ost of the time, people imagine the Earth as basically self-contained. It's a discrete planet, orbiting around the sun along with the other planets in an ordered system. But the more astronomers look to the skies, the more we learn about the enormous quantity and variety of space junk that shares this space with us -- and collisions are an unavoidable conclusion.
Pluto was demoted from planet to dwarf planet because scientists started noticing a lot of space rocks that looked more like pluto than Earth or Jupiter -- there may be dozens or even hundreds of similar dwarf planets out there, waiting to be found. On top of that, there are half a million known asteroids, mostly located in the belt between Mars and Jupiter. Scientists have identified 4,000 comets, but there could be a hundred billion more, hiding unseen in the Oort cloud.
The history of Earth is the history of collisions. Scientists suspect that all of the water on Earth may have traveled here by asteroid or comet, since in its early history the planet would have been too hot, with an atmosphere too thin, to contain H2O. Today we see evidence of space junk in regular meteor showers -- pieces of stardust set on fire in a violent collision with the atmosphere.
Most of those meteors will break apart on entry, dissolving into dust. Scientists estimate that 10-40 tons of stardust enter our atmosphere each day. On rare occasions, a space rock will be big enough to withstand the force of entry, and will fall to Earth as a meteorite. And because they are extraordinary, and because they are beautiful, and because they remind us of our small place in this vast, chaotic universe, we prize these space rocks dearly. We hunt them, we buy them, we study them, we preserve them in glass cases, and we put them on pedestals.
Later this month, dozens of rare and unique meteorites will be auctioned at Christie's in London. "These items are extraordinarily beautiful, and seeing them in person is really a wonderful chance," auction specialist James Hyslop tells Inverse. He has spent several months collecting the most impressive and valuable pieces of space rock on this planet.
The meteorites represent an extraordinary diversity of shapes, sizes, colors, and stories. Many are of great scientific importance. The Allende, for example, fell to Earth in 1969 and contains material inside it that is older than the solar system itself. A half-pound block of that meteorite is up for auction, with an estimated value of $3,100 to $4,500.
Some of the meteorites have came from the moon, or from Mars. We know this because of chemical signatures that match these rocks to specimens collected on space missions. "Less than one in 500 meteorites have been confirmed to originate from the moon," says Hyslop. "What I love about the lunar meteorites is that it's kind of two meteorites for the price of one, because for a piece of the moon to get here on Earth millions of years ago, there must have been an impact event on the surface of the moon to knock a bit of it out into space, where millions of years later it would cross with Earth's orbit and then fall down."
Also in the collection is the only meteorite documented to have caused a death. In 1972 a Venezuelan farmer and physician came upon his cow, dead by blow to the neck, with a strange rock next to the carcass. Although he suspected what had happened, he did realize what a rare event he had witnessed. He ate the cow, and used the meteorite as a doorstop. Years later scientists confirmed the extraterrestrial origins of the rock, and he was informed of the uniqueness of his meteorite's story. The rock is expected to sell at between $6,100 and $9,000.
The most valuable rock in the auction is a behemoth 1,433-pound meteorite, discovered in 2005 in Kansas. Most meteors tumble through the atmosphere as they fall to Earth, but this one shot down in a singular direction, giving it a dramatic domed shape.
According to the sale catalogue:
The parabolic "heat shield" curvature seen here was sculpted at exceedingly high temperatures, and is the most efficient angle at which heat defects from a falling object. This is the reason NASA engineers studied this parabola in other oriented meteorites when designing the heat shields for the first manned space capsules. The smoothness of the surface is the result of the melting process in Earth's upper atmosphere in which olivine crystals melted and exposed tendrils of the nickel-iron matrix in a process that repeated until the meteorite slowed to terminal velocity. A significant fraction of the meteorite vaporized or ablated off its edges during its descent. The ablative heat shield-like action pushed the hottest gases (referred to as the shock layer -- which is hotter than the surface of the sun -- away from the meteorite).
While there is uncertainty regarding whether any Native Americans witnessed the Brenham meteorite shower, petroglyphs have been found nearby depicting what could have been the Brenham event. The presence of Brenham meteorites in numerous burial mounds as far away as Ohio -- including jewellery fashioned out of Brenham meteorites -- indicates that Native Americans, like modern collectors, were transfixed by the beautiful extraterrestrial stones.
All of the space rocks in the auction will be available for public viewing in London April 16-19, before the sale itself on April 20th.
If you don't have a million dollars, or even a few thousand, to drop on a rare meteorite, there's no need to give up on your dreams of owning your very own piece of space junk. The various marketplaces of the internet will sell small meteorites for prices as low as $0.50 a gram. There's also a thriving market for affordable meteorite jewelry, in case you want to take your stardust with you wherever you go. Or you could go hunting yourself. Many meteorites are discovered in the desert, where black stones stick out against the white sand.
"In the last three or four years, we've really noticed that demand for them has been going up and up and up," he says. "It really is a wonderful experience to have a piece of another planet on the palm of your hand."
Photos via Christie's