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More About Quaoar
The Solar System >
There's a newfound fuzzy object way out in our
solar system that's just made things a little bit clearer.
Last week planetary scientists Mike Brown and Chad Trujillo of Caltech
announced their discovery of Quaoar, the largest solar system body found
since the discovery of Pluto way back in 1930.
Using the old 48-inch Oschin Telescope on Palomar Mountain fitted with new imaging equipment, they noticed last June a new, extremely faint object in the sky just northeast of the constellation Scorpio.
Searching back through archives at Palomar, Brown and Trujillo dug up several more faint images previously taken of this rocky body dating all the way back to 1982. It had been overlooked! But, how?
Quaoar is one small rock, half the size of Pluto, and on average farther from Pluto, so very little light reaches it. Moreover, the organic material on the surface has most likely been degraded to a fare-thee-well by 4 billion years of ultraviolet bombardment from the distant sun, probably resulting in tar-like substances on some of the surface. That would make it even dimmer.
So that it managed to disappear amongst the background stars for so long is not surprising. That Brown and Trujillo actually found this tiny slow-moving dark rock is a reflection of their equipment and the tenacity of the astronomers.
"The discovery," says Steven Pravdo of NASA, "is another feather in the cap of the venerable Oschin Telescope and the modern Near-Earth Asteroid Tracking camera system."
E. C. Krupp, Director of Griffith Observatory, adds, "The real charm of this discovery is the detection of the object at all. I am delighted with and impressed by the perseverance and diligence of the astronomers who spotted it. Their quiet, painstaking work showcases mindful observation of nature."
The odd thing for most laymen is the reaction from astronomers --- they aren't surprised by this discovery at all. Michael Seeds, astronomer at Franklin and Marshall College sums it up, "If we looked and looked and looked and did not find these objects, the solar system would have to produce a note from its Mama explaining how it lost them."
So what is Quaoar and why is its discovery no surprise to the people who know the skies well? We'll have to go back in time a bit.
Since humans have recorded what is in the heavens, there has been an acknowledgment of the Sun, Moon, and the brighter, naked-eye planets out to Saturn. And there were the occasional strange visitors like comets, to be sure. But that was about it. The skies above were pretty clean and well managed.
Then in 1781 distant Uranus was discovered. Shortly after, Neptune was descried. The solar system was growing. And in trying to find even more planets, new, unexpected findings were made.
In 1801 came the detection of an object between Mars and Jupiter; the first minor planet, christened Ceres, was discovered. Within years, more and more of these huge rocks were seen in an area we now call the Asteroid Belt. As hundreds more were found, there was not so much new excitement as there was a quest to find out what it all meant.
Were all these asteroids potential building blocks of a wannabe planet that just couldn't get it together, or the remains of a planet that was ripped apart, perhaps by Jupiter's intense gravity?
And there was another, related mystery, one which leads us to last week's discovery --- comets. These little critters get the bejeebers blown off them every time they come by the sun. The sun's energy and winds strip a whole lot of dust and water from them giving them their beautiful tails. Sadly, the great loss of "stuff" means they will have relatively short lives.
Moreover, their orbits take them close to the sun, but then far --- I mean billions of miles far - from the sun during the rest of their orbit.
But despite their shrinking population new comets somehow keep showing up from way out there, year after year after year. How, and from where?
"The answer had to be," believes astronomer Andy Young of San Diego State, "that there was a vast supply of comets in cold storage somewhere beyond the region occupied by the planets." Occasionally one would get bumped into an orbit that would take it close to the sun.
Elsewhere in the galaxy we see monstrous, dirty, Frisbee-shaped disks of rocky material around other baby stars, disks where we believe that rocky material is being coalesced into planets. We are led to believe, then, that we probably have a lot of leftovers in our own great freezer, out there beyond Neptune. The comets are just some of those icy chunks that get nudged in toward the sun.
We call our own Frisbee of frozen leftovers the Kuiper Belt, named after Gerard Kuiper who first proposed its existence.
Young adds, "But the leftovers shouldn't
be as small as the average comet; there should be some 'half-baked'
planets that never really grew to planetary size. At the edge of the planetary
system there ought to be a lot of solid bodies, bigger than the average
comet, but smaller than the average planet."
Enter Pluto.
When Pluto was discovered in 1930, astronomers knew something was amiss. It wasn't a gas giant like all the Big Guys out there are; it was a rock smaller than our Moon. And it had a funky lopsided orbit that sometimes took it closer to the sun than Neptune! Pluto was a planetary oddball, a freak.
But maybe no more.
Maybe, as Dr Young points out, Pluto, along with the newly discovered Quaoar are "examples of these intermediate-sized objects. Maybe Pluto was the just the first-found member of that group, and not a freak."
Most astronomers now believe Pluto, with its moon Charon, are a very large "double" Kuiper Belt Object (KBO), some of the leftovers from the infancy of our solar system. There have been many other KBOs, some called Plutinos, found in the last years with the new, modern instruments.
Does that mean Pluto will be downgraded from planet to a "mere" KBO? Krupp says no. "Membership in the Kuiper Belt battalion is no reason to disqualify Pluto as a planet. Pluto's planet-status is now more historical and cultural than physical. I'm a card-carrying member of the Fair Play for Pluto Party. Pluto is the people's planet. It earned that standing through its cultural meaning, and I see no reason to rescind its status now."
So the discovery of Quaoar came as no surprise. But is it important? You bet.
Says Seeds, "The discovery of this object confirms our understanding of how the solar system formed. I'll bet my lunch money that there are even bigger objects to be found. Probably not many, but enough to win a few nice lunches, and further confirm our understanding of the history of our planetary system."
Young concludes, "What's important here is not just 'discovering' an object, but the way in which that object ties together planets, comets, and the history of the whole solar system. It's like filling a hole in a jigsaw puzzle by noticing a piece you didn't see before."
Quaoar is one more piece that fits perfectly into the Great Puzzle.
Posted by Administrator at 2002.10. 2 02:27 PM | Comments (0)
