61 results found.
... Science Frontiers ONLINE No. 60: Nov-Dec 1988 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Asteroids That Turn Into Comets Even though Chiron is large (about 200 kilometers in diameter) and a bit dark for a rocky asteroid, astronomers have been quite comfortable with calling it an asteroid. True, its orbit between Saturn and Uranus is unusual, but what else could it be but an asteroid? A comet, that's what! Recently, the brightness of Chiron has doubled, suggesting that it has expelled considerable gas and dust -- a characteristic of comets, according to mainstream thinking. Another peculiar aspect of the phenomenon is that Chiron is now located 12 A.U . from the sun (12 earth orbits out). Conventional wisdom has it that solar heating is too weak at that distance to vaporize cometary ices. However, other comets, such as Schwassmann-Wachmann 1, have displayed comas even farther away from the sun. Thus, we have two possible anomalies here: (1 ) The existence of a huge cometlike asteoid in a peculiar orbit (2 ) A mechanism that expels gas and dust from comets at great distances from the sun. The blurring of the distinctions between asteroids and comets is aggravated by the recognition that some other asteroids produce streams of particles that create meteor showers; that is, some asteroids are not merely associated with meteor streams, they actually create them, just as comets expel ice and rocky debris. Some bold astronomers now ask whether asteroids are all burntout comets. ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf060/sf060p04.htm
... planets would be merely failed stars. The advantages of this change of perspective are threefold: (1 ) All five central bodies are now compositionally similar as a class, (2 ) In each of the five systems, the angular momentum of the central body is greater than that of its satellites, whereas in the unitary solar system the angular momentum of the nine planets is much greater than that of the sun -- an embarrassing anomaly. (3 ) A final "bonus" appears when the distances of the satellites in the five systems are plotted, as indicated, and compared. The arrangement of the four terrestrial planets (the "solar satellites") closely resembles the distribution of Jupiter's four Galilean satellites. There are loose ends, to be sure, like Pluto and Saturn's rings, but the idea seems worth studying further. (Cole, G.H .A .; "Dynamical Form of the Solar System," Observatory, 105:96, 1985.) Comment. The arrangement of satellites in the figure may have no physical significance, but if you like Bode's Law you should appreciate the situation. Reference. For more information on the book The Moon and the Planets, visit: here . Distribution of orbital radii (r ) of central body satellites, where R is measured in terms of central body radii. Cole terms the similarities 'remarkable'. From Science Frontiers #42, NOV-DEC 1985 . 1985-2000 William R. Corliss ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf042/sf042p08.htm
... " Instruments on satellites (gamma-ray spectrometers) have detected so much aluminum-26 that radical hypotheses seem required. The problem is that aluminum26 is radioactive with a half-life of only about 1 million years -- a very short time astronomically speaking. The aluminum-26 cannot be primordial solar-system stuff; it cannot even be 10 million years old. It had to be created somewhere nearby recently. The best aluminum-26 factory conceived so far is a nova in our vicinity. (Anonymous; "Are We inside a Supernova Remnant?" Sky and Telescope, 69:13, 1985.) Comment. A nova close enough to engulf the earth with its debris must have had a profound effect on the earth and its cargo of life -- perhaps on Saturn's rings, too. See next item . From Science Frontiers #39, MAY-JUN 1985 . 1985-2000 William R. Corliss ...
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... speaking, a tiny fraction would be captured by the earth's gravitational field. Some of these would fall to earth; others would remain in orbit. Now, the reverse scenario has been investigated numerically. S.A . Phinney and colleagues at the University of Arizona have calculated what would happen to small chunks of the earth's crust if a large meteor impact excavated a 60milewide crater. "Phinney's group used a computer to calculate where 1,000 particles would go if ejected from Earth in random directions, moving about 2.5 kilometers per second faster than the minimum speed necessary to escape. Of the 1,000 hypothetical particles, 291 hit Venus and 165 returned to Earth; 20 went to Mercury, 17 to Mars, 14 to Jupiter and 1 to Saturn. Another 492 left the solar system completely, primarily due to gravitational close encounters with either Jupiter or Mercury that 'slingshot' them on their way." (Eberhart, Jonathan; "Have Earth Rocks Gone to Mars?" Science News, 135:191, 1989.) Comment. One implication from the preceding analysis is that terrestrial bacteria and spores could well have infected every planet in the solar system and perhaps even planets in nearby star systems! Conceivably, if other star systems had histories like ours, biological traffic might be quite heavy in interstellar space. In fact, extraterrestrial life forms may be arriving here continually; and we may be such ourselves! From Science Frontiers #63, MAY-JUN 1989 . 1989-2000 William R. Corliss ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf063/sf063a07.htm
... was believed to be about 17 hours. This was just the spin rate needed by theorists to explain why Neptune radiates much more heat than Uranus. It seems that spin rate is related to the mixing of a planet's molten innards, which in turn affects the rate at which heat reaches the surface where it is radiated away. With Neptune's period now pegged at 16 hours by Voyager's measurements, the mixing-cooling theory is in trouble. The magnetic-field situation is in even worse shape. When planetary scientists found that Uranus' magnetic field was tilted 60 from the axis of rotation, they worried a bit but didn't think that this one exception would overthrow the favored dynamo theory of field generation. After all, the magnetic fields of Jupiter, Saturn, and earth are reasonably well-behaved. But Neptune's field is now found to be misaligned by 50 ! The confidence of the planetologists has now been shaken. What, if anything, is different about Neptune and Uranus? It may just be that we don't really know how the magnetic field of any planet is generated. (Kerr, Richard A.; "The Neptune System in Voyager's Afterglow," Science, 245:1450, 1989.) Reference. The anomalies of Neptune and the other planets are cataloged in our book: The Moon and the Planets. To order, visit: here . From Science Frontiers #66, NOV-DEC 1989 . 1989-2000 William R. Corliss ...
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... an asteroid that seems to be mostly metal (probably iron). This is the asteroid Gaspra, some 13 kilometers across, that the Galileo spacecraft encountered in August 1992 on its way to Jupiter. Scientists had not expected Galileo's magnetometer to flicker as it passed Gaspra at a distance of 1600 kilometers -- but it did. In fact, considering the inverse square law and Gaspra's small size, it was a magnetic wallop. Thus, Gaspra is the first known magnetic asteroid; and it is probably mostly metal. (Kerr, Richard A.; "Magnetic Ripple Hints Gaspra Is Metallic," Science, 259: 176, 1993.) At the low end of the density spectrum, we now find that Pluto's moon, Charon, and some of Saturn's moons have very low densities (1 .2 -1 .4 ), meaning they are probably mostly water ice. Such density figures come from direct observation of these objects' volumes combined with mass estimates from their orbital dynamics. (Crosswell, Ken; "Pluto's Moon Is a Giant Snowball," New Scientist, p. 16, November 21, 1992.) Comment. How did this curious mix of ice and iron objects originate? Did some ancient collision demolish a planet with an iron core (like the earth"s ) and an icy exterior? From Science Frontiers #86, MAR-APR 1993 . 1993-2000 William R. Corliss ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf086/sf086a04.htm
... visages to our telescopes. Mars is a classic case, being much more heavily cratered in its southern hemisphere than its northern. But the dichotomies are not restricted to cratering, as we shall now see. Neptune . Recently, H.B . Hammel, using the University of Hawaii's 2.2 -meter telescope, discovered that Neptune's northern hemisphere is now brighter than its southern -- something never observed before. During the past eight years, the southern hemisphere has been consistently brighter, although the hemispheres were of roughly equal brightness during the late 1970s. The cause of these brightness changes remains a mystery. (Cowen, Ron; "Neptune's Northern Half Grows Brighter," Science News, 144:287, 1993.) Iapetus . This satellite of Saturn is dark on one half and light on the other. Quantitatively speaking, the bright side reflects ten times more incident light than the other. An explanation is suggested by the fact that the dark side points in the satellite's direction of motion. A recent study of 12 Voyager images of Iapetus also imply an exogenous (externally imposed) origin of the dark surface, because they show a gradual rather than sharp transition between the dark and light regions. The thought of planetary scientists is that micrometeoroids bombard the leading hemisphere of Iapetus preferentially and in the process volatilize considerable surface material. The residual deposit: ". .. may be an example of the dark, reddish, possibly organic-rich material which is found on other satellites in the outer solar system and on the D ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf091/sf091a04.htm
... Science Frontiers ONLINE No. 102: Nov-Dec 1995 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Ice "meteorites" fall When chunks of ice much larger than those oftenreported "softballsized" hailstones fall, they are termed "hydrometeors." Many hydrometeors have been reported in the meteorological journals. (See GWF1 in Tornados, Dark Days...*) While some of these large chunks can be blamed on aircraft with leaky toilets, many others cannot be explained so easily. Some may truly come from deep space. Seeing that comets and Saturn's rings are composed mostly of ice, there seems to be no shortage of ice in outer space. It is therefore strange that air-craft are routinely blamed for all falls. A Reuter's dispatch from Beijing has described a recent triplet of possible hydrometeors: "Chinese experts have recovered what they believe to be chunks of meteoric ice that fell to Earth in Zhejiang Province, Xinhua news agency said. Amateur geologist Zhong Gongpei was nearby March 23, when farmers saw three large chunks of ice crash with a whoosh into paddy fields at Yaodou village, Xinhua said late Saturday. .. .. . "' According to witnesses, it fell with a 'whoo-ing' sound, with a cloudy streak, then came crashing down into three fields about one kilometre apart," Xinhua said." "Zhong rushed to the scene, recovered two pieces and sent both to Purple Mountain [Observatory] on March 29 with the aid of a frozen- ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf102/sf102g15.htm
... some of the stars. Don't worry that the Oklo phenomenon might occur today on the earth's surface. The concentration of fissionable U-235 has fallen considerably in the last 2 billion years due to its radioactive decay. But, deep inside the earth and other astronomical bodies, nuclear criticality might still be possible due to different pressures, densities, etc. In a stimulating and generally overlooked paper in Eos, J.M . Herndon proffers four important natural phenomena that may involve natural fission reactors. Geomagnetic reversals . In the deep earth, where pressures and densities are high, natural nuclear reactors may generate intermittent bursts of heat -- just as they did at Oklo -- and thereby cause the earth's dynamo to falter and reverse. Planetary heating . Jupiter, Saturn, and Neptune emit much more energy than they receive from the sun. Natural nuclear reactors could be the reason. Stellar thermonuclear ignition . Astronomers assume that the high temperatures required to ignite the thermonuclear reactions powering stars come from gravitational collapse, but this source does not seem adequate to some scientists. Nuclear fission reactors could ignite stars just as they do H-bombs. Missing matter . Natural nuclear reactors are finicky. There may be many star-sized, non-luminous objects out there that were never ignited and that we cannot see through our telescopes. (Herndon, J. Marvin; "Examining the Overlooked Implications of Natural Nuclear Reactors," Eos, 79:451, 1998.) Comments. Two additions to Herndon's list. Evolution of terrestrial life . Nuclear ...
Terms matched: 1 - Score: 13 - 15 May 2017 - URL: /sf121/sf121p02.htm
... Science Frontiers ONLINE No. 8: Fall 1979 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Rings of uranus: invisible and impossible?Now that they have discovered nine rings around Uranus, astronomers are having trouble explaining them. First, if they are made up of small chunks of matter, the laws of celestial mechanics dictate that they should quickly spread out radially into much wider rings in just a decade or two. In other words, if the rings are ancient they should not have maintained their present form. Second, the rings are invisible when one would expect them to be bright like Saturn's . Yet, they reflect less light than the blackest coal dust. T.C . Van Flandern proposes that each ring is actually a single satellite, so small that we cannot see it, and that it sheds gases as it orbits. This small solid body would make the celestial mechanics people happy, and the gases would be invisible to the eye but still absorb light, making the ring of gases detectable when Uranus occults a star. (Van Flandern, Thomas C.; "Rings of Uranus: Invisible and Impossible?" Science, 204:1076, 1979.) Comment. An alternative explanation is that the rings are recently acquired and will soon disappear. An 1847 observation of a ring around Uranus exists, but a datum this old carries little weight. See our Catalog: The Moon and the Planets for this old sighting. This book is described here . From Science Frontiers #8 , Fall 1979 ...
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... ISBN 915554-24-0 , 7x10 format. Unknown Earth: A Handbook of Geological Enigmas Out of print Hardcover, 833 pages, January 1980, ISBN: 0-915554-06-2 Astronomy Catalogs For a full list of astronomy subjects, see here . The Moon and the Planets; A Catalog of Astronomical Anomalies Sorry: Out of Print. No longer available. From our own moon's cratered surface to the red, rock-strewn plains of Mars, the Solar System is a fertile field for scientific research. Despite centuries of observation, each new spacecraft and telescope provides us with new crops of anomalies [Picture caption: One drawing of the Venusian radial spoke system] Typical subjects covered: The ashen light of Venus * The Martian 'pyramids' * Kinks in Saturn's rings * Continuing debate about the Voyager life-detection experiments * Neptune's mysterious ring * Evidence of water on Mars * The grooves on Phobos * The two faces of Mars * Lunar clouds, mists, "weather" * Ring of light around the new moon * Dark transits of Jovian satellites * Io's energetic volcanos * Jupiter as a "failed star" * Venus-earth resonance Comments from reviews: "The author is to be commended for his brilliantly conceived and researched volume", Science Books. 383 pages, hardcover, $18.95, 80 illustrations, 4 indexes 1985. 988 references, LC 85-61380, ISBN 915554-19-4 , 7x10 format. The Sun and Solar System Debris: A Catalog of Astronomical Anomalies Sorry ...
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