A chunk of the Murchison meteorite at the Smithsonian's National Museum of Natural History. (Basilicofresco via Wikicommons under CC BY-SA 3.0)
Smithsonian Magazine has an article about some very old dust. Even if you haven't cleaned lately, it's highly doubtful the dust around your home is as old as the dust described in a recent paper published in the journal PNAS. The lead author is a curator of meteorites at the Field Museum in Chicago, which has a large collection of meteorites. The meteorite analyzed in this study is the famous Murchison meteorite.
A little more than 50 years ago, on September 28, 1969, a meteorite crashed near the rural village of Murchison in Victoria, Australia. Witnesses saw a fireball streak through the sky and break into three pieces just before 11 a.m. local time, followed by an audible tremor in the area. Locals came upon several fragments of the meteorite, the largest of which, with a mass of 680 grams, crashed through a roof and landed in a pile of hay. All together, some 100 kilograms of the Murchison meteorite were recovered and sent to scientific institutions around the world.
“The Murchison meteorite is a wonderful resource for the scientific community,” says Philipp Heck, a curator of meteorites at the Field Museum in Chicago, which houses a large portion of the extraterrestrial object. “It contains some of the oldest condensates in the solar system and also presolar materials.”
Some of those presolar materials—microscopic grains that formed before the sun, measuring about 2 to 30 micrometers across—have been dated at 4.6 to 4.9 billion years old. And one of the grains analyzed in a study published today in the Proceedings of the National Academy of Sciences is estimated to be roughly 7 billion years old, making it the oldest known material on Earth.
“The oldest one is about 3 billion years older than the sun, [which] makes it about 7 [or 7.5] billion years old,” says Heck, the lead author of the study. The sun formed about 4.6 billion years ago, and Earth formed about 4.54 billion years ago.
