Wednesday 30 October 2019

Fireball meteor over southern Ireland.

Witnesses across Britain and Ireland have reported witnessing a fireball meteor slightly before 8.00 pm local time (slightly  before 7.00 pm GMT) on Monday 28 October 2019. The majority of sightings came from Ireland, but with many sightings In Wales, Scotland and northern England. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry. On this occasion many reports stated that the meteor was green, suggesting that the meteor had a high magnesium or nickel content, and moving southeast to northwest, first entering the atmosphere over the Celtic Sea and disappearing somewhere over County Cork.

Fireball meteor seen from outside Banteer in County Cork on 28 October 2019. Sean Linehan/Irish Independent.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as an luminous object. However this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).
 Map showing areas where sightings of the meteor were reported, and the apparent path of the object (blue arrow). American Meteor Society.
These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.
See also...
Follow Sciency Thoughts on Facebook.