Valda is a UK photographer specializing in intentional camera movement (ICM) and multiple exposure work, which she often combines as part of her workflow. “They show us the very building blocks of our solar system when it started.This week on the podcast I had a wonderful conversation with Valda Bailey. “They’re time capsules from billions of years ago,” says Corrigan. If an asteroid collision results in broken pieces being shot off their trajectory and into Earth’s gravitational pull and onto its surface, they are delivering a unique opportunity.
It’s not as simple as rocks banging into each other―it takes a lot of pressure to turn carbon into diamonds!”īecause asteroids in the asteroid belt never formed into planets, they are very primitive (and valuable) resources for scientists. “They help us understand what type of materials are out there in the asteroid belt and the kind of activity happening. “There is a lot of information in ureilites,” Corrigan says. In addition to hinting at what may have been happening on Earth billions of years ago, ureilites have a much bigger story that they help tell. The shattered appearance reflects how the asteroid smashed from an impact, the heat from which caused the crystals to fuse back together with the carbon filling in the spaces in between. The colors revealed by the polarized light are influenced by the different levels of magnesium and iron in the olivine and pyroxene crystals. Bright blues, yellows, magentas and greens appear, each separated by a busy network of the black graphite and diamonds―all looking like an avant-garde stained glass window. (Photo by Johnny Gibbons)īut when Corrigan hits it with polarized light, the ureilite transforms. It began as part of an asteroid before breaking off due to a collision and making its way to Earth.
This 4.5-billion-year-old ureilite meteorite is one of the oldest objects in the Smithsonian’s collection. Things look pretty routine so far―the specimen is kind of dark with some clear-ish crystals, like one would expect from a rock. To look back 4.5 billion years through a ureilite lens, Corrigan takes a slice from a meteorite 30 microns thick (about the width of a human hair) and puts it under a petrographic microscope.
These ureilites allow us to study our planet’s geological history in way that would otherwise be impossible,” she adds. “And because olivine, pyroxene, and carbon also occur here, it’s probable that the same process was happening when meteorites were smacking into Earth. “When these asteroids collided, which happened a lot during the early parts of our solar system’s history, we think a shockwave was sent through them with pressure so great that it transformed their carbon into graphite and diamonds.
Smithsonian geologist Cari Corrigan uses a petrographic microscope to examine ureilites and look back 4.5 billion years. No, they were knocking, bumping and smashing into each other in the asteroid belt between Mars and Jupiter, and that’s when something really cool happened. Ureilites, however, weren’t just calmly floating around in space until they one day made their way to Earth. Ureilites are made up of olivine and pyroxene (elements containing different levels of magnesium and iron), and carbon―all things also found on Earth. To get a better picture of how Earth’s nascent rocky surface reacted each time it was hit, Corrigan turns to a 4.5 billion-year-old kaleidoscope of elements known as a ureilite (YUR-a-lite) meteorite. What was happening (geologically speaking) on Earth way back when it was a mere babe and being showered with meteorites? Until a time machine is invented, it might be hard to tell….that is, unless you’re Cari Corrigan, geologist at the Smithsonian’s National Museum of Natural History. When examined under a microscope with polarized light, ureilite meteorites appear in dazzling colors separated by black bands of graphite and space diamonds.
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