What was the subject of astronomer Fred Whipple's 'Dirty Snowball' hypothesis?
"medieval European chroniclers, but were not recognized as reappearances of the same object at the time. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. During its 1986 apparition, Halley's Comet became the first comet to be observed in detail by spacecraft, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail formation. These observations supported a number of longstanding hypotheses about comet construction, particularly Fred Whipple's ""dirty snowball"" model, which correctly predicted that Halley would be composed of a mixture"
"but since 1992 over 10,000 objects have been found in that region of space. One source of confusion though is that objects like Sedna are not predicted in a model using existing Solar System bodies. (see also Planet Nine) ""Whipple"" would orbit in a halo orbit around the Earth–Sun and have a photometer that would try to detect Oort cloud and Kuiper belt objects (KBOs) by recording their transits of distant stars. It would be designed to detect objects out to 10,000 AU. Some of the mission goals included directly detecting the Oort cloud for the first time and determining"
"to counter the effect of the increasing heat flow from the Sun. However, the term Snowball Earth is more commonly used to describe later extreme ice ages during the Cryogenian period. There were four periods, each lasting about 10 million years, between 750 and 580 million years ago, when the earth is thought to have been covered with ice apart from the highest mountains, and average temperatures were about . The snowball may have been partly due to the location of the supercontintent Rodinia straddling the Equator. Carbon dioxide combines with rain to weather rocks to form carbonic acid, which"
"1940 Whipple 1940 Whipple, provisional designation , is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 35 kilometers in diameter. It was discovered on 2 February 1975, by the Harvard College Observatory at its George R. Agassiz Station near Harvard, Massachusetts, in the United States, and named after astronomer Fred Whipple. ""Whipple"" orbits the Sun in the outer main-belt at a distance of 2.9–3.3 AU once every 5 years and 4 months (1,956 days). Its orbit has an eccentricity of 0.06 and an inclination of 7° with respect to the ecliptic. The first used observation was"
"130,000 ppm, which is considered by to be unreasonably large. Strontium isotopic data have been found to be at odds with proposed snowball Earth models of silicate weathering shutdown during glaciation and rapid rates immediately post-glaciation. Therefore, methane release from permafrost during marine transgression was proposed to be the source of the large measured carbon excursion in the time immediately after glaciation. Nick Eyles suggest that the Neoproterozoic Snowball Earth was in fact no different from any other glaciation in Earth's history, and that efforts to find a single cause are likely to end in failure. The ""Zipper rift"" hypothesis"
"Whipple (spacecraft) Whipple mission is a proposal for a space observatory in the NASA Discovery Program 2014 announcement of opportunity. The observatory would try to search for objects in the Kuiper belt and the theorized Oort cloud by doing a blind occultation observation. Although the Oort cloud was hypothized in the 1950s, it has not actually been directly observed. The mission overcomes the hurdle of looking by looking for brief moments where the objects would block the light of background stars, rather than would light that exceeds the abilities of current telescopes. The Kuiper belt was also once only predicted,"
"supercontinent Gondwana. Snowball Earth The Snowball Earth hypothesis proposes that Earth's surface became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago). Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean and emphasize the difficulty of escaping an all-frozen condition. A number of unanswered questions remain, including whether the Earth"
"Snowball Earth The Snowball Earth hypothesis proposes that Earth's surface became entirely or nearly entirely frozen at least once, sometime earlier than 650 Mya (million years ago). Proponents of the hypothesis argue that it best explains sedimentary deposits generally regarded as of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record. Opponents of the hypothesis contest the implications of the geological evidence for global glaciation and the geophysical feasibility of an ice- or slush-covered ocean and emphasize the difficulty of escaping an all-frozen condition. A number of unanswered questions remain, including whether the Earth was a"
"to an ultra-greenhouse effect. Franklyn Van Houten's discovery of a consistent geological pattern in which lake levels rose and fell is now known as the ""Van Houten cycle"". His studies of phosphorus deposits and banded iron formations in sedimentary rocks made him an early adherent of the ""snowball Earth"" hypothesis postulating that the planet's surface froze more than 650 million years ago. Interest in the notion of a snowball Earth increased dramatically after Paul F. Hoffman and his co-workers applied Kirschvink's ideas to a succession of Neoproterozoic sedimentary rocks in Namibia and elaborated upon the hypothesis in the journal ""Science"""
"graduating in 1927. Recollecting his path from mathematics to astronomy, Whipple stated in a 1978 autobiography that his ""mathematics major veered [him] through physics and finally focused on astronomy where time, space, mathematics, and physics had a common meeting ground."" After taking a class in astronomy, he enlisted at the University of California, Berkeley where he obtained his PhD in Astronomy in 1931. While in graduate school, he helped map the orbit of the then newly discovered dwarf planet Pluto. He joined Harvard College Observatory in 1931 and studied the trajectories of meteors, confirming that they originated within the solar"
"creating magnetite, which would then sink and deposit on the floor. Until 1992 it was assumed that the rare, later (younger) banded iron deposits represented unusual conditions where oxygen was depleted locally. Iron-rich waters would then form in isolation and subsequently come into contact with oxygenated water. The Snowball Earth hypothesis provided an alternative explanation for these younger deposits. In a Snowball Earth state the continents, and possibly seas at low latitudes, were subject to a severe ice age circa 750 to 580 million years ago (mya) that nearly or totally depleted free oxygen. Dissolved iron then accumulated in the"
"clusters and supernovas, in high-energy astrophysics, and in developing jet propulsion for spacecraft and airplanes. He was the first to infer the existence of unseen matter and coined the term ""Dark matter"". The lunar crater ""Zwicky"" is also named in his honour. The official naming citation was published by the Minor Planet Center before November 1977 (). 1803 Zwicky 1803 Zwicky, provisional designation , is a stony Phocaea asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered on 6 February 1967, by Swiss astronomer Paul Wild at Zimmerwald Observatory near Bern, Switzerland."
"full snowball, or a ""slushball"" with a thin equatorial band of open (or seasonally open) water. The snowball-Earth episodes are proposed to have occurred before the sudden radiation of multicellular bioforms, known as the Cambrian explosion. The most recent snowball episode may have triggered the evolution of multicellularity. Another, much earlier and longer snowball episode, the Huronian glaciation, which would have occurred 2400 to 2100 Mya, may have been triggered by the first appearance of oxygen in the atmosphere, the ""Great Oxygenation Event"". Long before the idea of a global glaciation was established, a series of discoveries began to accumulate"
"will remove excess energy and the disk will be quite cool in a relatively short period (about 1 mln. yrs.) and the condensation into what Whipple calls cometismals takes place. Aggregation of these produces giant planets which in turn produce disks during their formation from which evolve into lunar systems. The formation of terrestrial planets, comets, and asteroids involved disintegration, heating, melting, solidification, etc. He also formulated the Big Splat or Giant Impactor Hypothesis for the origin of the Moon. The ""capture theory"", proposed by Michael Mark Woolfson in 1964, posits that the Solar System formed from tidal interactions between"
"but nobody would tell me who they were!"" Other commentators have suggested that the children may have been aliens, or inhabitants of a world beneath the Earth. In a 1996 article published in the magazine ""Analog"", astronomer Duncan Lunan hypothesised that the children were accidentally transported to Woolpit from their home planet as the result of a ""matter transmitter"" malfunction. Lunan suggests that the planet from which the children were expelled may be trapped in synchronous orbit around its sun, presenting the conditions for life only in a narrow twilight zone between a fiercely hot surface and a frozen dark"
"some comet drawings were related to the breakup of the progenitor of Encke and the Taurid meteoroid stream. Fred Whipple in his ""The Mystery of Comets"" (1985, page 163) points out that Comet Encke's polar axis is only 5 degrees from its orbital plane: such an orientation is ideal to have presented a pinwheel like aspect to our ancestors when Encke was more active. Comet Encke (and Biela's Comet) had a role in scientific history in the generally discredited concept of ""luminiferous aether"". As its orbit was perturbed and shortened, the shortening could only be ascribed to the drag of"
"Snowball Earth research has suggested that ""oxygen shocks"" and reduced methane levels led, during the Huronian, Sturtian and Marinoan/Varanger Ice Ages, to a world that very nearly became a solid ""snowball"". These epochs are evidence against the ability of the pre Phanerozoic biosphere to fully self-regulate. Processing of the greenhouse gas CO, explained below, plays a critical role in the maintenance of the Earth temperature within the limits of habitability. The CLAW hypothesis, inspired by the Gaia hypothesis, proposes a feedback loop that operates between ocean ecosystems and the Earth's climate. The hypothesis specifically proposes that particular phytoplankton that produce"
"of the Smithsonian Astrophysical Observatory where he developed new methods imaging meteors. He was also president of several commissions at the International Astronomical Union and on NASA's panel for missions to small Solar System bodies. The approved naming citation was published by the Minor Planet Center before November 1977 (). 1940 Whipple 1940 Whipple, provisional designation , is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 35 kilometers in diameter. It was discovered on 2 February 1975, by the Harvard College Observatory at its George R. Agassiz Station near Harvard, Massachusetts, in the United States, and"
"ocean circulation. Synthesised evidence has produced models indicating a ""slushball Earth"", where the stratigraphic record does not permit postulating complete global glaciations. Kirschivink's original hypothesis had recognised that warm tropical puddles would be expected to exist in a snowball earth. The snowball Earth hypothesis does not explain the alternation of glacial and interglacial events, nor the oscillation of glacial sheet margins. The argument against the hypothesis is evidence of fluctuation in ice cover and melting during ""snowball Earth"" deposits. Evidence for such melting comes from evidence of glacial dropstones, geochemical evidence of climate cyclicity, and interbedded glacial and shallow marine"
"model introduced Edward Norton Lorenz's concept of intransitivity indicating that there could be a major jump from one climate to another, including to snowball earth. The term ""snowball Earth"" was coined by Joseph Kirschvink in a short paper published in 1992 within a lengthy volume concerning the biology of the Proterozoic eon. The major contributions from this work were: (1) the recognition that the presence of banded iron formations is consistent with such a global glacial episode, and (2) the introduction of a mechanism by which to escape from a completely ice-covered Earth—specifically, the accumulation of from volcanic outgassing leading"
"with a ballistic Whipple shield (unless it is transparent). Below Earth-altitude, pieces of debris are denser than meteoroids; most are dust from solid rocket motors, surface erosion debris like paint flakes, and frozen coolant from RORSAT (nuclear-powered satellites). For comparison, the International Space Station orbits in the range, and the 2009 satellite collision and 2007 antisat test occurred at altitude. The ISS has Whipple shielding; however, known debris with a collision chance over 1/10,000 are avoided by maneuvering the station. The Kessler syndrome, a runaway chain reaction of collisions exponentially increasing the amount of debris, has been hypothesized to ensue"
"of the Cold War. Moonwatch was the brainchild of Harvard astronomer Fred L. Whipple. In 1955, as the recently appointed director of the Smithsonian Astrophysical Observatory in Cambridge, MA, Whipple proposed that amateurs could play a vital role in efforts to track the first satellites. He overcame the objections of colleagues who doubted ordinary citizens could do the job or who wanted the task for their own institutions. Eventually, Whipple carved out a place for amateurs in the IGY. In the late 1950s, thousands of teenagers, housewives, amateur astronomers, school teachers, and other citizens served on Moonwatch teams around the"
"of Hexagonal Snow""). In this treatise, he published the first description of the hexagonal symmetry of snowflakes and, extending the discussion into a hypothetical atomistic physical basis for the symmetry, posed what later became known as the Kepler conjecture, a statement about the most efficient arrangement for packing spheres. In 1611, the growing political-religious tension in Prague came to a head. Emperor Rudolph—whose health was failing—was forced to abdicate as King of Bohemia by his brother Matthias. Both sides sought Kepler's astrological advice, an opportunity he used to deliver conciliatory political advice (with little reference to the stars, except in"
"and which showers are established. A meteor shower is the result of an interaction between a planet, such as Earth, and streams of debris from a comet. Comets can produce debris by water vapor drag, as demonstrated by Fred Whipple in 1951, and by breakup. Whipple envisioned comets as ""dirty snowballs,"" made up of rock embedded in ice, orbiting the Sun. The ""ice"" may be water, methane, ammonia, or other volatiles, alone or in combination. The ""rock"" may vary in size from that of a dust mote to that of a small boulder. Dust mote sized solids are orders of"
"became the first totally automatic robotic observatory in the world. The Fred Lawrence Whipple Observatory is located on the mountain. The prime mover for the mountain's observatory was Fred Whipple, a professor at Harvard University who was in charge of a small 25 inch mirror telescope in Cambridge, Massachusetts. In Cambridge the ambient light caused light pollution that limited the telescope's usefulness. That led to engineer Tom Hoffman being appointed by Whipple to search for a site in the U.S. that would provide a clear view of the sky at a high elevation, with minimal surrounding light pollution. After searching"
"was much higher than the number based on telescope observations. Such a high flux presented a very serious risk to missions deeper in space, specifically the high-orbiting Apollo capsules. To determine whether the direct measurement was accurate, a number of additional studies followed, including the Pegasus satellite program. These showed that the rate of meteors passing into the atmosphere, or flux, was in line with the optical measurements, at around 10,000 to 20,000 tons per year. Whipple's work pre-dated the space race and it proved useful when space exploration started only a few years later. His studies had demonstrated that"
"object could come from the Hills cloud, but other scientists like California Institute of Technology's Michael Brown also consider other possibilities, including the theory ""it may have formed from debris just beyond Neptune [in the Kuiper belt] and been 'kicked' into its distant orbit by a planet like Neptune or Uranus"". The orbit of currently comes closer to Neptune than any of the other giant planets. More than half of the simulations of this object show that it gets too close to either Uranus or Neptune within the next 180 million years, sending it in a currently unknown direction. This"
"and are pushed outward from the Sun into interstellar space. The interplanetary dust cloud has a complex structure (Reach, W., 1997). Apart from a background density, this includes: In 1951, Fred Whipple predicted that micrometeorites smaller than 100 micrometers in diameter might be decelerated on impact with the Earth's upper atmosphere without melting. The modern era of laboratory study of these particles began with the stratospheric collection flights of D. E. Brownlee and collaborators in the 1970s using balloons and then U-2 aircraft. Although some of the particles found were similar to the material in present-day meteorite collections, the nanoporous"
"63305 Bobkepple 63305 Bobkepple, provisional designation , is a carbonaceous Hygiean asteroid from the outer regions of the asteroid belt, approximately in diameter. It was discovered on 17 March 2001, by astronomer David Healy at the Junk Bond Observatory in Arizona, United States. The asteroid was named after Bob Kepple, co-author of ""The Night Sky Observer’s Guide"". ""Bobkepple"" is a member of the Hygiea family (), a large family of carbonaceous outer-belt asteroids, named after 10 Hygiea, the main belt's fourth-largest asteroid. It orbits the Sun in the outer main-belt at a distance of 2.7–3.7 AU once every 5 years"
"sun at orbit sunset. At dawn of the third and final orbit, Carpenter inadvertently bumped his hand against the inside wall of the cabin and solved a mystery from the previous flight. The resulting bright shower of particles outside the spacecraft - what John Glenn had called ""fireflies"" - turned out to be ice particles shaken loose from the spacecraft's exterior. Near the end of the flight, Carpenter found that by banging his hand against the wall of the capsule, he could shake more ""fireflies"" loose. At first, it was thought that the particles could be marker dye or shark"
"event in many cases. Comets can produce debris by water vapor drag, as demonstrated by Fred Whipple in 1951, and by breakup. Each time a comet swings by the Sun in its orbit, some of its ice vaporizes and a certain amount of meteoroids will be shed. The meteoroids spread out along the entire orbit of the comet to form a meteoroid stream, also known as a ""dust trail"" (as opposed to a comet's ""dust tail"" caused by the very small particles that are quickly blown away by solar radiation pressure). The frequency of fireball sightings increases by about 10-30%"
"interactions with Mars's thin atmosphere, Shklovsky concluded that Phobos might be a hollow metal object as little as thick - an unambiguously artificial object. Though Shklovsky later claimed to Patrick Moore that the paper was nothing more than a practical joke, it was taken seriously by others including Carl Sagan and national science adviser Fred Singer, who commented: If the satellite is indeed spiraling inward as deduced from astronomical observation, then there is little alternative to the hypothesis that it is hollow and therefore Martian made. The big 'if' lies in the astronomical observations; they may well be in error."
"to security concerns. Hay's character during his radio series was called Dr. Muffin, a name chosen so that the students could mock him with the name ""Old Crumpet"". Aside from his day job as a comedian, Hay was a dedicated and respected amateur astronomer. He constructed a personal observatory in his garden in Mill Hill and built a glider in 1909. He became a Fellow of the Royal Astronomical Society in 1932 and is noted for having discovered a Great White Spot on the planet Saturn in 1933. The spot lasted for a few months and then faded away. He"