Tagish Lake

A fragile carbon-rich meteorite that fell onto a frozen Canadian lake in 2000 and was collected without being touched by bare hands.

Key facts

Type

Carbonaceous chondrite (ungrouped, type 2)

Fell or found

Fell (witnessed)

Year

2000 (18 January)

Country

Canada (British Columbia)

Mass

about 10 kg recovered

Official name

Tagish Lake

On the morning of 18 January 2000, a dazzling fireball blazed across the sky of north-western Canada, seen from the Yukon and British Columbia and even detected by satellites in orbit. It exploded high in the atmosphere, and small black fragments rained down onto the frozen Taku Arm of Tagish Lake in northern British Columbia.

A careful collector

A week later, a local resident named Jim Brook was driving across the frozen lake when he noticed dark stones lying on the ice. Remembering the fireball, he realised what they might be. Crucially, he collected dozens of them without touching them with his bare hands, picking them up in clean plastic bags. He kept them frozen, first outdoors and then in a freezer, until scientists could take charge of them. Those first pieces, weighing roughly 850 grams in total, became some of the most pristine meteorite samples ever recovered.

In the spring, more fragments were recovered by a team of scientists and volunteers from the melting ice and snow, some of them soaked by water. Altogether, around 10 kilograms were collected. Satellite data, eyewitness accounts and video were combined to reconstruct the fireball's path, which helped to guide the spring search. Because the meteoroid broke up so dramatically, scientists estimate that the object entering the atmosphere had been several metres across and weighed tens of tonnes, of which only a tiny fraction survived.

An unusual meteorite

Tagish Lake is a carbonaceous chondrite, a type of stony meteorite rich in carbon and water-bearing minerals. It does not fit neatly into any of the established groups, so it is classed as ungrouped. It is very dark, extremely porous and crumbly, with a low density, and it is rich in carbonate minerals and clays formed by water inside its parent body. It contains a wide range of organic compounds, including amino acids, and tiny hollow organic spheres called nanoglobules, as well as presolar grains, specks of dust older than the Sun.

Different fragments show different degrees of alteration by water, which suggests that its parent body was a jumble of material with a complicated history.

A fragment of a dark asteroid

Because many people saw the fireball and it was recorded by instruments, scientists could calculate its orbit, which came from the asteroid belt. The meteorite's colour and the way it reflects light resemble some of the darkest asteroids in the outer Solar System, known as D-type asteroids. Many scientists think Tagish Lake may be a sample of one of these primitive bodies, which have rarely, if ever, been sampled by other meteorites.

Kept in the cold

The frozen pieces collected by Jim Brook have been stored at sub-zero temperatures and handled with special care, allowing scientists to study volatile organic compounds that would otherwise have escaped or changed. They have been especially valuable for research on how complex organic molecules and water were delivered to the early Earth. Much of the material is held by institutions in Canada, including the Royal Ontario Museum and the University of Alberta.

Why it matters

Tagish Lake is one of the most primitive and organic-rich meteorites known, and it was collected in an almost ideal way. More than two decades after its fall, it is still being studied with new techniques. It shows the value of a calm, careful finder who keeps a fresh meteorite clean and cold and gets it to scientists quickly. If you ever find what you think is a fresh meteorite, take a leaf from Jim Brook's book: don't touch it with bare hands, put it in a clean bag or foil, note exactly where you found it, and contact a museum or university.

Did you know?

See more

Tagish Lake in the catalogue