Meteorites fell into Cape Cod Bay on Saturday when a meteor exploded into a fireball about 30 miles up in the atmosphere.
Liam Peterson is a geochemist and a postdoctoral researcher at the Woods Hole Oceanographic Institution. He was disappointed that he didn’t see or hear the meteor, but he was able to take a very educated guess as to what the meteor's debris—called meteorites—might look like.
“If you think of a volcano, like in Iceland or like in Hawaii, those lavas that are coming out there are going to coarsely resemble what that meteorite probably looked like,” he said.
Peterson clarified the differences between a meteor, a fireball and a meteorite.
An object that crosses earth’s orbit becomes a meteor when it enters the atmosphere, he said. The meteor will then start to burn up and break into pieces—that’s the fireball.
“You have this little object that's going 75,000 miles an hour, goes through the atmosphere, and then it gets to a point where it can't basically withstand that force anymore and explodes,” he said. “And then you get that big fireball.”
And, in this case, a sonic boom.
Whatever pieces of the object survive the fireball and make it to earth are called meteorites.
Radar information aggregated by NASA shows that the meteorites fell about 15 miles north of Sandy Neck Beach in Barnstable. In cases like this, meteorites are usually the size of a piece of gravel you might find in a driveway, Peterson said.
But according to NASA, radar data shows unusually large meteorites for this particular event—up to multiple kilograms a piece.
Peterson said the meteorites in the bay are not likely to pose any ecological risk. Even if they were made of something toxic (which is highly unlikely), the bay is so big that it probably wouldn’t have an impact, Peterson said.
“On entry, the estimate is that it was about a yard in diameter,” he said. “Even if it was a pure contaminant—say it was like pure mercury—the mass of the body of water relative to the object that size, even if it fully dissolved, it's unlikely to constitute a significant contaminant source.”
A report on NASA’s website says most meteorites are "strongly attracted to a magnet,” and the ones in the bay could be reached with 100 feet of rope with a magnet on one end.
This has been repeated by local news outlets, but Peterson said it’s misleading.
“There's actually only about two percent of meteorites that we call iron meteorites or irons. Those would be the things that you could probably take a magnet to and stick it,” he said. “But for most things, we're talking about something that's going to be more like a rock that you'd find outside, and you're just not going to be able to stick a magnet to that.”
Peterson said the science behind NASA’s assertion is correct. It's true that all meteorites have some remnants of magnetism—but so do many rocks on earth that won't stick to magnets.
Peterson encouraged people to go to the American Meteorological Society website if they think they see a fireball or hear a sonic boom and make a report.
“It really helps scientists to identify potential flight trajectories and locations of these events,” he said.
For this most recent fireball event, 86 people made eye witness reports. One of those people was R. Schott, who caught the fireball on video. It looks like a falling star appearing briefly on the right side of the frame.
Now could be a more important time than ever to make eye witness reports. The first quarter of 2026 saw a surge in large fireball events, the American Meteorological Society wrote in an article from March. Experts at the organization don’t yet know why this is happening, but they want to find out.
According to the Massachusetts Meteorological Survey, only two meteorites have been recorded in Massachusetts that we know of. The first was found in Northampton in 1963, and the second in Barnstable in 2018.
The Lunar and Planetary Institute says a fragment of the Barnstable meteorite was found on a pile of rotting leaves surrounded by wild blueberry bushes on August 18. The main meteorite was found on September 11, and more fragments turned up in the area throughout the rest of the year.
If you heard or saw the fireball, CAI wants to hear from you. Call our newsroom: 508 548-9600 ext. 5.
