Great Balls of Fire: Fireballs in the Night Sky

On Sunday night, Hundreds of people across the British Isles reported seeing a large fireball blazing across the night sky then exploding in a bright flash, that was followed by a shower of brightly lit orange fragments falling to earth. The fireball was seen just before 10pm as it blazed its trail through the atmosphere for around six seconds.The UK Meteor Network, an amateur group of astronomy enthusiasts that meticulously logs meteor and fireball sightings, said it had received over 120 reports of the exploding fireball.In years gone by, fireballs, meteors and comets have fired up the public imagination, in Roman and medieval times, the arrival of a blazing fireball in the night sky was seen as a portent either of an imminent disaster or as the herald of a new age.

So what exactly is a fireball?

A fireball is a very bright meteor also known as a falling or shooting star. It’s the visible passage, the light streak, of a glowing meteoroid or asteroid that crashes through the Earth’s atmosphere. After a meteoriod hits the atmosphere, its heated to bright incandescence by friction with air molecules in the Earth’s upper atmosphere. This creates the streak of light.Generally, a fireball is brighter than magnitude -4, which is about the same magnitude as Venus as seen in the night sky. Meteoroids, also known as meteorites, range in size from metre-wide pieces of rock to small dust particles moving through space that have managed to escape the gravitational pull of other planets.Most are fragments of asteroids from the Asteroid Belt between the orbits of Jupiter and Mars. Others are from comets that orbit the sun. Asteroids, space rocks larger than a metre wide, explode into the atmosphere, creating huge fireballs, and are potentially cataclysmic events.The fireball seen on Sunday night, is technically known as a bolide, a type of fireball which explodes in a bright flash at its end, often with visible glowing fragments falling to earth. Researchers believe that on Sunday most of the fireball vapourised during the six seconds of its visible flight. But it’s thought that some fragments reached the ground, falling just north of Cheltenham, on farm land, in the Cotswolds, between Winchcombe and Stow-on-the-Wold.

Don’t pick up fallen fragments of the fireball

Scientists have warned the public not to touch these fragments, if they find them. To avoid any contamination, that might affect the analysis of these objects, take note of their position and photograph them in place.If you happen to see another fireball fall to earth, at any time, remember to report all the details to the skywatchers at the UK Meteor Network, the UK Fireball Network or the UK Fireball Alliance who are very keen to log such events.All of these groups attempt to recover UK meteorite falls, and these meteorites can often reveal vital information regarding how the solar system formed, and the orbits of these falling rocks can determine from which asteroid or asteroid families they originated.