Scientists seek meteorite footage

Scientists are requesting public reports of last night’s spectacular green fireball, caused by a meteor entering the Earth’s atmosphere.

The meteor’s sonic boom was heard across South Canterbury. Seen at 8:06pm on Thursday night, it was reported on social media by people from across the South Island. The arrival was caught by at least four specialised fireball detection cameras, as well as on CCTV and by at least one lucky astrophotographer.

This is New Zealand’s second notable fireball this month. On July 7, a meteor exploded in daylight near Wellington with a force equivalent to 1,800 tonnes of TNT creating a sonic boom heard across New Zealand. Two weeks on, Canterbury experienced its own unrelated fireball.

While last night’s event has been widely reported on social media, the scientific collaboration Fireballs Aotearoa is keen to get official reports from observers entered into fireballs.nz/report. These observations can help determine where any potential meteorite may have fallen. Only five reports had been received by 2pm July 22, and many more will be needed to get enough information to calculate the path of the fireball.

Dr Michele Bannister, of the University of Canterbury, says anyone finding a potential meteorite should check for a distinctive black surface from the meteor melting during its passage through the atmosphere.

“Please photograph it in place: note the location using your phone GPS, and avoid touching it with your bare hands (the less contamination the better). Pick it up in fresh aluminium foil if possible, or otherwise a new clean plastic bag. And let us know! “

Fireballs Aotearoa meteorite analysis lead scientist Dr James Scott of Otago University says last night’s meteor fragmented towards the end of its flight.

“Most of the meteoroid vaporised during the six or so seconds of visible flight. However, with this one, it’s possible fragments may have reached ground level somewhere in the central South Island.”

“At this point we cannot be precise in calculating where any pieces might have landed, without further information from eyewitnesses.”

Jeremy Taylor of Fireballs Aotearoa says the more video footage and the more observer reports they receive will improve the accuracy of their measurements.

“Ideally we need multiple videos, with the exact time and the location to within 10m, that capture the meteor along with some visible stars.”

Fireballs Aotearoa has more than 30 cameras in New Zealand continually monitoring the night sky for meteors and fireballs. The July 21 meteor was captured by both a GMN-RMS camera in Timaru, and by the three CAMS meteor network stations run by the University of Canterbury, NASA and SETI Institute in Christchurch, Ashburton and Takapō. Unlike the July 7 Wellington meteor, the meteor seen over Canterbury was too small to be detected as an atmospheric explosion, nor was it detected by MetService radar.

If any meteorite is found from the July 21 fireball, this would be Canterbury’s first meteorite recovered in over 50 years.

Meteorites are made of the same materials that formed into Earth and the other planets. Most come from asteroids, and more rarely from bits blasted off the Moon or Mars by impacts. An asteroid or a meteoroid is a small piece of rock in space near the orbit of Earth. A meteor or fireball happens when a meteoroid hits the Earth’s atmosphere, which makes it slow down suddenly and heat up. A meteorite is the rock found on the ground if a meteor manages to survive its travel through the atmosphere.