Over the last few weeks there has been some headlines about a rare event known as a fireball. These are truly spectacular occurences that provoke amazement, confusion, and sometimes even fear. But what exactly is a fireball?Many of us will have witnessed meteors, or shooting stars, at some point in our lives. Meteors are bits of debris and dust – about the size of a grain of rice – left over from comets in space that have entered Earth’s atmosphere. Friction causes them to heat up and make the air around them glow brightly. What we see is a fast-moving streak of light in the sky. A fireball is just like a meteor, except caused by bigger debris, anything from golfball-sized to the size of a car, or bigger! When these burn up in the atmosphere, they glow extremelybrightly, sometimes bright enough to cast shadows, and certainly bright enough to see from the city. As a guideline, if a fireball appears brighter than a full moon it means that it may be big enough to survive the fall to the ground. When fragments arrive on Earth’s surface they’re known as meteorites.
Don’t be fooled, though; while they look like they’re very close, in reality they are 70-100km above the ground. While it’s easy to think that something may have fallen nearby, remember that hundreds of other people all over the country have seen the same thing!
Astronomy Ireland gathers information on fireball sightings to determine if anything may have landed on the surface. If you do ever see a fireball, visitwww.astronomy.ie/fireball to fill out a short report form, so that your sighting can be checked against others. If something does ever land, Astronomy Ireland will attempt to work out the general location of the fall site, allowing people to look for the valuable space rocks!