Astronomy Picture of the Day
Astronomy Picture of the Day is a website provided by NASA and Michigan Technological University. According to the website, Each day a different image or photograph of our universe is featured, the photograph does not necessarily correspond to a celestial event on the exact day that it is displayed, and images are sometimes repeated. However, the pictures and descriptions often relate to current events in astronomy, the text has several hyperlinks to more pictures and websites for more information. Past images are stored in the APOD Archive, with the first image appearing on June 16,1995 and this initiative has received support from NASA, the National Science Foundation, and MTU. The images are sometimes authored by people or organizations outside NASA, when APOD began it received only 14 page views on its first day. As of 2012 it had received over a billion image views, APOD is translated into 21 languages daily. APOD was presented at a meeting of the American Astronomical Society in 1996 and its practice of using hypertext was analyzed in a paper in 2000.
It received a Scientific American Sci/Tech Web Award in 2001, in 2002, the website was featured in an interview with Nemiroff on CNN Saturday Morning News. In 2003, the two published a book titled The Universe,365 Days from Harry N. Abrams. APOD was the Featured Collection in the November 2004 issue of D-Lib Magazine, during the United States federal government shutdown of 2013, APOD continued its service on mirror sites. Dr. Robert J. Nemiroff and Dr. Jerry T
Atmosphere of Pluto
The atmosphere of Pluto is the tenuous layer of gases surrounding Pluto. It consists mainly of nitrogen, with amounts of methane and carbon monoxide. It contains layered haze, probably consisting of compounds which form from these gases due to high-energy radiation. The atmosphere of Pluto is notable for its strong and not completely clear seasonal changes caused by peculiarities of the orbital and axial rotation of Pluto. Surface pressure of the atmosphere of Pluto, measured by New Horizons in 2015, is about 1 Pa, temperature on the surface is 40 to 60 K, but it quickly grows with altitude due to methane-generated greenhouse effect. Near the altitude 30 km it reaches 110 K, and slowly decreases, Pluto is the only trans-Neptunian object with a known atmosphere. Its closest analog is the atmosphere of Triton, although in some aspects it resembles even the atmosphere of Mars, the atmosphere of Pluto has been studied since the 1980s by way of earth-based observation of occultations of stars by Pluto and spectroscopy.
In 2015, it was studied from a distance by the spacecraft New Horizons. The main component of the atmosphere of Pluto is nitrogen, content of methane, according to measurements by New Horizons, is 0. 25%. For carbon monoxide, the Earth-based estimates are 0. 025–0. 15% and 0. 05–0. 075%, under influence of high-energy cosmic radiation, these gases react to form more complex compounds, including ethane, acetylene, heavier hydrocarbons and nitriles and hydrogen cyanide. These compounds slowly precipitate on the surface, they include tholins, which are responsible for the brown color of Pluto. The most volatile compound of the atmosphere of Pluto is nitrogen, the second is carbon monoxide, the indicator of volatility is saturated vapor pressure. At temperature 40 K it is about 10 Pa for nitrogen,1 Pa for carbon monoxide and 0.001 Pa for methane and it quickly increases with temperature, and at 60 K approaches to 10000 Pa,3000 Pa and 10 Pa respectively. For heavier-than-methane hydrocarbons, ammonia, carbon dioxide and hydrogen cyanide, this pressure remains negligibly low, but actually concentration of, at least, does not depends noticeably of height and time.
But temperature dependence of volatility of methane and nitrogen suggest that concentration of methane will decrease during moving of Pluto further from the Sun, reasons of this discrepancy are unknown. It can be due to existence of separate patches of relatively clean methane ice and orbital changes of insolation results in migration of surface ices, they sublimate in some places and condensate in another. According to some estimates, it gives meter-sized changes of their thickness and this results in appreciable changes of brightness and color of Pluto. Methane and carbon monoxide, despite their low abundance, are significant for thermal structure of the atmosphere, methane is a strong heating agent and carbon monoxide is a cooling one
New Horizons is an interplanetary space probe that was launched as a part of NASAs New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory and the Southwest Research Institute, on January 19,2006, New Horizons was launched from Cape Canaveral Air Force Station directly into an Earth-and-solar escape trajectory with a speed of about 16.26 kilometers per second. After a brief encounter with asteroid 132524 APL, New Horizons proceeded to Jupiter, making its closest approach on February 28,2007, most of the post-Jupiter voyage was spent in hibernation mode to preserve on-board systems, except for brief annual checkouts. On December 6,2014, New Horizons was brought online for the Pluto encounter. On January 15,2015, the New Horizons spacecraft began its approach phase to Pluto, on July 14,2015, at 11,49 UTC, it flew 12,500 km above the surface of Pluto, making it the first spacecraft to explore the dwarf planet. On October 25,2016, at 21,48 UTC, the last of the recorded data from the Pluto flyby was received from New Horizons.
Having completed its flyby of Pluto, New Horizons has maneuvered for a flyby of Kuiper belt object 2014 MU69, expected to place on January 1,2019. Appointed as the principal investigator, Stern was described by Krimigis as the personification of the Pluto mission. New Horizons was based largely on Sterns work since Pluto 350, the New Horizons proposal was one of five that were officially submitted to NASA. It was selected as one of two finalists to be subject to a concept study, in June 2001. In November 2001, New Horizons was officially selected for funding as part of the New Frontiers program. However, the new NASA Administrator appointed by the Bush Administration, Sean OKeefe, was not supportive of New Horizons, after an intense campaign to gain support for New Horizons, the Planetary Science Decadal Survey of 2003-2013 was published in the summer of 2002. New Horizons topped the list of projects considered the highest priority among the community in the medium-size category, ahead of missions to the Moon.
Weiler stated that it was a result that administration was not going to fight, Alice Bowman became Mission Operations Manager. New Horizons is the first mission in NASAs New Frontiers mission category and more expensive than the Discovery missions, the cost of the mission is approximately $700 million over 15 years. The spacecraft was built primarily by Southwest Research Institute and the Johns Hopkins Applied Physics Laboratory, the missions principal investigator is Alan Stern of the Southwest Research Institute. After separation from the vehicle, overall control was taken by Mission Operations Center at the Applied Physics Laboratory in Howard County. The science instruments are operated at Clyde Tombaugh Science Operations Center in Boulder, New Horizons was originally planned as a voyage to the only unexplored planet in the Solar System
YouTube is an American video-sharing website headquartered in San Bruno, California. The service was created by three former PayPal employees—Chad Hurley, Steve Chen, and Jawed Karim—in February 2005, Google bought the site in November 2006 for US$1.65 billion, YouTube now operates as one of Googles subsidiaries. Unregistered users can watch videos on the site, while registered users are permitted to upload an unlimited number of videos. Videos deemed potentially offensive are available only to registered users affirming themselves to be at least 18 years old, YouTube earns advertising revenue from Google AdSense, a program which targets ads according to site content and audience. YouTube was founded by Chad Hurley, Steve Chen, and Jawed Karim, Hurley had studied design at Indiana University of Pennsylvania, and Chen and Karim studied computer science together at the University of Illinois at Urbana-Champaign. Karim could not easily find video clips of either event online and Chen said that the original idea for YouTube was a video version of an online dating service, and had been influenced by the website Hot or Not.
YouTube began as a venture capital-funded technology startup, primarily from an $11.5 million investment by Sequoia Capital between November 2005 and April 2006, YouTubes early headquarters were situated above a pizzeria and Japanese restaurant in San Mateo, California. The domain name www. youtube. com was activated on February 14,2005, the first YouTube video, titled Me at the zoo, shows co-founder Jawed Karim at the San Diego Zoo. The video was uploaded on April 23,2005, and can still be viewed on the site, YouTube offered the public a beta test of the site in May 2005. The first video to reach one million views was a Nike advertisement featuring Ronaldinho in November 2005. Following a $3.5 million investment from Sequoia Capital in November, the site grew rapidly, and in July 2006 the company announced that more than 65,000 new videos were being uploaded every day, and that the site was receiving 100 million video views per day. The site has 800 million unique users a month and it is estimated that in 2007 YouTube consumed as much bandwidth as the entire Internet in 2000.
The choice of the name www. youtube. com led to problems for a similarly named website, the sites owner, Universal Tube & Rollform Equipment, filed a lawsuit against YouTube in November 2006 after being regularly overloaded by people looking for YouTube. Universal Tube has since changed the name of its website to www. utubeonline. com, in October 2006, Google Inc. announced that it had acquired YouTube for $1.65 billion in Google stock, and the deal was finalized on November 13,2006. In March 2010, YouTube began free streaming of certain content, according to YouTube, this was the first worldwide free online broadcast of a major sporting event. On March 31,2010, the YouTube website launched a new design, with the aim of simplifying the interface, Google product manager Shiva Rajaraman commented, We really felt like we needed to step back and remove the clutter. In May 2010, YouTube videos were watched more than two times per day. This increased to three billion in May 2011, and four billion in January 2012, in February 2017, one billion hours of YouTube was watched every day
Tombaugh Regio /ˈtɒmbaʊ ˈrɛdʒi. oʊ/, nicknamed The Heart after its shape, is the largest bright surface feature of the dwarf planet Pluto. It is just north of the equator, to the northeast of Cthulhu Regio and to the northwest of Krun Macula and its western lobe, a 1000 km-wide plain of nitrogen and other ices, is named Sputnik Planitia. The eastern lobe is thought to consist of high-albedo uplands coated by nitrogen transported through the atmosphere from Sputnik Planitia, some of this nitrogen ice returns to Sputnik Planitia via glacial flow. It is named after Clyde Tombaugh, the discoverer of Pluto, Tombaugh Regio is a large, light-colored region about 1,590 km across. The two lobes of the feature are geologically distinct, the western lobe, Sputnik Planitia, is smoother than the eastern, and they are of slightly different colors. Early speculation was that the western lobe may be an impact crater filled with nitrogen snow. Bright spots within the region were initially speculated to be mountain peaks, released on 15 July 2015, revealed 3,400 m mountains made of water ice in the feature, they showed no craters in this same region.
The surface of Sputnik Planitia is divided into polygonal convection cells and is less than 10 million years old, indicating that Pluto is geologically active. The feature had been identified as a spot for six decades prior to the New Horizons flyby. Over these six decades the spot had been observed to be dimming, Tombaugh Regio was first identified in the initial image of Pluto returned after the New Horizons probe recovered from an anomaly that temporarily sent it into safe mode. NASA initially referred to it as a heart in reference to its overall shape, on 15 July 2015, the region was named Tombaugh Regio by the New Horizons team in honor of astronomer Clyde Tombaugh, the discoverer of Pluto, regio being Latin for region. Some people find the feature resembles the Disney character Pluto, the Walt Disney Company acknowledged this perceived likeness in a short animation. Geography of Pluto List of geological features on Pluto Media related to Tombaugh Regio at Wikimedia Commons
In geology, a massif is a section of a planets crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its structure while being displaced as a whole. The term is used to refer to a group of mountains formed by such a structure. In mountaineering and climbing literature, a massif is frequently used to denote the mass of an individual mountain. The massif is a structural unit of the crust than a tectonic plate and is considered the fourth largest driving force in geomorphology. The word is taken from French, where it is used to refer to a mountain mass or compact group of connected mountains forming an independent portion of a range. One of the most notable European examples of a massif is the Massif Central of the Auvergne region of France, the Face on Mars is an example of an extraterrestrial massif. Massifs may form such as with the Atlantis Massif
A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite. The International Astronomical Union currently recognizes five dwarf planets, Pluto, Makemake, another hundred or so known objects in the Solar System are suspected to be dwarf planets. Individual astronomers recognize several of these, and in August 2011 Mike Brown published a list of 390 candidate objects, Stern states that there are more than a dozen known dwarf planets. Only two of these bodies and Pluto, have observed in enough detail to demonstrate that they actually fit the IAUs definition. The IAU accepted Eris as a dwarf planet because it is more massive than Pluto and they subsequently decided that unnamed trans-Neptunian objects with an absolute magnitude brighter than +1 are to be named under the assumption that they are dwarf planets. The classification of bodies in other systems with the characteristics of dwarf planets has not been addressed. Starting in 1801, astronomers discovered Ceres and other bodies between Mars and Jupiter which were for some decades considered to be planets.
Between and around 1851, when the number of planets had reached 23, astronomers started using the asteroid for the smaller bodies. With the discovery of Pluto in 1930, most astronomers considered the Solar System to have nine planets and it was roughly one-twentieth the mass of Mercury, which made Pluto by far the smallest planet. Although it was more than ten times as massive as the largest object in the asteroid belt, Ceres. In the 1990s, astronomers began to find objects in the region of space as Pluto. Many of these shared several of Plutos key orbital characteristics, and Pluto started being seen as the largest member of a new class of objects and this led some astronomers to stop referring to Pluto as a planet. Several terms, including subplanet and planetoid, started to be used for the now known as dwarf planets. By 2005, three trans-Neptunian objects comparable in size to Pluto had been reported and it became clear that either they would have to be classified as planets, or Pluto would have to be reclassified.
Astronomers were confident that more objects as large as Pluto would be discovered, Eris was discovered in January 2005, it was thought to be slightly larger than Pluto, and some reports informally referred to it as the tenth planet. As a consequence, the became a matter of intense debate during the IAU General Assembly in August 2006. The IAUs initial draft proposal included Charon and Ceres in the list of planets, dropping Charon from the list, the new proposal removed Pluto and Eris, because they have not cleared their orbits. The IAUs final Resolution 5A preserved this three-category system for the bodies orbiting the Sun
As the nations first hour-long nightly news broadcast, the program is known for its in-depth coverage of issues and current events. Throughout their tenure and Woodruff were the first and only all-female anchor team of a nightly news program on broadcast television. The PBS NewsHour originates from WETAs studios in Arlington County, Virginia with additional facilities in San Francisco and it is a collaboration between WNET, WETA-TV, and fellow PBS member television stations KQED in San Francisco, KETC in St. Louis and WTTW in Chicago. The NewsHour Weekend is produced at the Tisch WNET studios on Lincoln Center, in 1973, Robert MacNeil and Jim Lehrer teamed up to cover the United States Senate Watergate hearings for PBS. The two earned an Emmy Award for their unprecedented gavel-to-gavel coverage, less than 1½ months on December 1,1975, the program was renamed The MacNeil/Lehrer Report and began to air on PBS stations nationwide. Most editions employed a two-anchor, two-city format, with MacNeil based in New York City, Liberty Media bought a 67% controlling equity stake in MacNeil/Lehrer Productions in 1994, but MacNeil and Lehrer retained editorial control.
Robert MacNeil retired from the program on October 20,1995, the program was renamed The NewsHour With Jim Lehrer three days on October 23. The NewsHour won a Peabody Award in 2003 for the feature report Jobless Recovery, on May 17,2006, the program underwent its first major change in presentation in years, adopting a new graphics package and a reorchestrated version of the shows theme music. The program introduced a new set and upconverted its existing graphics package to HD, on May 11,2009, PBS announced that the program would be revamped on December 7 of that year under a revised title as the PBS NewsHour. The overhaul was described by Jim Lehrer as the first phase in his move toward retirement. Lehrer formally ended his tenure as an anchor of the program in June 2011. He continued to anchor on Fridays afterward, when he usually leads the political analysis segment with Mark Shields. On August 6,2013, Gwen Ifill and Judy Woodruff were named as co-anchors, the two shared anchor duties on the Monday through Thursday editions, with Woodruff solo anchoring on Fridays due to Ifills duties as host of the political discussion program Washington Week.
Plans for an edition of PBS NewsHour had been considered as early as March 2013. MacNeil/Lehrer Productions announced in a letter to the shows staffers on October 8,2013, the transfer was approved by the WETA board of trustees on June 17,2014, and took effect on July 1. At that time, production of the program was taken over by NewsHour Productions, LLC, WETA acquired MacNeil/Lehrer Productions archives and projects, though not the companys name. PBS NewsHour Weekend was not affected by the transfer and continues to be produced by WNET. The program is notable for being shown on public television, as such, there are no interruptions during the program to run advertisements
Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond Neptune. It was the first Kuiper belt object to be discovered, Pluto was discovered by Clyde Tombaugh in 1930 and was originally considered to be the ninth planet from the Sun. After 1992, its planethood was questioned following the discovery of objects of similar size in the Kuiper belt. In 2005, which is 27% more massive than Pluto, was discovered and this led the International Astronomical Union to define the term planet formally in 2006, during their 26th General Assembly. That definition excluded Pluto and reclassified it as a dwarf planet, Pluto is the largest and second-most-massive known dwarf planet in the Solar System and the ninth-largest and tenth-most-massive known object directly orbiting the Sun. It is the largest known trans-Neptunian object by volume but is less massive than Eris, like other Kuiper belt objects, Pluto is primarily made of ice and rock and is relatively small—about one-sixth the mass of the Moon and one-third its volume.
It has an eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, light from the Sun takes about 5.5 hours to reach Pluto at its average distance. Pluto has five moons, Styx, Kerberos. Pluto and Charon are sometimes considered a system because the barycenter of their orbits does not lie within either body. The IAU has not formalized a definition for binary dwarf planets, on July 14,2015, the New Horizons spacecraft became the first spacecraft to fly by Pluto. During its brief flyby, New Horizons made detailed measurements and observations of Pluto, on October 25,2016, at 05,48 pm ET, the last bit of data was received from New Horizons from its close encounter with Pluto on July 14,2015. In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the position of the then-undiscovered planet Neptune after analysing perturbations in the orbit of Uranus. Subsequent observations of Neptune in the late 19th century led astronomers to speculate that Uranuss orbit was being disturbed by another planet besides Neptune, by 1909, Lowell and William H.
Pickering had suggested several possible celestial coordinates for such a planet. Lowell and his observatory conducted his search until his death in 1916, unknown to Lowell, his surveys had captured two faint images of Pluto on March 19 and April 7,1915, but they were not recognized for what they were. There are fourteen other known prediscovery observations, with the oldest made by the Yerkes Observatory on August 20,1909. Percivals widow, Constance Lowell, entered into a legal battle with the Lowell Observatory over her late husbands legacy. Tombaughs task was to image the night sky in pairs of photographs, examine each pair
Sputnik Planitia /ˈspʌtnɪk pləˈnɪʃiə/, originally Sputnik Planum, is a high-albedo ice-covered basin on Pluto, about 1,050 by 800 km in size. It lies mostly in the hemisphere, but extends across the equator. Much of it has a surface of irregular polygons separated by troughs, the polygons are on average about 33 km across. In some cases troughs are populated by blocky mountains or hills, Sputnik Planitia constitutes the western lobe of the heart-shaped Tombaugh Regio. There appear to be wind streaks on the surface evidence of sublimation. The dark streaks are a few kilometers long and all aligned in the same direction, the basin contains pits that have possibly formed by sublimation. Sputnik Planitia is named after Earths first artificial satellite, the planitia has no craters that were detectable by New Horizons, leading to the conclusion that its surface must be less than 10 million years old. The ice composing the basin is thought to consist primarily of ice, with smaller fractions of carbon monoxide and methane ice.
At Plutos ambient temperature of 38 K, nitrogen and carbon monoxide ices are denser and much less rigid water ice, making glacial-like flows possible. Sputnik Planitia may have originated as a basin that subsequently collected volatile ices. Alternatively, it has suggested that the accumulation of ices in this location depressed the surface there. The accumulation of several kilometers of ice in the basin was in part a consequence of its higher surface pressure. The positive temperature gradient of Plutos atmosphere contributes to making a topographic depression a cold trap, a high seasonal thermal inertia of Plutos surface is an important driver of deposition of nitrogen ice at low latitudes. These latitudes receive less insolation than Plutos polar regions due to its high obliquity. However, other effects of an event could have contributed to such an anomaly. A positive gravity anomaly could have caused polar wander, reorienting the spin axis of Pluto to put the planitia near the Pluto-Charon tidal axis, Sputnik Planitia is presently close to the anti-Charon point on Pluto, a result that has less than a 5% probability of arising by chance.
Gradual freezing of such an ocean, in combination with polar wander, convection cells have about 100 m of vertical relief, with the highest points being at their centers. Modeling of nitrogen ice convection cells suggests a depth of one tenth their width, or 3–4 km for most of the planitia
Mount Everest, known in Nepal as Sagarmāthā and in China as Chomolungma/珠穆朗玛峰, is Earths highest mountain. Its peak is 8,848 metres above sea level, Mount Everest is in the Mahalangur Range. The international border between China and Nepal runs across Everests summit point and its massif includes neighbouring peaks Lhotse,8,516 m, Nuptse,7,855 m, and Changtse,7,580 m. In 1856, the Great Trigonometrical Survey of India established the first published height of Everest, known as Peak XV, at 8,840 m. The current official height of 8,848 m as recognised by China and Nepal was established by a 1955 Indian survey, in 2005, China remeasured the height of the mountain and got a result of 8844.43 m. An argument regarding the height between China and Nepal lasted five years from 2005 to 2010, China argued it should be measured by its rock height which is 8,844 m but Nepal said it should be measured by its snow height 8,848 m. In 2010, an agreement was reached by both sides that the height of Everest is 8,848 m and Nepal recognises Chinas claim that the rock height of Everest is 8,844 m.
In 1865, Everest was given its official English name by the Royal Geographical Society upon a recommendation by Andrew Waugh, the British Surveyor General of India. As there appeared to be several different local names, Waugh chose to name the mountain after his predecessor in the post, Sir George Everest, Mount Everest attracts many climbers, some of them highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal and the other from the north in Tibet, as of 2016 there are well over 200 corpses on the mountain, with some of them even serving as landmarks. The first recorded efforts to reach Everests summit were made by British mountaineers, with Nepal not allowing foreigners into the country at the time, the British made several attempts on the north ridge route from the Tibetan side. Tragedy struck on the descent from the North Col when seven porters were killed in an avalanche. They had been spotted high on the mountain that day but disappeared in the clouds, never to be seen again, Tenzing Norgay and Edmund Hillary made the first official ascent of Everest in 1953 using the southeast ridge route.
Tenzing had reached 8,595 m the previous year as a member of the 1952 Swiss expedition, the Chinese mountaineering team of Wang Fuzhou, and Qu Yinhua made the first reported ascent of the peak from the north ridge on 25 May 1960. In 1802, the British began the Great Trigonometric Survey of India to fix the locations, starting in southern India, the survey teams moved northward using giant theodolites, each weighing 500 kg and requiring 12 men to carry, to measure heights as accurately as possible. They reached the Himalayan foothills by the 1830s, but Nepal was unwilling to allow the British to enter the country due to suspicions of political aggression, several requests by the surveyors to enter Nepal were turned down. The British were forced to continue their observations from Terai, a region south of Nepal which is parallel to the Himalayas, conditions in Terai were difficult because of torrential rains and malaria. Three survey officers died from malaria while two others had to retire because of failing health, nonetheless, in 1847, the British continued the survey and began detailed observations of the Himalayan peaks from observation stations up to 240 km distant