Košice

A 2010 fireball over Slovakia caught on security cameras, whose recovered stones were traced back to their orbit in space.

Key facts

Type

Ordinary chondrite (H5)

Fell or found

Fell (witnessed and recorded)

Year

2010 (28 February)

Country

Slovakia

Mass

about 11 kg, in more than 200 fragments

Official name

Košice

Late on the night of 28 February 2010, a bright fireball flashed across the sky over eastern Slovakia, near the city of Košice. Few people were outside to see it, but it was recorded by several security cameras in neighbouring Hungary. Those cameras had not been set up to watch the sky, but they captured the light of the fireball illuminating the ground and buildings, and in some cases the fireball itself. Scientists realised that these recordings could be used to reconstruct its path.

From videos to an orbit

By carefully analysing the videos, researchers worked out the direction, height and speed of the fireball. Combining the measurements, they reconstructed its path through the atmosphere and calculated where fragments might have landed. They also worked out the meteoroid's orbit around the Sun before it collided with Earth. It came from the asteroid belt between Mars and Jupiter. The videos also recorded how the fireball's brightness changed, and sudden flares revealed the moments when the meteoroid broke apart at different heights.

Košice became one of the meteorites with a known orbit, a short and valuable list. Such meteorites are especially important because they link a particular rock in the laboratory with the region of the Solar System it came from.

The search

A team led by scientists from Comenius University in Bratislava, working with colleagues from other countries, searched the predicted fall area in the weeks and months after the fireball. Their efforts were rewarded. They found more than 200 fragments, with a total mass of about 11 kilograms. Most were small, but a few weighed more than a kilogram. Because the search was carefully organised, the team could record exactly where each fragment was found, creating a detailed map of the strewn field.

That map showed how the meteoroid broke up in the atmosphere: small fragments landed at one end of the field and larger ones further along the path, as expected when heavy fragments carry their momentum further.

What it is

Košice is an H5 ordinary chondrite. Ordinary chondrites are the most common meteorites seen to fall. They are made of the minerals olivine and pyroxene, together with grains of iron-nickel metal and iron sulphide. 'H' stands for high iron: H chondrites contain the most metal of the ordinary chondrite groups, which makes them heavy for their size and attracted to a magnet. The number 5 means that the rock was strongly heated in its parent asteroid, so that its chondrules, the small rounded grains typical of chondrites, are less distinct.

Some Košice fragments are breccias, made of different pieces of rock cemented together, showing that its parent body was affected by collisions. Fresh fragments have thin black fusion crusts, and their light grey interiors are speckled with shiny metal grains.

Why it matters

Košice shows how valuable everyday technology can be for science. Security cameras installed for entirely different purposes captured enough information to reconstruct the fall, calculate an orbit and guide a successful search. Today, fireball networks of dedicated cameras continue this work, and many recordings from the public also contribute.

The meteorite is also a model of careful fieldwork. The detailed record of where fragments were found has helped scientists test computer models of how meteoroids break up, slow down and scatter their fragments. That knowledge helps predict where to search after future falls.

If you ever see a bright fireball, report it with as much detail as you can: the time, the direction it travelled, how long it lasted and any sounds you heard. Your report might help scientists find the next meteorite with a known orbit.

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Košice in the catalogue