Where do babies (and everything else) come from?
Special to The Union
A newborn babe weighs just a few pounds; some years later, quite a bit more. The weight comes from the gazillions of atoms she’s added to her body — atoms that came from her food.
Tiny carrot seeds become full-grown carrots by adding gazillions of new atoms to their carrot bodies — atoms that came from soil, water, and air … from the Earth.
The Milky Way glows high in the summer sky, the combined light of billions of far-away stars. Here and there, the glow is interrupted by dark rifts — huge clouds of dust that block the stars’ light.
Hanging from the constellation Orion’s belt is a dagger. Binoculars reveal the middle “star” of the dagger to be a glowing cloud of gas and dust.
Denser than the dust clouds of the Milky Way, the cloud is collapsing to form baby stars.
From such a cloud of gas and dust, four-and-a-half billion years ago, our solar system condensed.
From the gas and dust came the atoms that formed sun and Earth, soil and water and air, our food, our bodies.
The atoms in our bodies were once in dust and gas that floated among the stars — the interstellar medium — stardust.
The spacecraft Stardust launched in 2002, to sample a comet, to see what comets are made of.
En route, Stardust also collected samples of interstellar dust that had drifted into the solar system.
To capture the dust, Stardust deployed sheets of aluminum foil. Crashing into the foil at thousands of miles an hour, the dust blasted tiny craters. Analyzing the atoms in the craters revealed the composition of the dust.
The collision left atoms, but destroyed the particle of dust, and the information that could be gleaned from its structure, from the way it was put together.
The first American satellite to reach space, in 1958, discovered that space is radioactive.
Subatomic particles (“cosmic rays”) slam into everything out there.
Intense radiation breaks the bonds that hold one atom to another, and so it destroys life.
By breaking the bonds between atoms, intense radiation also destroys crystals, busting up their orderly arrangement, reducing them to random disorder.
Exposed to intense radiation, space dust was expected to be amorphous — non-crystalline.
Confirming that would require capturing intact bits of dust. Which would require a material that was solid, yet yielding.
A chunk of aerogel weighs only a bit more than the air around it. Holding a cube of the material is like holding a brick made of wispy blue smoke.
Turning the cube until the light strikes it from just the right angle, it disappears. Aerogel is an excellent material for catching space dust.
I spoke recently with Andrew Westphal (University of California, Berkeley), principal investigator for the Stardust mission.
In a paper published earlier this month in “Science,” he and his colleagues describe seven particles (actually, three particles and four craters created by particles) that they believe are dust from between the stars. It came in from the right direction (relative to how Earth moves though space); the next step will be an atom-by-atom analysis, to see if the a mix of atoms is sufficiently odd to have come from out of this solar system. Surprisingly, two of the dust motes were crystalline. The next step for the team will be to convince themselves that the mix of atoms in the dust is truly alien.
In the pre-dawn sky, Saturday morning:
Venus orbits the sun closer – and therefore faster – than we. Heading for the far side of the sun, Venus is now low in the east, before dawn.
Earth orbits the sun closer and faster than Jupiter. We are catching up with Jupiter, which will put it high in the nighttime sky this winter. For now, Jupiter is just a bit above Venus in the pre-dawn eastern sky.
Near both planets, this Saturday before dawn, will hang the thin-crescent moon.
Al Stahler’s science programs can be heard on alternate Tuesdays at noon on KVMR-FM (89.5 MHz). He teaches students of all ages, visits classrooms, and may be reached at firstname.lastname@example.org
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