On any given night it’s possible to see a few meteors if you watch the sky from a dark location, and at certain times of year meteor showers occur, when tens and even hundreds of meteors can be seen each hour. But only rarely will you see a fireball — an exceptionally bright meteor that leaves a glowing trail behind it or visibly explodes or fragments during its descent. Fireballs of this kind — also called bolides — are unpredictable, and can indicate an object that was large enough to have made it to the ground as a meteorite.
Just after sunset this evening, as I was waiting for the train at Concord Station, I saw a fireball in the northwest, descending almost vertically until its trail disappeared behind a building. It’s impossible for a single observer to correctly estimate the true distance and altitude of an object of this kind, but if enough observers see the same event from different locations, then triangulation is indeed possible. And that’s where the fireball reporting system of the American Meteor Society comes in.
If you ever see a fireball, note down the time, the compass direction, the fireball’s height above the horizon and its direction of travel, its color and whether it visibly broke up or exploded — and then head over to the AMS’s fireball reporting page. If you fill in all the details of your observation it will be added to the list of pending reports, and then if other observers in other locations saw the same thing it will be designated an event — a verified fireball — and the fun work will begin to identify the object’s true location and course through the atmosphere.
As of this writing, the fireball I saw has been entered and classified as pending report #128372, and it looks like one other person in Northfield, Massachusetts, about 70 miles west from where I was, saw the same fireball. I’ll be checking over the next couple of days to see if any other people also file reports, and if so, what we can determine about the true nature of that unexpected evening flash in the sky.
❡ Lots of simple educational opportunities are possible with an event like this. To begin, in your River Houses dictionary and almanac have your students look up the definitions of meteor, meteorite, fireball, and bolide, and look up the major meteor showers that occur every year.
UPDATE: Two other people reported this fireball, and that was enough to determine its location and course: it passed over southwest New Hampshire on a fairly steep trajectory. The AMS has logged and mapped it as Event 4563-2017 — take a look at the map of the object’s path and the observer locations.