RENTREE ATMOSPHERIQUE (975) 15.03.2015

On 15 March 2015 at about 20:45, many people saw a coloured luminous phenomenon cross the sky. GEIPAN received several accounts, including one from a pilot. Observed by hundreds of people in northeastern France and especially Germany and Switzerland, it was clearly a fireball caused by a natural meteoroid entering the atmosphere and fragmenting. The source explains that a fireball results when a “large” object—over 100 g and from a few centimetres to 1 m in diameter—enters the atmosphere, producing a large luminous trail that can illuminate the landscape for several seconds. Several cameras, including those of BOAM, recorded this fireball, enabling its trajectory and thus its natural origin to be determined precisely: a meteoroid, a small rocky body that crossed Earth's orbit. Its initial size was very difficult to determine; the source gives a mass range of 100 g–10 kg. Its relatively shallow trajectory made it visible for almost 10 seconds. It travelled from north-northeast to south-southeast, approximately overhead from Stuttgart to Zurich. GEIPAN received 5 accounts from observers on the ground and 2 from pilots in flight; see the table and maps. One pilot flying north said the phenomenon “grazed” the aircraft, although it was more than 200 km away. GEIPAN describes this illusion of proximity as a constant feature of fireball accounts, including those from pilots. It adds that at high altitude the absence of atmospheric haze makes estimating the distance of an unfamiliar intense light even more impossible. The source recommends an excellent analysis on U-Sphere of all observations of the event compiled by the American Meteor Association. GEIPAN classifies the case A: a fully identified fireball caused by the fall of a natural meteoroid.