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Monday, February 16, 2009

Discoveries

A Gamma Ray Blast from the Past

A long time ago, in a galaxy far, far away, a great explosion took place. This week, astronomers say they saw it--from nearly 13 billion light-years away. Called GRB 050904, it's the most distant explosion ever detected.

Astronomers spotted the explosion, a 200-second gamma ray burst (GRB), thanks largely to NASA's Swift satellite, which was designed to detect GRBs. After noticing the burst, the Swift sent a message to ground-based scientists, saying, in effect, "Hey, lookee here!" When they did, they caught a glimpse of light that left its source nearly 13 billion years ago. That's less than a billion years after the Big Bang itself, according to current astronomical theory.

Scientists are only now starting to understand gamma ray bursts (GRBs), which were first detected in the late 1960s by U.S. military satellites watching for Soviet nuclear tests. They've been a source of scientific controversy ever since.

Many astronomers think GRBs happen when a massive star--one with, say, 50 times the mass of our sun--runs out of nuclear fuel. The star's core then collapses, producing the biggest and brightest sort of stellar explosion known to science. How bright? Try a million trillion times as bright as the sun. And what's left after the blast is another mysterious stellar entity: a black hole.

Learn more about GRBs

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The Ships Beneath San Francisco

Construction workers building a high-rise, 650-unit condo complex in San Francisco have found something big beneath the street: the stern of a 125-foot wooden sailing ship dating back to California's Gold Rush.

Archaeologists excavating the ship say it was likely built in the 1820s, maybe as early as 1810. But it probably didn't make the trip to San Francisco until after 1848. That year, when San Francisco was a tiny village of less than a thousand people, a man noticed a nugget in a stream outside a sawmill he had been hired to build--and started the Gold Rush.

In 1849, more than 800 ships sailed to San Francisco, carrying "49ers" scrambling for a share of the hills' gold. Tens of thousands of people flocked in, and then headed toward what folks called the "Mother Lode." Gold-fevered crews left the ships along with the passengers, and before long, the city's cove was so full of abandoned ships that "ship-breaking yards" were doing brisk business breaking down vessels for timber and scrap.

Experts say the ship discovered under San Francisco now is at the site of one of those old ship-breaking yards. They say there are dozens more ships beneath the streets, too--relics of the lure of gold and the start of the city.

Meet the 49ers

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Thoroughbred Super Stud

There are about half a million thoroughbred racehorses in the world. And, according to a new genetic study, fully 95 percent of them descend from just one super stud.

In fact, virtually all today's thoroughbreds come from just 28 "founder" horses: 3 sterling stallions and 25 well-built mares. But the big daddy was the Darley Arabian. Born in Syria in 1700 and brought to England 1704, the Darley Arabian fell in love with multiple English mares from 1706 to 1719--and made sure that his genes define today's thoroughbreds.

That's pretty much how the thoroughbred breed got its start--with Arabian stallions impregnating English mares to please British aristocrats hooked on "the sport of kings." There are all sorts of horses, from quick and agile quarter horses to noble Arabians, but thoroughbreds were bred specifically for speed and endurance.

Thoroughbreds came to the United States in 1730, when a son of the Darley Arabian came to Virginia. Surprisingly, horses in general didn't come to the Americas until Spanish conquistadors came a-calling in the early 16th century. Before that, the people here were horseless--even Native American tribes famous for their horsemanship today. There were modern horses in the Americas before 10,000 years ago, but they disappeared for reasons still unknown.

See all kinds of horses


"The real voyage of discovery consists not in seeking new landscapes but in having new eyes."
--Marcel Proust


Michael Himick and Steve Sampson
September 16, 2005

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