A meteor that crashed into farmland just east of Dargaville late last year could still be found and will likely make for a remarkable discovery - due to its unusually large size, an expert claims.
Dr James Scott, associate professor of geology at the University of Otago, said: “We now estimate that the meteoritic material that survived the fireball stage was a remarkable 10kg in size. However, the modelling requires assumptions and the mass could’ve been as large as 60kg.”
If the meteorite were to be as big as 60kg and found this would make it the largest to have been discovered in New Zealand.
The largest so far was the 50kg “Dunganville”, discovered in a Westland creek bed in 1976.
“It may be large, but it may also have been fragmented into smaller bits. The mass of the rock that came in was evidently significant though, even if it did fragment.”
The meteor was seen as a huge fireball over Northland skies on November 19 last year and was so bright that it was seen from Kaitāia to Rotorua.
Scott said it flashed across the earth’s atmosphere, initially travelling about 15 km/h, as the air in front of it was compressed and heated. The heat caused the meteoroid margins to begin to melt and components to vaporise, causing the several-second-long bright fireball seen across the night sky.
“It was visible from an elevation of 64km down to 16km. The meteoroid was travelling faster than the speed of sound and several sonic booms rang out as people were passed by the radiating shock wave cone.”
Video footage from rural properties between Whangārei and Dargaville appears to show night turning into day as the meteor flew past.
Witness Sarah Ivicevich, who was driving at the time, said: “The fireball, it was huge, way bigger than a satellite or shooting star, like 1000 times bigger than a shooting star. The fireball was low in the sky, quite slow-moving, with an orange front and a white/light yellow/white tail,”
Trish Nairn of Pakotai said at the time: “After the flash lighting up my paddock, there was a huge, quick boom which shook my house.”
Scott said researchers had now gathered enough information to be able to triangulate where the meteor most likely landed.
“We managed to get more video footage, which enabled the properties of the fireball to be characterised. So with extra security camera footage, some additional images, and wind data, Fireballs Aotearoa and colleagues in the Global Meteor Network have triangulated the Northland meteorite to have landed in Pukehuia.”
Pukehuia is 30km east of Dargaville and near the Tangihua Range.
However, he does not advocate that locals search for the missing meteorite without farmers’ permission.
For those interested in searching, permission must be granted from the land owners. More information can be found at fireballs.nz.
A search party had been planned earlier in the year to cover the potential strew field but Cyclone Gabrielle stymied that.
“The search was about to go out but was curtailed a couple of days beforehand by the flooding.”
There are no further plans to take a search party into the area any time soon.
“If people were to go ...it would be important to look for black rocks with thin, glassy rinds that look out of place.
“Any recent meteorite should stand out because it has a black fusion crust. This is actually the glass that coated the rock following the hot fireball stage - that is commonly partially sculpted with flow lines resulting from the high-speed travel.”
If the meteorite surface was damaged during landing, this black rind, which is only 1-2 mm thick, will typically reveal a quite different coloured interior.
“Metal detectors could well be useful, but of course pick up anything metallic, and there would be plenty of that in farmland. Given the upper limit of the size, big fragments would likely be at least partially embedded in the ground. Small particles, which are common, should lie on the surface – even after nearly a year,” Scott said.
“If it were found, it would be New Zealand’s 10th confirmed meteorite in 160 years. Only two of the nine known were seen to “fall”; the rest were discovered long after they reached New Zealand’s surface.”
Should anyone find a rock they suspect to be a meteorite, first photograph it, record the location, carefully place it in a plastic bag, and make immediate contact with Fireballs Aotearoa.
“Avoid directly handling it because this material can contain delicate acids that some scientists think may be the building blocks of life.”
But for those keen to search because they think it might be worth something, Scott says think again. It isn’t actually worth much, he says.
“Rules are that it belongs to the land owner, but also that they can’t sell it overseas without permission from the Government, who won’t give it.
“If it’s on public land, then it’s whoever finds it. In any case, what one is worth is dependent on knowing what type it is, and that requires scientific appraisal, and size.
“It’d be better to get the prize of being the one having found it and donating it to a museum. Scientists would get much more out of it than having it sit on someone’s window sill.”
Occasionally Earth is rocked by really big meteorites such as the one estimated at 10km in diameter that struck the Yucatan Peninsula about 65 million years ago and resulted in the global extinction of most dinosaurs.
The last NZ meteorite to be discovered was a 1.3kg rock that fell through a roof in the Auckland suburb of Ellerslie in 2003. It is now in the Auckland War Memorial Museum.