New Zealand’s 11th Confirmed Meteorite Recovered From Wairarapa

On the 28th of August, at 10.26 pm, a
rock from space shot across Earth’s atmosphere over the
lower North Island. The associated fireball was seen and
reported widely, with many in the Kapiti to Masterton region
describing the amazing sight. One anonymous person in
Feilding writing on the fireball report page that the
“Sky lit up like a bonfire in flames.”

A
sonic boom was heard shortly afterwards by people on the
Kapiti Coast and around Western Wairarapa. One person from
East Taratahi reported ”It consisted of multiple
crackles, several distinct booms, and prolonged rolling
rumbling, giving the impression of an object travelling
through the atmosphere and fragmenting repeatedly”,
which is exactly what happened. Since the soundwaves travel
slower than light, these arrived shortly after the
fireball.

The trajectory of the
fireball was calculated by Fireballs
Aotearoa using meteor cameras that are distributed
across New Zealand as part of a large citizen science
project (www.fireballs.nz) aimed
at recovering meteorites and documenting meteor showers
above New Zealand.

“The camera data showed to us
that the meteor was first visible in Earth’s atmosphere at
90 km, where it was travelling at a rapid
14 km/s. This speed represents what it has
been travelling at for millions of years around the Sun.
However, as it reached to 30 km above the
Earth, it began to rapidly decelerate, and by 18 km
it was travelling at “only” 2
km/s. Through this phase, the air in front of the
meteorite was compressed and heated up, causing the outside
of the rock to melt. This gave the bright fireball trail
seen across the night sky” said Steve Wyn-Harris,
Director of Fireballs Aotearoa.

“During the
fireball stage, small meteors generally
lose between 90 and 100% of their mass. Shooting stars, for
example, are typically only pea-sized and burn up
completely. However, if a meteor has a steep entry, or
started out as a mass of more than about 10 kg, some
portions may survive the transit through the atmosphere. The
rocks that land on the ground are called
meteorites. The 813 gm Takapō Meteorite
found by Fireballs Aotearoa in March 2024 started out at the
top of the atmosphere at approximately 14 kg” said Dr.
Marshall Palmer of Fireballs Aotearoa.

In the last
stages of the fireball, the meteor cameras imaged several
fragmentation events of the rock, indicating the possibility
of many fragments on the ground. This occurred because the
forces on either side of the meteorite were so unequal that
the rock ripped itself apart. Just 7
seconds after it appeared, the rock had slowed so that the
air was no longer sufficiently hot enough to cause
melting.

“The material that survived the fireball
stage then fell to the ground during a stage that is known
as dark flight. The meteorites are
distributed across a strewn-field, which is
the approximate area that the meteoritic material is
“strewn” about. With scientists from Canada and
Scotland, we used the wind speeds and predicted masses and
shapes of surviving material, to determine where the
strewnfield may be.

“Meteorite fragments that
land usually have black crust, which is known as a fusion
crust. This crust is actually a glass from when the outside
of the meteorite was molten. This fusion crust is very thin
(<1-2 mm) and gives the rock a smooth black surface on
all sides. If the interior under the fusion crust can be
observed, which can happen when the meteorite hits the
ground, it is usually a completely different colour because
it still exposes the original rock. The colour depends on
the type of meteorite, but it is most commonly very pale
with flecks of iron-rich minerals that give many meteorites
the ability to attract a magnet” said Professor James
Scott, of Fireballs Aotearoa.

Recognising the
possibility of a meteorite on the ground, Fireballs Aotearoa
organized a search of the predicted strewn-field. After
several days of searching, four small fusion encrusted
fragments were discovered, weighing 8, 9,12 and 40 grams.
There were no craters because the impact of very small
meteorites is really more of a small bump as they “fall”
at terminal velocity.

“The trajectory that the
rock followed prior to entering the atmosphere indicates
that that it was derived from the Asteroid Belt. The rock is
therefore certainly from the start of the Solar System and
almost 4.6 billion years old. We are lucky that after such a
long duration it landed in New Zealand, and now will be
formally classified by Marshall Palmer as soon as possible,
given an official name and will become New Zealand’s 11th
documented meteorite.

“Should people find
black rocks in the area surrounding Masterton that they
suspect could be a meteorite, they should photograph the
rock and location, carefully bag the sample and contact
FireballsAotearoa@gmail.com
to confirm its origin. Please respect landowners
rights” said Steve Wyn-Harris.

Fireballs
Aotearoa is a non-profit section of the Royal
Astronomical Society of New Zealand. Our goals are to
provide information about meteors above New Zealand to the
public and recover New Zealand meteorites and donate them to
museums where they can be observed by the public and
accessed for scientific analysis. Fireballs Aotearoa
successful observed and recovered the Takapō meteorite in
2024 (on display in Tuhua/Otago Museum) and has contributed
to documenting 37 different meteor showers including
discovering new ones. The project has been supported by the
Perpetual Guardian Fund and Curious Minds administered by
Otago Museum and several anonymous
doners.

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