The Bortle scale on which areas away from human habitation unsurprisingly receive high ratings and which is of particular interest to amateur astronomers is concerned with what property?
"in ""Sky and Telescope"" magazine in 2001. The scale ranges from 1 (extremely dark rural area or national park, usually at high elevation, low humidity, and low wind) to 9 (urban inner city). 4. ^ 1974 Comet Medalist, ASP Journal, 1974 5. ^ AAVSO Journal, Report on the 1983 Fall General Meeting 6. ^ N.E.R.A.L. website 7. ^ AAVSO Observer Records, 2016 John E. Bortle John E. Bortle is an American amateur astronomer. He is best known for creating the Bortle scale to quantify the darkness of the night sky. Bortle has made a special study of comets. He has"
"Bortle scale The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. John E. Bortle created the scale and published it in the February 2001 edition of ""Sky & Telescope"" magazine to help amateur astronomers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites. The scale ranges from Class 1, the darkest skies available on Earth, through Class 9, inner-city skies. It gives several criteria for each level beyond naked-eye"
"limiting magnitude (NELM). The accuracy and utility of the scale have been questioned in recent research. The table below summarizes Bortle's descriptions of the classes. Bortle scale The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. John E. Bortle created the scale and published it in the February 2001 edition of ""Sky & Telescope"" magazine to help amateur astronomers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites. The"
"attempts to quantify the subjective brightness and suitability for astronomy of the sky in different environments. On his use of the scale, which was invented in 2001, Bogard has said, ""one of the reasons why identifying different depths of darkness is so important is that we don’t recognize that we’re losing it, unless we have a name to recognize it by."" Bogard begins at a Bortle level 9 environment, by the Luxor Sky Beam, the brightest spotlight on Earth, located on the Las Vegas Strip. He explores the nighttime landscapes of London and Paris, and examines the planning, or lack"
"swirling stratospheric winds high up and calm air at ground level combine to make it a place for viewing into space that is three times clearer than any other location on Earth. Researchers on the project suggested that photographs taken through a telescope at Ridge A could be nearly as good as those taken by the Hubble Space Telescope. Despite the difficult conditions on Antarctica and the remote location of Ridge A, construction costs for an observatory there that could match the Hubble telescope could be built at a fraction of the cost of sending Hubble into space. For several"
"Sky Reserve by the International Dark-Sky Association, one of only four such reserves around the world. The area has a Bortle Scale of 2. There are 5 large telescopes on the mountain that are in regular use. There is also a cafe and night-tours run by tourist operators, Earth and Sky. There is accommodation for visiting researchers within the 1.0m building. A Superintendent lives on the mountain. Opened in 2004 December, this telescope was built by Japanese astronomers and is dedicated to the MOA project. It is a 1.8m prime focus reflector. The MOA telescope is the largest telescope in"
"frequency ranges which are outside the optical window and the radio window, the only two wavelength ranges of the electromagnetic spectrum that are not severely attenuated by the atmosphere. For example, X-ray astronomy is nearly impossible when done from Earth, and has reached its current importance in astronomy only due to orbiting X-ray telescopes such as the Chandra observatory and the XMM-Newton observatory. Infrared and ultraviolet are also largely blocked. However, all these advantages do come with a price. Space telescopes are much more expensive to build than ground-based telescopes. Due to their location, space telescopes are also extremely difficult"
"are threatened by civilization. In particular, light pollution is introduced by nearby Las Vegas. The darkest skies are, in general, located in the northwest of the park. The northwestern area of the park, including sites such as Ubehebe Crater, is a Bortle class 1 or ""excellent dark sky"" site. The Andromeda Galaxy and the Triangulum Galaxy are visible to the unaided eye under these conditions, and the Milky Way casts shadows; optical phenomenon such as zodiacal light or ""false dawn"" and gegenschein are also visible to the unaided eye under these conditions. Most southern regions of the park are Bortle"
"most distant of the photographs was taken at an altitude of 89,879 km, the closest at an altitude of 7,546 km. Resolution, therefore, varies widely but ranges from about 1.5 to 2.0 km over most of the area. A wide range (more than 50 deg) of both viewing and solar illumination angles precludes a high degree of mapping consistency. The easternmost 10° of the quadrangle is beyond the evening terminator. A low angle of solar illumination and a high viewing angle make possible discrimination of topographic detail near the terminator. Higher angles of solar illumination and lower viewing angles make"
"Man-made structures visible from space Man-made structures visible from earth orbit without magnification (by mechanical aids such as a camera or binoculars) include highways, dams, and cities. Recently made world's tallest statue Statue of Unity in India is not visible from space without magnification. Also the Great Wall of China, is not visible from low Earth orbit without magnifying instrument and even then only under perfect conditions, but not from the Moon. Part of the problem in authoritatively answering questions about visibility from space is that such questions are often very vaguely framed: askers frequently do not precisely define how"
"resolution. The principal limitation on infrared sensitivity from ground-based telescopes is the Earth's atmosphere. Water vapor absorbs a significant amount of infrared radiation, and the atmosphere itself emits at infrared wavelengths. For this reason, most infrared telescopes are built in very dry places at high altitude, so that they are above most of the water vapor in the atmosphere. Suitable locations on Earth include Mauna Kea Observatory at 4205 meters above sea level, the Paranal Observatory at 2635 meters in Chile and regions of high altitude ice-desert such as Dome C in Antarctic. Even at high altitudes, the transparency of"
"above the atmosphere of our planet. Another advantage of space-based telescopes is that, because of their location above the Earth's atmosphere, their images are free from the effects of atmospheric turbulence that plague ground-based observations. As a result, the angular resolution of space telescopes such as the Hubble Space Telescope is often much smaller than a ground-based telescope with a similar aperture. However, all these advantages do come with a price. Space telescopes are much more expensive to build than ground-based telescopes. Due to their location, space telescopes are also extremely difficult to maintain. The Hubble Space Telescope was serviced"
"Bortle Dark-Sky Scale, is bright enough to be viewed with the naked eye from dark suburban skies. The orbital motion of the Earth causes this star to undergo an annual parallax shift of 17.77 milliarcseconds. From this measurement, the distance to this star can be determined, yielding an estimate of approximately 184 light years with a 2% margin of error. The magnitude of the star is diminished by 0.09 from the extinction caused by interstellar gas and dust. The spectrum of this star matches a stellar classification of G9 III, where the G9 means that it belongs to the category"
"No topography is visible on Mars from Earth. The bright areas and dark markings seen through a telescope are albedo features. The bright, red-ochre areas are locations where fine dust covers the surface. Bright areas (excluding the polar caps and clouds) include Hellas, Tharsis, and Arabia Terra. The dark gray markings represent areas that the wind has swept clean of dust, leaving behind the lower layer of dark, rocky material. Dark markings are most distinct in a broad belt from 0° to 40° S latitude. However, the most prominent dark marking, Syrtis Major Planum, is in the northern hemisphere. The"
"ultraviolet, visible, and near infrared spectra. Hubble's orbit outside the distortion of Earth's atmosphere allows it to take extremely high-resolution images, with substantially lower background light than ground-based telescopes. Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe. The HST was built by the United States space agency NASA, with contributions from the European Space Agency. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting"
"night skies, which are far away from and largely free of the light pollution typical in the urban areas. The park's elevation and dry desert air, along with the relatively stable atmosphere in the region, often make for excellent seeing conditions. On clear nights around new moon, the sky darkness of Joshua Tree is rated a Class 2–4 on the Bortle scale. This ranges from an ""average dark sky"" (Class 2) in the easternmost region of the park to a sky quality typical of a rural/suburban transition (Class 4) in the western regions near Palm Springs. In the easternmost regions"
"dark skies, a large percentage of clear nights per year, dry air, and are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical ""seeing"". Sites that meet the above criteria for modern observatories include the southwestern United States, Hawaii, Canary Islands, the Andes, and high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its"
"popularity, as it focusses on differential absorption features and omits broad-band absorption such as aerosol extinction and extinction due to rayleigh scattering. This method is applied to ground-based, air-borne and satellite based measurements. Some ground-based methods provide the possibility to retrieve tropospheric and stratospheric trace gas profiles. Astronomical spectroscopy is a particularly significant type of remote spectral sensing. In this case, the objects and samples of interest are so distant from earth that electromagnetic radiation is the only means available to measure them. Astronomical spectra contain both absorption and emission spectral information. Absorption spectroscopy has been particularly important for understanding"
"population centres. There are only a handful of such sites identified, they include Mauna Kea (Hawaii, United States), the Llano de Chajnantor Observatory on the Atacama Plateau (Chile), the South Pole, and Hanle in India (the Himalayan site of the Indian Astronomical Observatory). Comparisons show that all four sites are excellent for submillimetre astronomy, and of these sites Mauna Kea is the most established and arguably the most accessible. There has been some recent interest in high-altitude Arctic sites, particularly Summit Station in Greenland where the PWV (precipitable water vapor) measure is always better than at Mauna Kea (however Mauna"
"elevation angle of 38°. Other advantages include the very low infrared sky emission, the high percentage of cloud-free time and the low aerosol and dust content of the atmosphere. The median seeing measured with a DIMM Differential Image Motion Monitor placed on top of an 8.5 m high tower is 1.3 ± 0.8 arcseconds. This is significantly worse than most major observatory sites, but similar to other observatories in Antarctica. However, Lawrence et al. consider other features of the site and conclude that ""Dome C is the best ground-based site to develop a new astronomical observatory"". Note however that this"
"Ladakh. Hanle is home to the Indian Astronomical Observatory. The location of the village and the observatory are highly sensitive due to the close proximity of the Tibetan / Chinese border. Special permission is needed to visit either by the Indian Government. India set up the Himalayan Chandra Telescope, a 2m gamma ray telescope. Once complete the Major Atmospheric Cerenkov Experiment Telescope gamma ray telescope under construction there will be the world's largest telescope at the highest altitude and the second largest gamma ray telescope in the world. Fukche airport is 24 km away, and Ukdungle town is close by."
"object. It also lies near the ecliptic, which causes the Moon, and some of the planets to occasionally pass through it for brief periods of time. The constellation is the location of the field studied by the COSMOS project, undertaken by the Hubble Space Telescope. Sextans B is a fairly bright dwarf irregular galaxy at magnitude 6.6, 4.3 million light-years from Earth. It is part of the Local Group of galaxies. CL J1001+0220 is as of 2016 the most distant known galaxy cluster at redshift z=2.506, 11.1 billion light-years from Earth. In June 2015, astronomers reported evidence for Population III"
"supernovae, which explode unexpectedly, or near-earth asteroids that may be discovered shortly before their closest approach to the Earth. Although the observers are usually remote, the telescope operator is at the summit to ensure the safety of the facility, assist the observer, and troubleshoot problems that may arise during the night. NASA's Infrared Telescope Facility (IRTF) also made observations of P/2016 BA14, which is a comet that came within about 9 lunar distances of Earth in 2016. Dedicated infrared telescopes require a high and dry location, special instrumentation, and similar high-quality mirrors and optics as for visible wavelength observations. Other"
"comets. They remain a fundamental tool for the exploration of outer space, as well as observation of the Earth. In August 2012, Voyager 1 became the first man-made object to leave the Solar System and enter interstellar space. The absence of air makes outer space an ideal location for astronomy at all wavelengths of the electromagnetic spectrum. This is evidenced by the spectacular pictures sent back by the Hubble Space Telescope, allowing light from more than 13 billion years ago—almost to the time of the Big Bang—to be observed. However, not every location in space is ideal for a telescope."
"above sea level. There is no basement but the rock ballast in the bottom floor and octagonal design have kept the structure steady during storms. The observatory's 'lantern' (cupola) included a P & J Dollond Achromatic Refracting Telescope, which could identify ships 30 miles (48 km) to sea. That telescope disappeared from the observatory in 1939. The observatory has been renovated numerous times over the years, including a Works Progress Administration renovation in 1939. It was most recently renovated from 1998-2000 to repair damage from moisture and powderpost beetles. This renovation won a 2001 National Preservation Honor Award from the"
"the Hubble Space Telescope at its highest point and 20 times at its lowest. In comparison, the average distance from Earth to the Moon is . As of 2018, the satellite has a much more stable orbit with a perigee of and an apogee of , with its orbit no longer intersecting the Moon's orbit and being stable for possibly hundreds or even thousands of years. The main scientific goal of the mission is the study of astronomical objects with an angular resolution up to a few millionths of an arcsecond. This is accomplished by using the satellite in conjunction"
"about east of Pitcairn Island (the nearest human habitat) and is the most remote inhabited spot on Earth. The park is triangular in shape and has a length of and a width of . It is home to an extinct megalithic culture which is seen in the form of edifices of huge statues called ""moai"" made out of volcanic rocks. The topography includes volcanoes and a rugged coastline. Its elevation varies from sea level to . It has fresh water lakes, volcanic craters and a coastline which is subject to erosion. The park experiences a warm sub-tropical climate with southeast"
"the Five-hundred-meter Aperture Spherical Telescope (FAST), also located in China, can both observe frequencies in the ""water hole"" that has traditionally been favored by scientists engaged in the Search for Extraterrestrial Intelligence (SETI), meaning that each observatory could provide follow-up observations of putative signals from extraterrestrials detected in this quiet part of the radio spectrum at the other observatory. The radio telescope site selection team considered 48 candidate locations throughout Xinjiang. The chosen site for the facility is in the foothills of the Tian Shan mountains, near Shihezi village, Banjiegou Town, about 46 km (straight-line distance) south-south-east of the Qitai"
"Helmut Ullrich Astronomical Observatory The Helmut Ullrich Astronomical Observatory is an observatory situated on Col Drusciè, a mountain peak in the Dolomites located within Cortina d'Ampezzo, Italy. The observatory sits at an elevation of above sea level and includes two domes, with a 20"" Newtonian telescope and an 11"" Schmidt–Cassegrain telescope inside. The observatory hosts a remote control system called ""Sky on the Web"", which allows users to control the operation of the observatory remotely, including telescope pointing, image taking and processing, image downloading on one's home PC, weather alerts. The amateur astronomers that manage the observatory are mainly involved"
"La Silla is located far from sources of light pollution and, like the Paranal Observatory, home to the Very Large Telescope, it has one of the darkest night skies on the Earth. Following the decision in 1963 to approve Chile as the site for the ESO observatory, scouting parties were sent to various locations to assess their suitability. The site that was decided upon was La Silla in the southern part of the Atacama desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres. Besides being government property, it had the added benefits of being"
"stars to be observed, even when the Sun is at its highest possible elevation angle of 38°. The good viewing is due to very low infrared sky emission, extremely low humidity, a high percentage of cloud-free time, low atmospheric aerosol and dust content, and an absence of light pollution other than auroras and moonlight. This location was a serious candidate for the ESO's E-ELT project. However, sky coverage is less than at lower latitude locations as northern celestial hemisphere objects never rise or are too low above the horizon. Writing in the Proceedings of the Astronomical Society of the Pacific"
"location is also suitable for an array of optical telescopes, similar to the Very Large Telescope in Chile. To date, there has been no ground exploration of the far side. Scientists have estimated that the highest concentrations of helium-3 can be found in the maria on the far side, as well as near side areas containing concentrations of the titanium-based mineral ilmenite. On the near side the Earth and its magnetic field partially shields the surface from the solar wind during each orbit. But the far side is fully exposed, and thus should receive a somewhat greater proportion of the"
"generally can see from space would reflect altitudes that manned spacecraft typically orbit the Earth at—often several hundreds of kilometres. There are major differences in visibility from just above the Kármán line (100 km/62 miles) and the ISS orbit (394 km/245 miles), for example. From US Space Shuttles, which typically orbited at around , cities were easily distinguishable from surrounding countryside. Using binoculars, astronauts could even see roads, dams, harbors, even large vehicles such as ships and planes. At night, cities are also easily visible from the higher orbit of the ISS. Metropolitan areas are clear at night, particularly in"