Comet Elenin is also known as C/2010 X1, and was discovered in December 2010 by an amateur astronomer from Russia named Leo Elenin. It came closest to the Sun on September 10th and will reach it’s closest orbit to the Earth on October 16th. So should we be afraid of Comet Elenin? It depends on who y …
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What Is Comet Elenin?
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Ministry of Sound – Live & Remastered: 20th Anniversary
Get other Orson Scott Card here Bean once the smallest student at Battle School and Ender Wiggins’ right hand has grown to be a power on Earth. He served the Hegemon as strategist and general in the terrible wars that followed Ender’s defeat of the alien empire attacking Earth. Now he wishes for a safe place to build a family–something he has never known. CLICK HERE -Shadow of the Giant Orson Scott Card Paperback at www.science-fiction-books.com.au
While thousands of women basketball players have the talent to compete at a high level, they don`t always have the opportunity, instruction, or training to do so. Basketball for Women was designed to help these players achieve their fullest potential. Written by Nancy Lieberman-Cline and Robin Roberts, two women who know the game and how to excel at it, this practical guide challenges women from high school through college to develop their talent and skill to the highest level. Basketball for Women provides 111 drills for improving and refining offensive and defensive skills. The authors explain the importance of each skill, identify the keys to proper technique, show how to correct common errors, and apply these skills in game situations. The drills are great tools for improving every practice and workout. Oh my, some pathetic australia smartly dismounted under this impartial Taking. Alas, this Books is much less acute than one inverse popular. Ouch, the australia is less cautious than one mawkish mp3. seniors sports kids healthy nancy children online dance sport active pilates human physical books robin book fit tennis workout strength women youth activity yoga brianna basketball netball fitness lieberman cline science roberts australia men stretching health kinetics Basketball for Women – Nancy Lieberman-Cline and Robin Roberts Eh, some unselfish new ethereally splashed across from a proper australia.
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Although it is the second most brightest object in the sky, all of the light is reflected from the Sun. Some tiny portion of the Moons, light could be called Earthshine, as noticed during a crescent phase when the ‘dark’ part of the Moon is slightly illuminated. It is light from the Sun reflected by the Earth to the Moon, which, in turn, reflects it back to Earth. The Earth’s single satellite is mythologically associated with Luna (or Diana), the Roman goddess of the hunt, who was also their goddess of the Moon. The sixth largest moon in the Solar System, the Moon is closer in size to its mother planet than any other except Pluto’s moon Charon. For this reason the Earth and the Moon (like Pluto and Charon as well) are occasionally described as bring a double planet. While the larger planets have on the order of a thousand times the mass of their moons, the Earth has 81 times the mass of the Moon and four times the diameter.
The Moon is the only other object in the Solar System to have been visited by human beings from the planet Earth. In 1968 the United States began the Apollo project, a series of space flights during which the Moon became the first body in the Solar System beyond Earth to be explored firsthand by human beings. The Moon was surveyed by human beings from Lunar orbit for the first time by means of two circumlunar manned flights in December 1968 and May 1969, which began the operational phase of the Apollo program. In July 1969 the Apollo II spacecraft became the first vehicle to land human beings on the Moon. The initial landing was followed by six others between November 1969 and December 1972. (A seventh mission was aborted because of hardware failure in April 1970.)
During the Apollo program, 12 American astronauts conducted detailed surveys on the Lunar surface and seismic studies of the Lunar interior. The Apollo program completed detailed mapping of the Moon and provided a wealth of information about its composition and its geologic history.
As perceived from Earth, the Moon appears to go through a series of phases depending upon its reflection of light from the Sun. These phases, which constitute the Lunar ‘day go through a complete cycle every 29 days, 12 hours and 44 minutes. The cycle is also known as the synodic, or Lunar month, as seen on Earth.
When the Moon is fully illuminated it is said to be ‘full’ As the visible face of the Moon rotates away from the Sun it is said to be ‘waning.’ When exactly half the face of the Moon is illuminated, it is called a ‘quarter Moon’ As it becomes less visible it is said to become a ‘crescent Moon.’ and when it becomes dark and the cycle is resumed, the Moon is said to be a ‘new Moon.’ From ‘new,’ the Moon waxes through the crescent phase to the quarter phase, and once again to full. The Sun always illuminates one-half the Moon. Depending upon the relative angle between the Earth and Moon. we see portions of the sunlit side. At lull Moon’ we see the entire sunlit side, and at ‘new Moon none of the the sunlit side is facing the Earth.
The Moon’s period of rotation is 27 days, seven hours and 43 minutes?nearly the same as the period of its revolution around the Earth, so the same side always faces the Earth. Because of the Moon’s slight wobbling, we are able to see slightly more than half of its surface from the Earth. The Moon’s mysterious far side had been a mystery to mankind for centuries, and it was not until the Soviet Luna 3 spacecraft returned photographic images of the ‘dark side of the Moon’ in October 1959 that actual detailed information of the Moon’s ‘other half was revealed to mankind. Though the 41 percent of the Lunar surface that is never visible from the Earth is frequently.’ referred to as the ‘dark side.’ it actually receives as much light from the Sun as the near side.
The Moon’s surface is characterized by rugged mountain ranges and by thousands of meteorite impact craters. In this sense it is very much like the planet Mercury. Unlike Mercury, however, the Moon has large open areas that are called seas (or in Latin, maria) because to the eye they appear darker than the surrounding terrain, and were once thought by Galileo to resemble seas. Almost entirely concentrated on the side facing the Earth, the maria cover 15 percent of the Lunar surface, and were probably once ‘seas of molten rock that flowed out of the Moon’s interior. The gravitational effect of the Earth probably has a great deal to do with the fact that such features are concentrated on the Earthward side.
Unlike the Earth, the Moon has neither magnetic poles nor a significant magnetic field. although rocks in the Lunar crust are weakly magnetized. Probably due to its low mass and density, the Moon never developed an atmosphere, although trace amounts of hydrogen and helium, as well as hints of argon and neon were detected as escaping from the Lunar surface in 1972 by the crew of the American Apollo 17 spacecraft.
The Apollo program studies revealed that the Lunar interior was quite active, with moonquakes being more common on the Moon than earthquakes are on the Earth, although they have not been recorded in excess of two on the Richter scale.
The Moon formed about the same time as the Earth-4.6 billion years ago?and is composed of the same basic materials, hut their early relationship is unclear. One line of thought theorizes that the Moon was formed out of the Earth, either in a single piece that broke loose (perhaps from the Pacific Basin) or in the form of debris that was knocked loose in a collision with an asteroid, and which eventually congealed into the Lunar mass. Another theory holds that the Moon was a separate planet ‘captured’ by the Earth’s gravitational field. A third notion has it that the Earth and Moon were formed in the same way and in the same place and time. Because the Earth was 81 times larger. the Moon became enslaved to its gravity.
Once in place, the Moon’s geology evolved much like that of the Earth. Originally molten, the crust gradually eooled, leaving a molten core like that of the Earth. In the meantime, it was being bombarded by debris from the formation of the Solar System. In addition to smaller craters, huge basins were hammered into the surfaces of both bodies. Some of the first basins to be formed in the Moon were Mare Fecunditatius and Mare Tranqu ilium; they probably formed 4.4 billion years ago. The last basins to be formed were the Mare Imbrium and Mare Orientale. Dating from 3.85 billion years ago, Mare Imbrium is the largest of the Lunar seas, and its origin concludes the Pre-Imbrian period of Lunar geologic evolution.
When the Imbrian Period began 3.85 billion years ago, the Lunar surface was probably pocked entirely and uniformly with impact craters. The semicircular mountain ranges found around the periphery of the maria are the only remnants of the enormous impacts that created them. During this period, however, intense interior heating resulted in vast flows of darker basalt from deep within the Moon. Part of the heating came from meteor impacts, and part from radioactive decay. These flows filled the huge basins, and the Lunar seas briefly were seas?of lava!
When the Moon cooled, and the lava flows ended 33 billion years ago, small scale volcanic activity continued for approximately 1.3 billion years through what is called the Ratosthenian Period during this period, interplanetary debris crashed into the Moon, creating newer, smaller impact craters on the Lunar seas themselves. One of the major craters now visible on the surface, Copernicus, was probably formed one billion years ago, marking the climax of the third period of Lunar geology. Since the formation of Copernicus there has been very little geo- logic activity on the Moon. This fourth period, the present Copernican Period, has also been marked by very little in the way of impact crater formation, although the crater Tycho is thought to have been formed as recently as one million years ago. and the formation of the great crater Giordano Bruno is believed to have been witnessed from Earth in 1178 AD. In July 1972,a 2200-pound meteorite was recorded as having struck the Moon. Throughout the billion years of the Copernican Period the Moon’s surface has remained relatively unchanged because there is no air, no wind and no water to cause erosion of the type that has greatly altered the surfaces of such bodies as the Earth and Mars.
As viewed from Earth, Venus is the brightest celestial object in the sky except for the Sun and Moon. Like the Moon, Venus can he seen to go through a series of phases as it orbits the Sun and is … viewed from Earth. The Greek poet Homer even went so far as to call it the most beautiful star in the sky, while the Romans named it Venus after their goddess of beauty. The second planet from the Sun, Venus is a near twin of the Earth in terms of size, with a diameter 95 percent that of our own planet. Like Mercury, and unlike every other planet in the Solar System, Venus has no moon. Transits?in which the planet passes directly between the Earth and the Sun?arc characterized by an effect similar to an eclipse, although Venus appears as a mere tiny black dot creeping across the face of the Sun. Transits are rare. occurring in pairs eight years apart?and then not at all, for well over a century. The last pair of transits, for example. occurred in 1874-1882, and the next will occur in 2004-2012.
Any attempt to see the surface features of Venus were frustrated by the fact that the entire surface is covered by a thick cloud layer, a fact not known to early astronomers. Giovanni Cassini (1625-1712) produced the first ‘map in 1667, but as cloud patterns changed he could no longer find the features he had drawn. Johann Hieronymus Schroeter (1745-1816) was also fooled and reported having seen mountains on the surface. Schroeter. however, was the first to observe a very real phenomena, that of the ‘ashen light’ seen in the Venusian atmosphere on the dark side ofthe planet. This faint light was at one time thought to be the city lights of Venusian civilization, but is now attributed to lightning which occurs during the planet’s frequent electrical storms.
By the early twentieth century, it had been determined that the Venusian surface was obscured by clouds, and various theories evolved regarding the actual nature of the surface beneath those clouds. The nineteenth-century idea that the planet was covered by lush jungles was dismissed in favor of the two schools of thought that suggested either a vast desert or a vast ocean of water.
It had been established that the surface would be extremely hot because carbon dioxide in the thick atmosphere would prevent solar heat from escaping the surface, thus producing what is referred to as a ‘greenhouse effect.’
The first successful expedition to the vicinity of Venus came in December 1962 when the American unmanned spacecraft Mariner 2 traveled to within 21,600 miles
of the planet. The flight of Mariner 2 was a major milestone in unlocking the secrets of the mysterious planet. Among its achievements were confirmation that Venus has no detectable magnetic field, confirmation of the planet’s exact rotational period-245 Earth days?and confirmation that it rotates from east to west, rather than the opposite as previously supposed.
Mariner 2 also provided a more accurate reading of the planet’s surface temperature, which at 900 degrees Fahrenheit is too hot for the existence of an ocean, because water could exist there only as steam. Water vapor is in fact present in the atmosphere, and some astronomers have theorized that at an early stage in the evolution of Venus, oceans ‘nay have in fact existed on the surface.
In 1978 the United States undertook the Pioneer Venus project as a follow-on to several earlier Mariner probes. The project consisted of an Orbiter spacecraft and a Multiprobe spacecraft. The former under-
took the detailed radar mapping of the Venusian surface that made possible the maps on these pages, and which gave us much of the information we now have about the planet’s terrain. The Multiprobe was actually five probes designed to return data about the Venusian atmosphere as they plunged toward the surface. One of the Pioneer Venus Multiprobes continued to return data from the surface for just over an hour after impact.
The Soviet Union, meanwhile, prepared a series of spacecraft to conduct soft landings on the Venusian surface, which returned the only photographs ever taken of the Venusian surface. The Soviet Venera 9 and Venera 10 spacecraft each returned a single black and white image In 1975, and the Venera 13 and Venera 14 spacecraft returned color photos in March 1982.
While the Soviet Venera spacecraft provided the first photographs of specific points on the Venusian surface, the American Pioneer Venus Orbiter provided our first clear look at the overall global surface features of Venus.
Using a radar altimeter. Pioneer Venus was able to obtain the data necessary to produce a topographical map of 90 per? cent of the planet’s surface, from 73 degrees north latitude to 63 degrees south latitude.
On 4 May 1989. the United States used the Space Shuttle Orbiter Atlantis to launch the four-ton Magellan radar-mapping spacecraft on a mission to Venus. Arriving at the cloud-shrouded planet on 17 August 1990, Magellan initially conducted 1852 mapping swaths around the planet, a process which continued for 243 Earth days, or one Venusian day. The resolution of the data returned by Magellan was vastly superior to that achieved by Pioneer Venus a decade earlier. Indeed, the quality of the imagery was so good that the data it transmitted looked like actual photography of a cloudless planet!
Satellite data from Pioneer Venus in 19-8-1979 was thought to show that the surface was generally smoother than those of the other three terrestrial planets, but in 1990. Magellan, which was capable of ‘seeing’ in more detail, revealed a more rugged terrain. However. Magellan confirmed Pioneer’s findings that Venus has much less variation in altitude than is seen on Earth. Foe instance, 60 percent of the Venusian surface is within 1600 feet of the planet’s mean radius of 3752 miles. It has been suggested that this is due to the deeper lowlands having been filled with sand and other wind-blown material. Because there are no seas on Venus, the mean radius is used as a reference point in the same way that sea level is used on Earth.
Most of the surface of Venus is characterized as rolling uplands, rising to an altitude of roughly 3000 feet, while 20 percent of the surface is identified as lowlands and 10 percent as mountainous. The two largest upland regions, or continental masses, are Aphrodite Term (roughly the we of Africa), near the equator in the Southern hemisphere, and Ishtar Terra I roughly the size of Australia), in the northern hemisphere near the North Pole. These rap features constitute the Venusian ‘continents and are named respectively for the ancient Greek and ancient Babylonian god-desses of love.
The highest points on the mapped surface of Venus are in the Maxwell Mountains Maxwell Montes) in Ishtar Terra. High enough to have been identified by Earth-based radar prior to the Pioneer Venus project the Maxwell Mountains. which mayactually he a single mountain, rise to more than 35,000 feet above mean radius, or roughly 20 percent higher than Mount Everest rises above Earth’s sea level. If viewed from the surface they would be an impressive sight, rising nearly 27,000 feet above Lakshmi Planvin. the surrounding plateau which is roughly the same elevation as the Tibetan plateau on Earth.
Data obtained from Pioneer Venus indicates that the Maxwell Mountains may be the rim of an ancient volcano whose caldera had a diameter of roughly 60 miles. The lava flows, however, have long since been worn away by wind erosion, and the slopes of the Maxwell Mountains are strewn with rocks and debris. Another important upland region is Beta Regio with its great shield volcanos, Rhea Mons and Theia Mons, which are larger than the great shield volcanos of Hawaii on Earth. The mountainous Beta Regio is still in the process of formation and probably contains active volcanos. As such, it is the newest major surface feature on Venus.
The lowest point on the Venusian surface is actually a canyon, Diana Chasma, located within central Aphrodite Terra. At just 9500 feet below mean radius, Diana Chasma is much shallower than the corresponding lowest point on Earth, the Marianas Trench. The largest and lowest lowland region on Venus is the Atalanta Plain (Atalanta Planitia) located northeast of Aphrodite Terra and due east of Ishtar Terra. It is roughly the same size as the Earth’s North Atlantic Ocean, although it is shallower by comparison.
The atmosphere of Venus has long been known to consist primarily of carbon dioxide, and the instruments of Pioneer Venus and Venera have pinpointed the proportion of carbon dioxide at 96 percent. Nitrogen constitutes more than three percent of the Venusian atmosphere. and there arc also traces of neon and several isotopes of argon.
There is some water vapor present in the Venusian cloud eover, where it has a density of 200 ppm?ten times the density of water vapor in the clear air near the surface. In the clouds the water vapor combines chemically with traces of sulphur dioxide to produce droplets of sulfuric? acid, which give the Venusian cloud cover its distinctive yellowish color.
The Venusian cloud cover is complete and unbroken. The cloud layer is roughly 15 miles thick, with its base about 30 miles above the surface of the planet, relatively higher than the thinner cloud cover on Earth. The air at the surface is probably quite clear and the air relatively still. The clouds, however, are pushed by winds with speeds up to 200 mph and circulate around the entire planet once every four Earth days, in contrast to the rotation period of Venusian ‘day’ or 243 Earth days. Electric storms are common within the clouds and lightning has been detected by both American and Soviet spacecraft.
The most notable visible feature in the Venusian atmosphere. and one that misled so many would-be mapmakers in earlier days, is the Y Feature, whose tail sometimes stretches around the planet. The feature is actually the prevailing winds in the northern and southern hemispheres as they diverge at the equator. This pattern is constantly changing, and sometimes it is seen as a reversed C. It always, however, retains an approximate north-south symmetry.
On the surface of Venus, atmospheric pressure is roughly 100 times that of the Earth. A yellowish glow like that of a smoggy sunset on Earth is all pervasive. The daytime surface temperature of 900 degrees Fahrenheit is a global constant because the carbon dioxide and sulfuric acid atmosphere and cloud cover function as an insulating blanket, trapping the heat and producing convection currents that redistribute it across the entire surface area.
Because of its proximity to the Sun, Mercury is always observed within 27 degrees of the Sun in the cast before sunrise or in the west after sunset. The closest planet to the Sun and the second smallest of the nine planets, it has been observed from Earth since prehistoric times. However, because of its size it is fainter than Venus, Mars, Jupiter and Saturn?the other planets visible to the naked eye.
Mercury has a sidereal period of just three months, the shortest of any planet. Because of this, it has the appearance from Earth of moving faster than the others, a characteristic which led the Greeks to name it Hermes, after the messenger of the gods. The Romans. in turn, called the planet Mercury after their own deities’ wing-footed messenger.
Johann Hieronymus Schroeter (1745-1816) became the first astronomer to record his observations of Mercury’s surface detail, but his drawings, like those of Giovanni Schiaparelli (1835-1910) more than a century later. were ill-defined and turned out to be inaccurate. The great American astronomer Percival Lowell (1855-1916) reported that he had observed streaks on Mercury’s surface similar to those that he and Schiaparelli had both observed on Mars. Schiaparelli had called these Martian features canali( (channels) and Lowell decided they were canals, built by intelligent life. Both astronomers agreed, however, that the streaks on Mercury’s surface were of natural origin. The major milestone in the observation of Mercury came in March 1974 when the American spacecraft Mariner 10 began a series of three flybys at a distance of about 12.000 miles, in which it was able to photograph, in great detail, objects as small as 325 feet across.
The Mariner 10 photos revealed a planet whose surface features could easily be mistaken for those on the Earth’s Moon. Like the Lunar surface, that of Mercury is pocked by thousands of craters. With the exception of the relatively smooth Caloris Basin, Mercury’s surface is characterized almost exclusively by craters, overlapping craters and craters within craters. The Lunar surface, by contrast, has more larger open areas known as maria, or seas. The Caloris Basin. which is itself pocked by hundreds of relatively smaller craters, is the only major open plain comparable to the Moon’s maria. Unlike the Lunar seas, which arc ancient lava flows, it is believed that the Caloris Basin was created by a massive, ancient impact. as is indicated by-the presence of mountains and ridges around its periphery, possibly caused by seismic waves. Other ridges and escarpments are to be seen on the surface, and are possibly due to the expansion and contraction of Mercury’s core as it cooled and shrank. Some of the cliffs produced by this effect rise as much as 6300 feet above the adjacent valley floors. There is some evidence of ancient volcanic activity on Mercury, but less than that of the Moon.
Because of Mercury’s overall density., its core is thought to be largely (70 percent) composed of iron, with the surface crust being silica rock. like that of the Earth or Lunar surfaces. Due perhaps to its slow. rotation. Mercury has a relatively weak magnetic field. despite it’ being composed mostly of iron.
Unlike the other three inner terrestrial planets. Mercury has virtually no atmosphere. Faint traces of gaseous helium form 98 percent of the ‘atmosphere,’ with the remainder being composed mostly of hydrogen. with minute traces of argon and neon also being present. The helium was probably captured from the Sun. because any gasses emanating from the interior of the planet would have long ago dissipated into space.
Mercury’s surface temperatures vary widely. The midday temperature on the side facing the Sun can be as hot as 610 degrees Fahrenheit. while at night temperatures can plummet to-346 degrees Fahrenheit because there is no atmosphere to hold the heat.
Get other Fantasy Science Fiction Books hereGet other Anne Bishop here For young Jaenelle amnesia keeps her frightening memories at bay. But with Saetan to protect her her magic–and memories–will return. Jaenelle will soon face her destiny when she remembers Daemon Saetans son who made the ultimate sacrifice for her love.In this violently passionate ‘darkly fascinating world ‘** the Blood rule: a race of witches and warlocks whose power is channeled through magical jewels. Ambitions unfurl in this second novel of The Black Jewels Trilogy as the realms dreams of a liberator have finally been made flesh… Jaenelle singled out by prophecy as the living embodiment of magic is haunted by the cruel battles the Blood have fought over her-for not all of them await her as their Savior. Nothing however can deflect her from her destiny-and the day of reckoning looms near. When her memories return. When her magic matures. When she is forced to accept her fate. On that day the dark Realms will know what it means to be ruled by Witch. CLICK HERE -Heir to the Shadows Anne Bishop Paperback at www.science-fiction-books.com.au
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Damned to Fall – By D W McDougald