Fireballs Aotearoa Press Release. For Immediate Release
22nd July 2022
Last night’s fireball over Canterbury may have dropped a meteorite
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, from Dunedin to Nelson. The arrival was caught by at least four specialised fireball detection cameras, as well as on CCTV and by at least one lucky astrophotographer[i].
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 from both Islands. 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/ , because these observations can be used to help determine where any potential meteorite may have fallen. Only five reports had been received by 2:00pm July 22, and many more will be needed to get enough information to calculate the path of the fireball.
Fireballs Aotearoa’s meteorite analysis lead scientist, Dr James Scott of Otago University said “This meteor fragmented towards the end of its flight, as you can see in the CCTV video from Moana[ii]. Most of the meteoroid vaporised during the six or so seconds of visible flight. However, with this one it is possible fragments may have reached ground level somewhere in the central South Island”.
He continued “At this point we cannot be precise in calculating where any pieces might have landed, without further information from eyewitnesses.”
Data from Fireballs Aotearoa’s specialised meteor detection cameras, supplemented with the observer reports, will be used to create a map of possible fall locations, which will be updated as new data refines the computer model.
Jeremy Taylor of Fireballs Aotearoa said “The more video footage and the more observer reports we get, the better we can improve the accuracy of our measurements of the meteor through the atmosphere, and reduce the number of hectares of the predicted fall zone.”
“Ideally we need multiple videos, with the exact time and the location to within 10m, that capture the meteor along with some visible stars.”
Collaboration scientific co-lead Dr Michele Bannister of the University of Canterbury said “The green colour reported is common in large, high-speed meteors and is caused by extreme heating of atmospheric oxygen by the meteor’s shock wave. The videos suggest it was probably too fast for it to be reentering space debris.”
She provided this advice for anyone finding a potential meteorite: “They’ll have a distinct black surface from 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 has more than thirty cameras in NZ 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.
Jeremy Taylor says that it has been estimated that more than 40 tonnes of extra-terrestrial material enters Earth’s atmosphere each year. He said “Most are sand-sized particles known as cosmic dust. Even over a relatively small land area like New Zealand, about twenty larger meteorites land each year, most barely the size of a sugar cube.”
“However, two or three will be bigger — and that might be the case with this one. Every few years a much bigger one will arrive, like the 1.3kg one that crashed through the roof of a home in Ellerslie back on 12 June 2004. Detecting freshly fallen meteorites is our best chance to recover them for study.”
If any meteorite is found from the July 21 fireball, this would be Canterbury’s first meteorite recovered in over fifty years. A primitive chondrite was recovered from Morven in 1925 and an iron meteorite was found near View Hill in 1953.
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.
Fireballs Aotearoa was formed in February 2022 to recover freshly-fallen meteorites in New Zealand. It is a collaboration between New Zealand’s meteor camera networks and scientists at the Universities of Canterbury and Otago. At present the limited extent of the network means the likely path of this meteor has fallen into a gap in the coverage, limiting the data from this event. The network is keen for people interested in citizen science to help improve the sky coverage. Anyone can participate in this initiative; setting up a specialised meteor monitoring camera costs as little as $400. More information is at fireballs.nz.
Fireballs Aotearoa asked people not to trespass while looking for any meteorites. “If you find a piece on your land or on a road, please let us know. But don’t go hunting for it: there’s a lot of bush that this may have fallen in.”
If you have a photo or video of a meteor please go to https://fireballs.nz/report/ to upload and share it.
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Footnotes: external resources, not provided by Fireballs Aotearoa
[i] Greg Price, Richmond – Hi-res still images https://www.facebook.com/groups/5889909863/permalink/10159278464949864
[ii] Moana – CCTV showing fragmentation: https://twitter.com/kiwijezza/status/1550067957984022528