A three-alarm forest fire in the White Mountains near Woodstock, New Hampshire was linked to reports of a meteorite strike, the Boston Globe reported yesterday.
A long exposure shot of the Perseid meteor shower over Villarejo de Salvanes, Spain in 2013. Photo: AP
On Tuesday night, one witness said that the day before “at 7:35PM, he was driving by and saw a meteor streak through the sky and crash,” Woodstock fire department Chief John MacKay told the paper. The blaze in the area later spread to between 22 to 25 surrounding acres of forest and more than 50 people, as well as two helicopters, were deployed to fight it.
“It’s not a large fire, but it’s a difficult fire because of the steepness of it, and the elevation,” MacKay added. As to whether the fire was started by a space rock, the fire chief told the Globe, “We can’t say yes or no.”
Disregarding whether the report of the meteorite was accurate, look: It’s reasonable to suspect some sort of connection. After all, rocks burn up in the atmosphere all the time — honestly, at a frequency that might make you nervous — and certainly look really hot while doing so. Pop-culture depictions of meteors also often depict them as flaming masses of semi-molten rock.
But the science suggests otherwise.
According to the American Meteor Society, while thousands of meteors each day are bright enough to be referred to as fireballs, only relatively large, slow-moving and sturdy meteors are likely to hit the ground without disintegrating during their passage through the atmosphere. These big ones are capable of transferring their kinetic energy to thermal energy, though this would result in a very hard to miss explosion of considerable size.
While there isn’t much data on the temperature of smaller meteorites that hit the ground, the society wrote, they probably aren’t glowing red-hot with energy.
When meteorites burn up in the atmosphere, they undergo ablation — a process in which the outermost layers of the falling object impact air molecules at high speed and are vaporised. The atmosphere actually sucks away much of the heat, per the AMS:
The ablation process, which occurs over the majority of the meteorite’s path, is a very efficient heat removal method, and was effectively copied for use during the early manned space flights for re-entry into the atmosphere. During the final free-fall portion of their flight, meteorites undergo very little frictional heating, and probably reach the ground at only slightly above ambient temperature.
Meteorites of less than 10 tonnes actually lose much of their speed when penetrating the atmosphere and then simply fall to earth at a terminal velocity of 322-644km/h, with terminal velocity occurring “at the point where the acceleration due to gravity is exactly offset by the deceleration due to atmospheric drag”.
As the Cornell University Astronomy Department notes, though, while rocky meteorites are poor heat conductors, anecdotal reports suggest some do hit the surface at least hot enough to singe grass. So it could theoretically start a fire.
“It’s not impossible, but it’s very, very unlikely and improbable,” University of New Hampshire physics professor John Gianforte told the Concord Monitor.
In 2016, Maryland firefighters retracted a claim that a blaze around a “crater 12-15 foot (3.7-4.6 meter) wide and 5-6 ft deep” was caused by a meteorite.
“There’s hiking trails through this area, so there is the possibility of a cigarette or a campfire,” MacKay told the Globe.