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Topic Review
Astronomy in the Medieval Islamic World
Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took place in the Middle East, Central Asia, Al-Andalus, and North Africa, and later in the Far East and India. It closely parallels the genesis of other Islamic sciences in its assimilation of foreign material and the amalgamation of the disparate elements of that material to create a science with Islamic characteristics. These included Greek, Sassanid, and Indian works in particular, which were translated and built upon. Islamic astronomy played a significant role in the revival of Byzantine and European astronomy following the loss of knowledge during the early medieval period, notably with the production of Latin translations of Arabic works during the 12th century. Islamic astronomy also had an influence on Chinese astronomy and Malian astronomy. A significant number of stars in the sky, such as Aldebaran, Altair and Deneb, and astronomical terms such as alidade, azimuth, and nadir, are still referred to by their Arabic names. A large corpus of literature from Islamic astronomy remains today, numbering approximately 10,000 manuscripts scattered throughout the world, many of which have not been read or catalogued. Even so, a reasonably accurate picture of Islamic activity in the field of astronomy can be reconstructed.
  • 12.8K
  • 24 Nov 2022
Topic Review
Zodiac
The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets are within the belt of the zodiac. In Western astrology, and formerly astronomy, the zodiac is divided into twelve signs, each occupying 30° of celestial longitude and roughly corresponding to the following star constellations: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. These astrological signs form a celestial coordinate system, or more specifically an ecliptic coordinate system, which takes the ecliptic as the origin of latitude and the Sun's position at vernal equinox as the origin of longitude.
  • 9.0K
  • 31 Oct 2022
Topic Review
Venusians
In science fiction and in the beliefs of ufology, a Venusian (/vɪˈnjuːʒən, -ʃən/) or Venerian is a native inhabitant of the planet Venus. Many science fiction writers have imagined what extraterrestrial life on Venus might be like.
  • 6.5K
  • 21 Oct 2022
Topic Review
Venus in Culture
Venus, as one of the brightest objects in the sky, has been known since prehistoric times and has been a major fixture in human culture for as long as records have existed. As such, it has a prominent position in human culture, religion, and myth. It has been made sacred to gods of many cultures, and has been a prime inspiration for writers and poets as the morning star and evening star.
  • 6.0K
  • 14 Nov 2022
Topic Review
List of Asteroids in Astrology
Asteroids are relatively new to astrology, having only been discovered in the 19th century. However, some of them (especially the largest of them), are believed by some astrologers to influence human affairs. Still though, they are often ignored within mainstream systems of astrology, especially in more traditional astrology systems like Vedic astrology or Hellenistic astrology. Their use has become significant to a few Western astrologers yet still only a minority of astrologers use the asteroids in chart interpretation.
  • 5.3K
  • 22 Nov 2022
Topic Review
Solar Storm of 1859
The solar storm of 1859 (also known as the Carrington Event) was a powerful geomagnetic storm during solar cycle 10 (1855–1867). A solar coronal mass ejection (CME) hit Earth's magnetosphere and induced the largest geomagnetic storm on record, September 1–2, 1859. The associated "white light flare" in the solar photosphere was observed and recorded by British astronomers Richard C. Carrington (1826–1875) and Richard Hodgson (1804–1872). The storm caused strong auroral displays and wrought havoc with telegraph systems. The now-standard unique IAU identifier for this flare is SOL1859-09-01. A solar storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid. The solar storm of 2012 was of similar magnitude, but it passed Earth's orbit without striking the planet, missing by nine days.
  • 4.6K
  • 20 Oct 2022
Topic Review
Bṛhaspati
Bṛhaspati (Sanskrit: बृहस्पति; meaning spati of briha, the spirit of vastness of the universe written as Brihaspati) is an Indian name, and refers to different mythical figures depending on the age of the text. In ancient Hindu literature Brihaspati is a Vedic era sage who counsels the gods, while in some medieval texts the word refers to the largest planet of the solar system, Jupiter. He taught Bhishma the duties of a king which he later taught it to Vidura.
  • 4.4K
  • 18 Oct 2022
Topic Review
Cydonia (Region of Mars)
Cydonia (/sɪˈdoʊniə/, /saɪˈdoʊniə/) is a region on the planet Mars that has attracted both scientific and popular interest. The name originally referred to the albedo feature (distinctively coloured area) that was visible from Earthbound telescopes. The area borders plains of Acidalia Planitia and the Arabia Terra highlands. The area includes the regions: "Cydonia Mensae", an area of flat-topped mesa-like features, "Cydonia Colles", a region of small hills or knobs, and "Cydonia Labyrinthus", a complex of intersecting valleys. As with other albedo features on Mars, the name Cydonia was drawn from classical antiquity, in this case from Kydonia, a historic polis (or "city-state") on the island of Crete. Cydonia contains the "Face on Mars", located about halfway between Arandas Crater and Bamberg Crater.
  • 4.4K
  • 25 Oct 2022
Topic Review
Red Supergiant Star
Red supergiants (RSGs) are stars with a supergiant luminosity class (Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.
  • 4.1K
  • 18 Nov 2022
Topic Review
SpaceX Mars Transportation Infrastructure
Elon Musk and SpaceX have proposed the development of Mars transportation infrastructure in order to facilitate the eventual colonization of Mars. The mission architecture includes fully reusable launch vehicles, human-rated spacecraft, on-orbit propellant tankers, rapid-turnaround launch/landing mounts, and local production of rocket fuel on Mars via in situ resource utilization (ISRU). SpaceX's aspirational goal since 2017 has been to land the first humans on Mars by 2024. A key element of the infrastructure is planned to be the SpaceX Starship, a fully reusable space vehicle under development since 2018. To achieve a large payload, the spacecraft would first enter Earth orbit, where it is expected to be refueled before it departs to Mars. After landing on Mars, the spacecraft would be loaded with locally-produced propellants to return to Earth. The expected payload for the Starship/Super Heavy is to inject between 100–150 tonnes (220,000–330,000 lb) to Mars. SpaceX intends to concentrate its resources on the transportation part of the Mars colonization project, including the design of a propellant plant based on the Sabatier process that will be deployed on Mars to synthesize methane and liquid oxygen as rocket propellants from the local supply of atmospheric carbon dioxide and ground-accessible water ice. However, Musk has advocated since 2016 a larger set of long-term Mars settlement objectives, going far beyond what SpaceX projects to build; any successful colonization would ultimately involve many more economic actors—whether individuals, companies, or governments—to facilitate the growth of the human presence on Mars over many decades.
  • 3.9K
  • 21 Nov 2022
Topic Review
Libra
The constellation Libra, known as the Scales or the Balance, is one of the 12 zodiac constellations representing an inanimate object. It is located in the southern sky and is associated with justice and balance. Libra is depicted as scales held by the Greek goddess of justice, Astraea, and is the only zodiac constellation named after an object rather than an animal or character from mythology.
  • 3.4K
  • 15 Mar 2024
Topic Review
Phosphorus (Morning Star)
Phosphorus (Greek Φωσφόρος Phōsphoros) is the Morning Star, the planet Venus in its morning appearance. Φαοσφόρος (Phaosphoros) and Φαεσφόρος (Phaesphoros) are forms of the same name in some Greek dialects. This celestial object was named when stars and planets were not always distinguished with modern precision. Another Greek name for the Morning Star is Heosphoros (Greek Ἑωσφόρος Heōsphoros), meaning "Dawn-Bringer". The form Eosphorus is sometimes met in English, as if from Ἠωσφόρος (Ēōsphoros), which is not actually found in Greek literature, but would be the form that Ἑωσφόρος would have in some dialects. As an adjective, the Greek word φωσφόρος is applied in the sense of "light-bringing" to, for instance, the dawn, the god Dionysos, pine torches, the day; and in the sense of "torch-bearing" as an epithet of several god and goddesses, especially Hecate but also of Artemis/Diana and Hephaestus. The Latin word lucifer, corresponding to Greek φωσφόρος, was used as a name for the morning star and thus appeared in the Vulgate translation of the Hebrew word הֵילֵל (helel), meaning Venus as the brilliant, bright or shining one, in Isaiah 14:12, where the Septuagint Greek version uses, not φωσφόρος, but ἑωσφόρος. As a translation of the same Hebrew word the King James Version gave "Lucifer", a name often misunderstood as a reference to Satan. Modern translations of the same passage render the Hebrew word instead as "morning star", "daystar", "shining one" or "shining star". In Revelation 22:16, Jesus is referred to as the morning star, but not as lucifer in Latin, nor as φωσφόρος in the original Greek text, which instead has ὁ ἀστὴρ ὁ λαμπρὸς ὁ πρωϊνός (ho astēr ho lampros ho prōinos), literally: the star, the shining one, the dawn. In the Vulgate Latin text of 2 Peter 1:19 the word "lucifer" is used of the morning star in the phrase "until the day dawns and the morning star rises in your hearts", the corresponding Greek word being φωσφόρος.
  • 3.2K
  • 31 Oct 2022
Topic Review
Nuclear Symmetry Energy
Nuclear symmetry energy is a measure of the energy cost to make nuclear systems more neutron rich. It depends on the density of the system. Information about the density dependence of nuclear symmetry energy has broad ramifications on the mechanisms of supernova explosions, properties of neutron stars and gravitational waves from their mergers. It is also important for understanding properties of nuclei as well as the dynamics and products of their collisions in laboratory experiments. 
  • 3.1K
  • 03 Aug 2021
Topic Review
Lagrangian Point
In celestial mechanics, the Lagrangian points (/ləˈɡrɑːndʒiən/ also Lagrange points, L-points, or libration points) are the points near two large bodies in orbit where a smaller object will maintain its position relative to the large orbiting bodies. At other locations, a small object would go into its own orbit around one of the large bodies, but at the Lagrangian points the gravitational forces of the two large bodies, the centripetal force of orbital motion, and (for certain points) the Coriolis acceleration all match up in a way that cause the small object to maintain a stable or nearly stable position relative to the large bodies. There are five such points, labeled L1 to L5, all in the orbital plane of the two large bodies, for each given combination of two orbital bodies. For instance, there are five Lagrangian points L1 to L5 for the Sun–Earth system, and in a similar way there are five different Lagrangian points for the Earth–Moon system. L1, L2, and L3 are on the line through the centers of the two large bodies, while L4 and L5 each act as the third vertex of an equilateral triangle formed with the centers of the two large bodies. L4 and L5 are stable, which implies that objects can orbit around them in a rotating coordinate system tied to the two large bodies. Several planets have trojan satellites near their L4 and L5 points with respect to the Sun. Jupiter has more than a million of these trojans. Artificial satellites have been placed at L1 and L2 with respect to the Sun and Earth, and with respect to the Earth and the Moon. The Lagrangian points have been proposed for uses in space exploration.
  • 3.0K
  • 17 Nov 2022
Topic Review
Supergiant Star
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spans from about 3,400 K to over 20,000 K.
  • 2.8K
  • 12 Oct 2022
Topic Review
KIC 8462852
KIC 8462852 (also Tabby's Star or Boyajian's Star) is an F-type main-sequence star located in the constellation Cygnus approximately 1,470 light-years (450 pc) from Earth. Unusual light fluctuations of the star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project. In September 2015, astronomers and citizen scientists associated with the project posted a preprint of an article describing the data and possible interpretations. The discovery was made from data collected by the Kepler space telescope, which observes changes in the brightness of distant stars to detect exoplanets. Several hypotheses have been proposed to explain the star's large irregular changes in brightness as measured by its light curve, but none to date fully explain all aspects of the curve. One explanation is that an "uneven ring of dust" orbits KIC 8462852. In another explanation, the star's luminosity is modulated by changes in the efficiency of heat transport to its photosphere, so no external obscuration is required. A third hypothesis, based on a lack of observed infrared light, posits a swarm of cold, dusty comet fragments in a highly eccentric orbit, however, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted. Another hypothesis is that a large number of small masses in "tight formation" are orbiting the star. Furthermore, spectroscopic study of the system has found no evidence for coalescing material or hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the mature central star. It has also been hypothesized that the changes in brightness could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm. The scientists involved are very skeptical, however, with others describing it as implausible. KIC 8462852 is not the only star that has large irregular dimmings, but all other such stars are young stellar objects called YSO dippers, which have different dimming patterns. An example of such an object is EPIC 204278916. New light fluctuation events of KIC 8462852 began in the middle of May 2017. Except for a period between late-December 2017 and mid-February 2018 when the star was obscured by the Sun, the fluctuations have continued (As of July 2018).
  • 2.7K
  • 15 Nov 2022
Topic Review
N1 (Rocket)
The N1/L3 (from Ракета-носитель Raketa-nositel', "Carrier Rocket"; Cyrillic: Н1) was a super heavy-lift launch vehicle intended to deliver payloads beyond low Earth orbit. The N1 was the Soviet counterpart to the US Saturn V and was intended to enable crewed travel to the Moon and beyond, with studies beginning as early as 1959. Its first stage, Block A, remains the most powerful rocket stage ever flown. However, all four first stages flown failed mid-flight because a lack of static test firings meant that plumbing issues and other adverse characteristics with the large cluster of thirty engines and its complex fuel and oxidizer feeder system were not revealed earlier in development. The N1-L3 version was designed to compete with the United States Apollo program to land a person on the Moon, using a similar lunar orbit rendezvous method. The basic N1 launch vehicle had three stages, which were to carry the L3 lunar payload into low Earth orbit with two cosmonauts. The L3 contained one stage for trans-lunar injection; another stage used for mid-course corrections, lunar orbit insertion, and the first part of the descent to the lunar surface; a single-pilot LK Lander spacecraft; and a two-pilot Soyuz 7K-LOK lunar orbital spacecraft for return to Earth. The N1-L3 was underfunded and rushed, starting development in October 1965, almost four years after the Saturn V. The project was badly derailed by the death of its chief designer Sergei Korolev in 1966. Each of the four attempts to launch an N1 failed, with the second attempt resulting in the vehicle crashing back onto its launch pad shortly after liftoff. The N1 program was suspended in 1974, and officially canceled in 1976. All details of the Soviet crewed lunar programs were kept secret until the USSR was nearing collapse in 1989.
  • 2.5K
  • 30 Nov 2022
Topic Review
Exoplanetology
Exoplanetology, or exoplanetary science, is an integrated field of astronomical science dedicated to the search for and study of exoplanets (extrasolar planets). It employs an interdisciplinary approach which includes astrobiology, astrophysics, astronomy, astrochemistry, astrogeology, geochemistry, and planetary science.
  • 2.4K
  • 09 Nov 2022
Topic Review
List of Meteor Air Bursts
Many explosions recorded in Earth's atmosphere are likely to be caused by the air bursts that result from meteors exploding as they hit the thicker part of the atmosphere. These types of meteors are also known as fireballs or bolides with the brightest known as superbolides. Before entering Earth's atmosphere, these larger meteors were originally asteroids and comets of a few to several tens of metres in diameter, contrasting with the much smaller and much more common "shooting stars". The most powerful recorded air burst is the 1908 Tunguska event. Extremely bright fireballs traveling across the sky are often witnessed from a distance, such as the 1947 Sikhote-Alin meteor and the 2013 Chelyabinsk meteor, both in Russia. If the bolide is large enough, fragments may survive such as the Chelyabinsk meteorite. Modern developments in infrasound detection by the Comprehensive Nuclear-Test-Ban Treaty Organization and infrared Defense Support Program satellite technology have increased the likelihood of detecting airbursts.
  • 2.2K
  • 11 Nov 2022
Topic Review
List of Largest Stars
Below is a list of the largest stars currently known, ordered by radius. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,300 mi). The angular diameters of stars can be measured directly using stellar interferometry. Other methods can use lunar occultations or from eclipsing binaries, which can be used to test indirect methods of finding stellar radii. Only a few useful supergiant stars can be occulted by the Moon, including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere (opacity) differs depending on the wavelength of light in which the star is observed. Uncertainties remain with the membership and order of the list, especially when deriving various parameters used in calculations, such as stellar luminosity and effective temperature. Often stellar radii can only be expressed as an average or be within a large range of values. Values for stellar radii vary significantly in different sources and for different observation methods. All the sizes stated in this list have various inaccuracies and may be disputed. This list is still a work in progress and various parameters are extremely disputed.
  • 2.1K
  • 21 Nov 2022
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