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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.
  • 2.9K
  • 11 Nov 2022
Topic Review
(225088) 2007 OR10
(225088) 2007 OR10, proposed to be named Gonggong, is a likely dwarf planet in the Solar System beyond Neptune, and is a member of the scattered disc. It has a highly eccentric and inclined orbit during which it ranges from 33–101 astronomical units (4.9–15.1 billion kilometers) from the Sun. (As of 2019), its distance from the Sun is 88 AU (1.32×1010 km; 8.2×109 mi), and it is the sixth-farthest known Solar System object. 2007 OR10 is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. 2007 OR10 was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory, and the discovery was announced in January 2009. At 1,230 km (760 mi) in diameter, 2007 OR10 is approximately the size of Pluto's moon Charon, and is the fifth-largest known trans-Neptunian object in the Solar System. It is sufficiently massive to be gravitationally rounded, thereby qualifying for dwarf planet status. Its large mass also makes retention of a tenuous atmosphere of methane just possible, though such an atmosphere would slowly escape into space. 2007 OR10 is currently the largest known body in the Solar System without an official name, but in 2019, the discoverers hosted an online poll for the general public to help choose a name for the object, and the name Gonggong won. The winning name is derived from Gonggong, a Chinese water god responsible for chaos, floods and the tilt of the Earth. 2007 OR10 is red in color, likely due to the presence of organic compounds called tholins on its surface. Water ice is also present on its surface, which hints at a brief period of cryovolcanic activity in the distant past. 2007 OR10 rotates slowly compared to other trans-Neptunian objects, which typically have rotation periods less than 12 hours, which may be due to its natural satellite, provisionally designated S/2010 (225088) 1.
  • 2.8K
  • 02 Dec 2022
Topic Review
White Hole
White holes are regions of space-time that although matter may come out, no matter is able to enter; or in other words, they have gravitational features opposite to those of black holes. White holes exist in the solutions to Einstein's general theory of relativity and the maximal extension of the Schwarzschild metric. The term "white hole" was coined by Soviet cosmologist Igor Novikov in 1965 after his theorization on the existence.
  • 2.5K
  • 15 Oct 2023
Topic Review
Orion
Orion, one of the most recognizable constellations in the night sky, is steeped in mythology and astronomical significance. Named after the legendary hunter from Greek mythology, Orion is adorned with bright stars, including the famous Orion's Belt, and hosts a plethora of celestial wonders, such as the Orion Nebula, making it a favorite among stargazers.
  • 2.4K
  • 15 Mar 2024
Topic Review
Yellow Supergiant Star
A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous. Yellow supergiants are smaller than red supergiants; naked eye examples include Polaris. Many of them are variable stars, mostly pulsating Cepheids such as δ Cephei itself.
  • 2.4K
  • 03 Nov 2022
Topic Review
88 Modern Constellations
In contemporary astronomy, the sky is divided into 88 regions called constellations, generally based on the asterisms (which are also called "constellations") of Greek and Roman mythology. The number of 88, along with the contemporary scientific notion of "constellation", was conventioned in 1922 by the International Astronomical Union in order to establish a universal pattern for professional astronomers, who defined constellations from then on as regions of the sky separated by arcs of right ascensions and declinations and grouped by asterisms of their historically most important stars, which cover the entire celestial sphere. The constellations along the ecliptic are called the zodiac. The ancient Sumerians, and later the Greeks (as recorded by Ptolemy), established most of the northern constellations in international use today. When explorers mapped the stars of the southern skies, European and American astronomers proposed new constellations for that region, as well as ones to fill gaps between the traditional constellations. Not all of these proposals caught on, but in 1922, the International Astronomical Union (IAU) adopted the modern list of 88 constellations. After this, Eugène Joseph Delporte drew up precise boundaries for each constellation, so that every point in the sky belonged to exactly one constellation.
  • 2.3K
  • 08 Oct 2022
Topic Review
Planet-Hosting Stars
Planet-hosting stars are stars which host planets, therefore forming planetary systems. This article describes the correlations between stars' characteristics and the characteristics of the planets that orbit them, and other connections between stars and their planets.
  • 2.2K
  • 23 Nov 2022
Topic Review
Draco
Draco, Latin for "the dragon," is a large and distinctive constellation in the northern celestial hemisphere. It is renowned for its winding shape, resembling a serpentine dragon winding around the celestial pole, and is home to several notable deep-sky objects, including the Cat's Eye Nebula and the Draco Dwarf Galaxy.
  • 2.2K
  • 08 Mar 2024
Topic Review
Ursa Major
Ursa Major, often referred to as the Great Bear, is one of the most recognizable and prominent constellations in the northern celestial hemisphere. Its distinctive shape, resembling a large bear with a long tail, has captivated human imagination for millennia. At the heart of Ursa Major lies the Big Dipper, a prominent asterism formed by seven bright stars that serve as a navigational guide and cultural icon across cultures and civilizations.
  • 2.1K
  • 15 Mar 2024
Biography
Albert Einstein
Albert Einstein, born on March 14, 1879, in Ulm, Germany, is widely regarded as one of the most brilliant scientists in human history. His groundbreaking contributions to physics revolutionized our understanding of the universe and earned him worldwide acclaim. Einstein's life and work remain a source of inspiration and fascination, making him an iconic figure in the realm of science and beyond
  • 2.0K
  • 21 Feb 2024
Topic Review
1769 Transit of Venus Observed from Tahiti
On June 3, 1769, British navigator Captain James Cook, British naturalist Joseph Banks, British astronomer Charles Green and Swedish naturalist Daniel Solander recorded the transit of Venus on the island of Tahiti during Cook's first voyage around the world. During a transit, Venus appears as a small black disc travelling across the Sun. This unusual astronomical phenomenon takes place in a pattern that repeats itself every 243 years. It includes two transits that are eight years apart, separated by breaks of 121.5 and 105.5 years. These men, along with a crew of scientists, were commissioned by the Royal Society of London for the primary purpose of viewing the transit of Venus. Not only would their findings help expand scientific knowledge, it would help with navigation by accurately calculating the observer's longitude. At this time, longitude was difficult to determine and not always precise. A "secret" mission that followed the transit included the exploration of the South Pacific to find the legendary Terra Australis Incognita or "unknown land of the South."
  • 2.0K
  • 30 Sep 2022
Topic Review
COROT-7b
COROT-7b (previously named COROT-Exo-7b) is an exoplanet orbiting around the star COROT-7, in the constellation Monoceros, at 489 light years from Earth. It was first detected photometrically by the French-led COROT mission and reported in February 2009. Until the announcement of Kepler-10b in January 2011, it was the smallest exoplanet to have its diameter measured, at 1.58 times that of the Earth (which would give it a volume 3.95 times Earth's), and the first potential extrasolar terrestrial planet to be found. The planet has a very short orbital period, revolving around its host star in about 20 hours. Combination of the planet's diameter derived from transit data with the planet's mass derived from radial velocity measurements, meant that the density of CoRoT-7b was about the same as that of Earth and, therefore, that CoRoT-7b was made of rock like Earth and was not a gas giant like Jupiter. The radial velocity observations of CoRoT-7 also detected a second super-Earth, CoRoT-7c, which has a mass 8.4 times that of Earth and orbits every 3.7 days at a distance of 6.9 million km (4.3 million miles).
  • 2.0K
  • 19 Oct 2022
Topic Review
Lunar Outpost (NASA)
A lunar outpost is a concept of a permanent or semi-permanent presence of humans on the Moon, a moonbase, by the United States space administration NASA. NASA requested an increase in the 2020 budget of $1.6 billion, in order to make another crewed mission to the Moon by 2025 (originally 2024), followed by a sustained presence on the Moon by 2028.
  • 2.0K
  • 23 Nov 2022
Topic Review
Lyra
Lyra is a constellation in the northern celestial hemisphere known for its prominent star Vega, one of the brightest stars in the sky. Represented as a lyre, a musical instrument from Greek mythology, Lyra is rich in celestial objects. Lyra is bordered by Vulpecula to the south, Hercules to the west, Draco to the north, and Cygnus to the east.
  • 2.0K
  • 15 Mar 2024
Topic Review
Cosmogenic Activation
       The cosmogenic activation of materials is the production of radioactive isotopes due to the exposure to cosmic rays. On the Earth's surface, spallation induced by cosmic neutrons is responsible of most of the activation, but other reactions and cosmic ray components must be considered too in other conditions, like if materials are flown at high altitudes or stored deep underground.        Cosmogenic activation is relevant in different contexts; for example, together with primordial or anthropogenic radioactivity, it s a background source in experiments devoted to the investigation of rare event phenomena, like the direct detection of dark matter particles or the nuclear double beta decay. 
  • 1.9K
  • 26 Oct 2020
Topic Review
Standard and Alternative Cosmology
The Standard and The Alternative Cosmological Models, Distances Calculation to Galaxies without Hubble Constant For the alternative cosmological models considered in the extended version of this entry, the distances  are calculated for galaxies without using the Hubble constant. This process is mentioned in the second narrative, and described in detail in the third narration. According to the third narrative, as the density of the relativistic mass of the universe decreases while the universe expands, new matter is created by a phase transition process which results in a continuously constant ordinary density of matter. While the universe develops on the basis of this postulate of the emergence of new matter, it is "assumed that matter arises as a result of such a phase transition of dark energy into both new dark and visible matter. It is somewhat irrelevant how we describe dark energy, calling it aether, or vice versa, the changing of aether into dark energy. It should be clear to everyone that this renaming does not change the essence of this phase transition phenomena. It should be noted that, unlike all well‐known geometric models of the Euclidean space of our existence, this phase transition of dark energy into matter would accordingly be a stereographic projection of a three‐dimensional surface on to a four‐dimensional globe.
  • 1.9K
  • 29 Oct 2020
Topic Review
Mars (Planet)
Mars is the fourth planet from the Sun in our solar system and is named after Mars, the Roman god of war. Mars is also known as the "Red Planet" due to its reddish appearance when seen from Earth. The prefix areo-, from the Greek god of war, Ares, refers to Mars in the same way geo- refers to Earth. Until the first flyby of Mars by Mariner 4 in 1965, it was thought that Mars had channels of liquid water. Observations later showed that these channels do not exist. Still, of all the planets in our solar system other than Earth, Mars is the most likely to harbor liquid water, and perhaps life. Its rotational period and seasonal cycles are also similar to those of the Earth. It has the highest mountain in the solar system, Olympus Mons, the largest canyon in the solar system, Valles Marineris, and polar ice caps. Mars has two moons, Phobos and Deimos, which are small and oddly-shaped. These may be captured asteroids similar to 5261 Eureka, a Mars trojan asteroid. Mars can be seen from Earth by the naked eye. Its apparent magnitude reaches -2.9, a brightness surpassed only by Venus, the Moon, and the Sun. For much of the year, Jupiter may appear brighter to the naked eye than Mars. Mars is currently host to four orbiting spacecraft, more than any planet other than Earth. It is also home to the two Mars Exploration Rovers, Spirit and Opportunity.
  • 1.9K
  • 21 Nov 2022
Topic Review
Asterism
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observations. For example the Summer Triangle is a purely observational physically unrelated group of stars, but the stars of Orion's Belt are all members of the Orion OB1 association and five of the seven stars of the Big Dipper are members of the Ursa Major Moving Group. Physical associations, such as the Hyades or Pleiades, can be asterisms in their own right and part of other asterism at the same time.
  • 1.9K
  • 29 Nov 2022
Biography
Mazlan Othman
Professor Emerita Dato' Seri Dr Mazlan binti Othman (born 11 December 1951) is a Malaysian astrophysicist whose work has pioneered Malaysia's participation in space exploration. She was her country's first astrophysicist, and helped to create a curriculum in astrophysics at the national university, as well as to build public awareness and understanding of astronomy and space issues. She was appo
  • 1.8K
  • 18 Nov 2022
Topic Review
List of Objects at Lagrangian Points
This is a list of known objects which occupy, have occupied, or are planned to occupy any of the five Lagrangian points of two-body systems in space.
  • 1.8K
  • 08 Nov 2022
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