of kilometers through the atmosphere.
Using these sounds, along with tiny ground vibrations, weather radar and videos shared by members of the public, researchers were able to reconstruct the fireball’s journey through the sky.
Their study, published in the Journal of Geophysical Research: Planets, shows that “listening” to a meteor can sometimes be just as useful as seeing it.
The investigation began on the same day the fireball appeared. Logan Scamfer, then a research assistant at the University of Alaska Fairbanks, noticed unusual signals in data collected by earthquake-monitoring stations.
At first, the signals did not look like normal earthquakes. As he examined more monitoring stations across Alaska, he found the same strange pattern appearing again and again.
He also discovered a clear “N-wave,” a special sound pattern that is often produced by shock waves from fast-moving objects. This made him suspect that a meteor had entered Earth’s atmosphere.
Later that day, news reports confirmed that many people had seen a bright fireball crossing the sky.
A month later, Scamfer began an internship at Sandia National Laboratories, where he worked with physicist Elizabeth Silber, an expert in studying meteors using infrasound. Infrasound is a type of very low-frequency sound that is too deep for people to hear but can travel great distances.
Because cameras and satellites did not fully capture this event, the researchers decided to rely mainly on the sound waves and ground vibrations left behind.
Alaska turned out to be the perfect place for this work. The state has a large network of sensors that normally monitor earthquakes and volcanoes. These same instruments also recorded the pressure waves created as the meteoroid sped through the atmosphere at hypersonic speed.
In total, 57 instruments detected the event, including earthquake sensors and infrasound stations. Some picked up the signals from as far as 580 kilometers away.
By studying the timing of these signals, the researchers worked out the fireball’s flight path, where it broke apart and the area where meteorite fragments probably landed. They passed this information to a NASA scientist, who used Doppler weather radar to identify the cloud of falling debris.
The team also compared their results with dashcam and security camera videos shared by citizen scientists. These independent observations helped confirm and improve their calculations.
The researchers estimate the meteoroid entered Earth’s atmosphere at an angle of about 19 degrees and traveled between 80,000 and 90,000 kilometers per hour. It released energy equal to about 38 tons of TNT before breaking apart. They also believe it most likely came from the main asteroid belt between Mars and Jupiter.
The study marks the first known time scientists have successfully located meteorite debris on weather radar using guidance based mainly on sound and ground vibration data. This new approach could become an important tool for planetary defense, especially when fireballs appear in daylight or in areas where cameras cannot capture them clearly.
By combining sound, seismic signals, radar and public videos, scientists have shown that even when a fireball cannot be seen well, it can still tell its story—if researchers know how to listen.
