Night at the Museum Pt. 2
Sometimes reality exceeds our dreams, and the Museum of Natural History is far larger than any movie set. In the opposite corner from Rose Center for Earth and Space is the Hall of Meteorites. This room has not been placed closer because it can't be moved. The Cape York meteorite fragment here weighs 34 tons! This rock from Space is so heavy that it is mounted on supports descending into bedrock.
Touching a big meteorite is a priceless experience. They are dense because they are made of nickel and iron forged by heat into metal. Sliced sections show the silver-grey texture of steel. Banging on a meteorite with the naked fist produces a ringing sound. Sometime in their past these rocks were exposed to intense heat, forged into a metal that survived the lesser heating of impact. For many centuries, meteorites were humanity's only supply of metals. The Cape York meteorite was mined by local Inuit for steel.
In this room are travellers from the asteroids, Mars and Beyond. the Zagami meteorite (lower photo, top) comes to us from Mars. The Camel Donga meteorite displayed below came from asteroid Vesta. How a tiny body like Vesta could have been so hot was a complete mystery. The lack of olivine in meteorites is another mystery.
The Brenham meteorite was found in a Kansas field. Farmers there in the 1880's often bumped into mysterious metallic rocks. A homesteader named Eliza Kimberly recalled a meteorite she had been shown as a schoolgirl. For five years she collected samples and wrote letters to scientists, despite teasing by her husband and neighbours. (Her work wasn't accepted by the arxiv, either.) Finally a scientist was convinced to examine her meteorites and the woman was proved right. The meteorites she found were billions of years old, dating from a time near Earth's formation.
Elsewhere in the hall is a model of Arizona's Barringer Crater. For many years this hole in the Earth was thought to be a product of volcanoes. A Princeton graduate and lawyer named Daniel Barringer became bored with the office and headed West to be a mining engineer. He tried to take geology at Harvard, but dropped the class when an instructor called his questions "childish." Gaining success in his chosen field, Barringer became obsessively interested in the crater. He spent years and most of his fortune making excavations and trying to convince the science community. Within Barringer's lifetime the world realised he was right too.
There are lessons in this room for all scientists. There have been many times (like today) when the textbooks' explanation for the Universe is lacking. Good ideas can come from outside the mainstream of science, even from a Kansas farm. These ideas may be ignored at first, even ridiculed. Determination and years of work can lead to the truth, even within a lifetime.
The books claim that Earth's nickel-iron core remains hot due to "radioactive decay." We can't get samples of the core, but meteorites like Eliza Kimberly's date from the time of Earth's formation. From their composition and what is known about Earth's density, scientists have concluded that Earth's core is also made of nickel-iron. These meteorites may be considered as samples similiar to the core.
The hypothesis of "radioactive decay" may also be tested here. Earth's core has temperatures exceeding thousands of degrees, hot enough to melt rock. The book claims that isotopes within Earth's core cause it to be hot. Since the Hall of Meteorites contains similiar samples, are any of them about to melt? If they contained even a tiny amount of radioactive isotopes, it would not be safe to go near this room. If they contained any isotopes, those would have decayed to nothing long ago. Today these rocks are cold as the New York Winter, yet Earth's core continues to produce heat.
If Earth's core formed around a singularity, that tiny object would generate heat indefinitely. Today it would have the mass of a small moon and the diameter of a grain of sand, far too tiny to suck us up. The tiny amount of Earth that it eats is far less than the mass that arrives each year via these meteorites. Presence of a singularity would also explain Earth's magnetic field and how Earth formed from dust grains in the first place. Like Eliza Kimberly and Daniel Barringer, a scientist should not be afraid of bold steps.
This week Robot Guy hosts the new Carnival of Space!