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A Distant Object Sheds Light On Our Universe

By Joel Achenbach
Washington Post Staff Writer
Wednesday, March 17, 2004; Page C01

One day last November some sunshine zoomed across 8 billion miles of space and slammed into an icy world that no human being had ever seen. The sunshine bounced.

It headed back in the general direction of the sun, still zipping along, when suddenly it careened into the 48-inch mirror in a telescope on top of Mount Palomar, near San Diego. A 171-megapixel camera recorded the light splash. Robotic instruments handled the entire procedure. The astronomer in charge of the observation, Michael Brown, was sleeping in his home in a suburb of Los Angeles.

Now that an earthbound telescope has discovered Sedna, the orbiting Hubble Space Telescope may soon tell us more about it. (Michael Brown -- CalTech/NASA via AP)

NASA discovers new planetoid.

The next morning, Brown went to his office at the California Institute of Technology and, as he always did, ran through the night's data, which had been relayed from Mount Palomar by microwave and Internet. A computer program flagged an unusual source of light that, in three different photographs, appeared to move slowly across the dark night sky. False alarms are part of the trade, but to Brown, a professional hunter of distant worlds, this looked promising.

In class that morning, at the end of his lecture, he told his students that no one had ever detected an object from the Oort cloud, a mysterious region on the outskirts of the solar system. But then he added, "I might have just lied to you, because I think I just found something out there this morning."

That something, confirmed since by several other telescopes, is officially labeled 2003 VB12. Brown would like to name it Sedna, in honor of an Inuit sea goddess. It's three times as far from the sun as Pluto. It's oddly red, like Mars, and of unknown composition. It's at least 800 miles in diameter, and possibly as much as 1,200 miles, a figure that would become more precise if (as is rumored) the Hubble Space Telescope takes a look at it in coming days. Sedna may have a moon.

The Sedna discovery predictably triggered a debate about the difference between a planet and a planetoid (which always sounds insulting) and between Kuiper Belt objects (hundreds found) and Oort cloud objects (hypothetical, unless Sedna is such a thing). What's certain is that the traditional solar system is more interesting than previously imagined, and subject to a kind of suburban sprawl.

More than anything, the Sedna story reminds us that the universe wants desperately to tell us its secrets. The universe is gifted with the greatest information-transfer system: an essentially indestructible packet of light called the photon. When the Creator said, "Let there be light," he quickly added, "Reach out and touch someone."

The eyeball is a catcher's mitt for light, perfectly designed to nab the peak emissions of our particular sun. With the naked eye we can see only a few thousand stars, but we got help. In 1610 Galileo announced that he'd used a new contraption called a telescope to discern mountains on the moon and four objects orbiting Jupiter -- the Galilean moons, as they became known. He peered into the Milky Way and discovered that the fuzzy glow was caused by myriad individual stars. An immense galaxy of worlds suddenly announced itself.

"The information is out there for the taking," says Brad Whitmore, an astronomer at the Space Telescope Science Institute in Baltimore, which conducts the Hubble's science program.

A photon, which is sometimes considered a "particle" of light but also acts like a wave, is astonishingly durable and unflagging. A photon can be absorbed by dust as it travels through space, but it doesn't ever splinter or fracture or crumble into lesser ingredients. Speeding along at 186,000 miles per second, a photon can make it all the way across the universe.

"They go on forever," Brown said yesterday. "It's energy, and unless there's some reason for the energy to dissipate, it will just continue on."

Light carries information. The redshift of galactic light can tell us about the distance to the source. Tiny idiosyncrasies in the spectrum of a packet of light tell us if a reflecting object is particularly laden with, say, carbon, oxygen, iron or whatnot. With a little deduction and extrapolation and an extremely fancy telescope we may someday be able to analyze the atmospheres of planets orbiting distant stars. Certain spectral features of the light might strongly suggest that the planet was an abode of living things, perhaps using photosynthesis as do oxygen-emitting plants on Earth.

(The joke for a long time has been that, if we detect smog on a distant world, it means we have discovered dumb life.)

"All we've got is light," Whitmore says. "We've got to sit here and decipher it as it comes in. We've become experts at deciphering light."

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