The search for celestial fossils is this Saturday night | TheUnion.com

The search for celestial fossils is this Saturday night

Al Stahler
Special to The Union

know & go

What: Local astronomers set up scopes to look for ‘fossils’ of the Milky Way, called ‘SkyWatch’

Where: Junction of Highway 49 and old Downieville Highway

When: 8 p.m. Saturday

Diag a hole. Now fill it.

Filling a hole is easy — you don’t need to do a thing. The wind, every now and then, will blow a bit of dirt into the hole. Given enough time, the hole will eventually fill.

We could even harvest some energy as the hole fills. A water wheel spins when water falls over it … we could make a dirt wheel, to spin every time a bit of dirt fell over it.

Given time, that hole will fill until it’s flat-even with the surface. But that’s as high as it’s going to get … the hole will not grow into a pile, because, for every bit of dirt that blows onto the flat spot, another bit will blow off. The only way to build a pile is to carry dirt over and dump it … and that takes energy.

Build a fire, and atoms in the wood — carbon and hydrogen atoms — combine with oxygen, to make CO2 and H2O — carbon dioxide and water. For carbon and hydrogen, combining with oxygen is (sort of) like falling into a hole. The atoms give off energy — heat and light — as they “fall”.

Tiny as they are, atoms have within themselves something even tinier: a nucleus. It’s the nucleus that dictates what kind of atom you’ve got.

Suppose you were to take four hydrogen nuclei, and glue them together. The result would be a new, larger nucleus — a nucleus of a helium atom. For nuclei, gluing themselves together is (sort of) like falling into a hole. Nuclei give off energy when they stick. In the sun, when hydrogens stick together to make helium, they give off sunlight.

Other stars, larger and more massive than our sun, can glue helium nuclei together to make larger nuclei yet — nuclei of carbon and oxygen — and glue these together to make larger nuclei yet: nitrogen and phosphorus, aluminum and iron …

But making iron nuclei is as far as stars can go … the energy hole they’ve been filling is now full … it’s flat. Making larger heavier nuclei — nuclei of the nickel and copper atoms in your pocket change … nuclei of lead … silver … gold … uranium … is like building a pile … it takes energy.

When local astronomers gather to show folks the stars next winter, we’ll focus on a fuzzball in Taurus. Back in 1054, that was no fuzzball, that was an explosion, so bright it could be seen by day. A giant star had exploded: A supernova.

A supernova releases enough energy to slam even heavy atomic nuclei together so hard they stick, building up the nuclei of atoms beyond iron.

And there are yet more energy sources in the universe.

Neutron stars are dead, collapsed stars. A neutron star can be as massive as the sun … but, whereas the sun is close to a million miles across, a neutron star would measure just twenty.

Neutron stars are dense. It’s long been suspected that a collision between neutron stars would be so violent, it would distort space-time – it would send a wave through the universe, like a wave through a pond.

Two years ago this month, observatories in Washington and Louisiana made the first observation of gravitational waves — ripples in space-time … two neutron stars had collided.

More such ripples have since been detected. Turning telescopes toward these collision sites, astronomers see strange glows — colors and temperatures one might expect coming from a region where new atoms were being forged … especially, atoms of gold.

The universe evolves … new atoms are forged, new structures form from those atoms. Looking out into space, astronomers are looking back in time, to see what the universe looked like in the past.

But we don’t need huge telescopes to see fossil evidence of the ancient universe — this Saturday night, at 8 p.m., local astronomers will set up their scopes at the junction of Highway 49 and the old Downieville Highway, to look for nearby remnants — fossils — of the ancient Milky Way — fuzzballs, stars, clusters of stars, that remain from when our galaxy was young. The SkyWatch is free — bring the kids, bring questions, bring your imagination.

And bring a sweater.

Al Stahler enjoys sharing nature with friends and neighbors. His science stories can be heard on KVMR-FM (89.5 MHz), and he may be reached at stahler@kvmr.org.


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