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Globular Cluster M13
Messier 13 or M13, also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of several hundred thousand stars in the constellation of Hercules. Discovery and visibility M13 was discovered by Edmond Halley in 1714, and cataloged by Charles Messier on June 1, 1764, into his list of objects not to mistake for comets; Messier's list, including Messier 13, eventually became known as the Messier Catalog. About one third of the way from Vega to Arcturus, four bright stars in Herculēs form the Keystone asterism, the broad torso of the hero. M13 can be seen in this asterism of the way north ( by west) from Zeta to Eta Herculis. Although only telescopes with great light-gathering capability fully resolve the stars of the cluster, M13 may be visible to the naked eye depending on circumstances. With a low-power telescope, Messier 13 looks like a comet or fuzzy patch. The cluster is visible throughout the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Messier 13
Messier 13 or M13, also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of several hundred thousand stars in the constellation of Hercules. Discovery and visibility M13 was discovered by Edmond Halley in 1714, and cataloged by Charles Messier on June 1, 1764, into his list of objects not to mistake for comets; Messier's list, including Messier 13, eventually became known as the Messier Catalog. About one third of the way from Vega to Arcturus, four bright stars in Herculēs form the Keystone asterism, the broad torso of the hero. M13 can be seen in this asterism of the way north ( by west) from Zeta to Eta Herculis. Although only telescopes with great light-gathering capability fully resolve the stars of the cluster, M13 may be visible to the naked eye depending on circumstances. With a low-power telescope, Messier 13 looks like a comet or fuzzy patch. The cluster is visible throughout the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to Earth's axial tilt of 23.439281°, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation. Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to the Coriolis e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science Fiction
Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, extraterrestrial life, sentient artificial intelligence, cybernetics, certain forms of immortality (like mind uploading), and the singularity. Science fiction predicted several existing inventions, such as the atomic bomb, robots, and borazon, whose names entirely match their fictional predecessors. In addition, science fiction might serve as an outlet to facilitate future scientific and technological innovations. Science fiction can trace its roots to ancient mythology. It is also related to fantasy, horror, and superhero fiction and contains many subgenres. Its exact definition has long been disputed among authors, critics, scholars, and readers. Science fiction, in literature, film, television, and other media, has beco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. Following two breaks in cables supporting the receiver platform in mid-2020, the NSF decommissioned the telescope. A partial collapse of the telescope occurred on December 1, 2020, before controlled demolition could be conducted. In 2022, the NSF announced the telescope will not be rebuilt, with an educational fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Message
The Arecibo message is an interstellar radio message carrying basic information about humanity and Earth that was sent to the globular cluster Messier 13 in 1974. It was meant as a demonstration of human technological achievement, rather than a real attempt to enter into a conversation with extraterrestrials. It has been noted that the low resolution of the image makes it infeasible for any extraterrestrial recipients to attach the intended meaning to most of its elements. The message was Broadcasting, broadcast into space a single time via frequency modulation, frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo Telescope in Puerto Rico on 16 November 1974. The message was aimed at the current location of M13, about 25,000 light years from Earth, because M13 was a large and relatively close collection of stars that was available in the sky at the time and place of the ceremony. When correctly translated into graphics, characters, and spaces, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Straggler
A blue straggler is a main-sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hert ... star in an open cluster, open or globular cluster that is more luminosity, luminous and stellar classification, bluer than stars at the main sequence turnoff point for the cluster. Blue stragglers were first discovered by Allan Sandage in 1953 while performing photometry (astronomy), photometry of the stars in the globular cluster Messier 3, M3. Standard theories of stellar evolution hold that the position of a star on the Hertzsprung–Russell diagram should be determined almost entirely by the initial mass of the star and its age. In a cluster, stars all formed at approximately the same time, and thus in an H–R diagram for a cluster, all stars should lie along a clearly defined curve set by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: * Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. * Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol. Of the modern astronomers, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or lower. The appearance of the red giant is from yellow-white to reddish-orange, including the spectral types K and M, sometimes G, but also class S stars and most carbon stars. Red giants vary in the way by which they generate energy: * most common red giants are stars on the red-giant branch (RGB) that are still fusing hydrogen into helium in a shell surrounding an inert helium core * red-clump stars in the cool half of the horizontal branch, fusing helium into carbon in their cores via the triple-alpha process * asymptotic-giant-branch (AGB) stars with a helium burning shell outside a degenerate carbon–oxygen core, and a hydrogen-burning shell just beyond that. Many of the well-known bright stars are red giants because they are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for the diameter of a sphere. In more modern usage, the length d of a diameter is also called the diameter. In this sense one speaks of diameter rather than diameter (which refers to the line segment itself), because all diameters of a circle or sphere have the same length, this being twice the radius r. :d = 2r \qquad\text\qquad r = \frac. For a convex shape in the plane, the diameter is defined to be the largest distance that can be formed between two opposite parallel lines tangent to its boundary, and the is often defined to be the smallest such distance. Both quantities can be calculated efficiently using rotating calipers. For a curve of constant width such as the Reuleaux triangle, the width and diameter are the same because all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word "year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. Defini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 6207
NGC 6207 is a spiral galaxy located in the constellation Hercules. It is designated as SA(s)c in the galaxy morphological classification scheme and was discovered by William Herschel on 16 May 1787. NGC 6207 is located at about 30 million light-years from earth. It is located near the globular cluster Messier 13. See also * List of NGC objects (6001–7000) This is a list of NGC objects 6001–7000 from the New General Catalogue (NGC). The astronomical catalog An astronomical catalog or catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a comm ... References External links * Unbarred spiral galaxies Hercules (constellation) 6207 10521 58827 {{Spiral-galaxy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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