![]() ![]() Hartmann (copyright 2001, all rights reserved). Are they still lurking unseen beyond the orbits of Neptune and Pluto? This painting of the early solar system appears courtesy of scientist and artist William K. Right: Planetesimals - the building-blocks of planets - were plentiful during the early days of our solar system. Nowadays they occasionally fall toward the Sun and become short-period comets. The ones beyond Neptune, Kuiper speculated, never stuck together, remaining instead primitive and individual. Kuiper's solution was a population of dark comets circling the Sun in the realm of Pluto - leftovers from the dawn of our solar system when planetesimals were coalescing to make planets. Short-period comets evaporate so quickly compared to the age of the solar system that we shouldn't see any, yet astronomers routinely track dozens of them. Astronomers call them "short-period comets," although "short-lived" is more to the point. They encounter the Sun so often that they quickly evaporate - vanishing in only a few hundred thousand years. It was the only way, he figured, to solve a baffling mystery about comets: Some comets loop through the solar system on periodic orbits of a half-dozen years or so. That discovery marked our first glimpse of the long-sought Kuiper Belt, named after Gerard Kuiper who, in 1951, proposed that a belt of icy bodies might lay beyond Neptune. The bright streak in this CCD image is an asteroid, faster-moving that 1992 QB1 because it lies much closer to the Sun. It took five years, looking off-and-on through the University of Hawaii's 2.2 m telescope, but they finally found what they were after: a reddish-colored speck 44 AU from the Sun - even more distant than Pluto! Jewitt (University of Hawaii) and Luu (UC Berkeley) wanted to name their find "Smiley," but it has since been cataloged as "1992 QB1."īelow: A 1992 discovery image of 1992 QB1 (indicated by the arrow) captured by Jewitt and Luu using the University of Hawaii's 2.2 m telescope on Mauna Kea. Beginning in 1987 they had doggedly scanned the heavens in search of dim objects beyond Neptune. The first of these strange bodies, which astronomers call Kuiper Belt Objects (KBOs), came to light in 1992, discovered by Dave Jewitt and Jane Luu - a pair of scientists who didn't believe the outer solar system was empty. ![]() Indeed, say astronomers, it may be only a matter of time before observers spot one as big as Pluto itself. Most are about the size of small asteroids (a few km to a few hundred km wide), and a few have emerged recently that are 30% to 50% as wide as the planet Pluto (2274 km). ![]() Probably they're a mixture of ice, rock, and dust. It's hard to know exactly what they're made of because their insides are concealed by a layer of ruddy organic goop. Sign up for EXPRESS SCIENCE NEWS deliveryĪs seen from Earth those dim companions of Pluto appear to dark comets. Lately astronomers have found that the frontier beyond Neptune, far from empty, is swarming with thousands of dark and mysterious objects - enough to make a star-bound explorer pause for a second look. Reproduced courtesy of Dave Jewitt.īut wait! Maybe the outer solar system isn't so dull after all. Better perhaps to pass them by and head for a far-away star.Ībove: An artist's visualization of the outer solar system. And, indeed, for most of the past century astronomers figured there was little enough to see: only one small icy planet, Pluto, and its oddball moon Charon. And it's so cold that the atmosphere of Pluto - the only one of the nine planets orbiting so far from the Sun - lies frozen on the ground most of the time.Ī spaceship exploring the outer reaches of our solar system could go a long time without seeing much. The Sun, so cheerful and warming here on Earth, is merely the brightest star in the night sky there. September 13, 2001: Billions of kilometers from Earth, beyond the orbit of Neptune, lies perhaps the most forbidding part of our solar system, a vast realm so cold and dark it sparks a frisson of dread among thoughtful astronauts. ![]()
0 Comments
Leave a Reply. |