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A moon rock of ages

Evidence of Starbucks on Mars? Probably not. But there have been some surprising recent discoveries about our solar system.

August 23, 2011
  • The moon rises over Los Angeles City Hall. The new analysis could leave scientists who model the moon's formation "scratching their heads," said an isotope geochemist who was not involved in the study.
The moon rises over Los Angeles City Hall. The new analysis could leave scientists… (Scott Harrison / Los Angeles…)

We just can't get our solar system right. First, the beloved Pluto is downgraded to "dwarf planet." Now it turns out that the moon may be 200 million years younger than scientists estimated.

A study in the journal Nature, based on a new analysis of a lunar rock brought back to Earth in 1972 by Apollo 16 astronauts, indicates that the moon could be a more youthful 4.36 billion years old — and that the process by which it was formed happened later than scientists thought. Or possibly this lunar rock, part of the moon's crust, isn't exactly what scientists thought it was. Maybe the crust wasn't formed by a magma ocean after all. "And that's a big deal," said Lars Borg, the lead author of the study and a geochemist at Lawrence Livermore National Laboratory.

Although not a done deal. Scientists will keep studying and debating this. "I'm running a lunar sample on the mass spectrometer as we speak," noted Borg.

And the next solar system surprise? The rings of Saturn aren't really rocks and dust but instead a billion pieces of Styrofoam from discarded coffee cups?

What else might need to be rethought? For centuries, scientists have been making paradigm-shifting discoveries that reordered our sense of the universe and our place in it. Otherwise, Earthlings would still think that the sun and the planets revolved around Earth, forcing scientists and philosophers to concoct increasingly elaborate explanations for observations of celestial movements that don't fit that worldview.

Consider how our understanding of Mars has changed in the last few decades. It's dusty … it was wet … wait, is there salty water now? Scientists have long known that there's ice at the poles. But in 2006, NASA's Spirit rover discovered evidence of past hydrothermal activity — like hot springs. Three years later, it found evidence that there had been snow or ice close to the planet's equator. If Spirit hadn't conked out last year, presumably battered by a brutal Martian winter, surely it would have discovered evidence of a Starbucks.

Maybe not. But the beauty of science is how it embraces redefinition, even if it's disconcerting. And these days, a scientist rarely risks being brought to trial for it — as Galileo was. They must just weather debate. "In science, nothing is ever taken to be absolute truth," said Borg.

That is definitely true.

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