Search | Encyclopedia MDPI

You're using an outdated browser. Please upgrade to a modern browser for the best experience.

Subject:

Sort by:

Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)

Filter:

All Topic Review Biography Peer Reviewed Entry Video Entry

Topic Review

Monoceros, Latin for "unicorn," is a constellation located in the celestial equator. Despite lacking ancient mythological roots, it was introduced in the 17th century by the astronomer Jakob Bartsch and later included in Johann Bayer's Uranometria, symbolizing the unicorn, a creature of myth and fantasy.

2.1K
15 Mar 2024

Topic Review

Zeta Ursae Majoris

Mizar is a 2nd magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris (Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.

2.0K
29 Sep 2022

Topic Review

Large Synoptic Survey Telescope

The Large Synoptic Survey Telescope (LSST) is a wide-field survey reflecting telescope with an 8.4-meter primary mirror, currently under construction, that will photograph the entire available sky every few nights. The word synoptic is derived from the Greek words σύν (syn "together") and ὄψις (opsis "view"), and describes observations that give a broad view of a subject at a particular time. The telescope uses a novel 3-mirror design, a variant of three-mirror anastigmat, which allows a compact telescope to deliver sharp images over a very wide 3.5-degree diameter field of view. Images will be recorded by a 3.2-gigapixel CCD imaging camera, the largest digital camera ever constructed. The telescope is located on the El Peñón peak of Cerro Pachón, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile , alongside the existing Gemini South and Southern Astrophysical Research Telescopes. The LSST Base Facility is located about 100 kilometres (62 mi) away by road, in the town of La Serena. The LSST was proposed in 2001, and construction of the mirror began (with private funds) in 2007. LSST then became the top-ranked large ground-based project in the 2010 Astrophysics Decadal Survey, and the project officially began construction 1 August 2014 when the National Science Foundation (NSF) authorized the FY2014 portion ($27.5 million) of its construction budget. The ceremonial laying of the first stone was performed on 14 April 2015. Site construction began on April 14, 2015, with engineering first light anticipated in 2019, science first light in 2021, and full operations for a ten-year survey commencing in January 2022. LSST, unlike almost all previous large astronomical observatories, has committed to making all data public as soon as it is taken. In their words "By providing immediate public access to all the data it obtains, it will provide everyone, the professional and the “just curious” alike, a deep and frequent window on the entire sky."

2.0K
10 Nov 2022

Topic Review

Aquila, a constellation in the northern celestial hemisphere, is renowned for its striking resemblance to an eagle soaring through the heavens. Designated by the International Astronomical Union (IAU), Aquila captivates observers with its prominent stars and rich astronomical history, making it a prominent feature in both ancient mythology and modern astronomy.

2.0K
29 Feb 2024

Topic Review

Solar System Model

Solar System models, especially mechanical models, called orreries, that illustrate the relative positions and motions of the planets and moons in the Solar System have been built for centuries. While they often showed relative sizes, these models were usually not built to scale. The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the Solar System a challenging task. As one example of the difficulty, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth. If the smaller planets are to be easily visible to the naked eye, large outdoor spaces are generally necessary, as is some means for highlighting objects that might otherwise not be noticed from a distance. The Boston Museum of Science has placed bronze models of the planets in major public buildings, all on similar stands with interpretive labels. For example, the model of Jupiter is located in the cavernous South Station waiting area. The properly-scaled, basket-ball-sized model is 1.3 miles (2.14 km) from the model Sun which is located at the museum, graphically illustrating the immense empty space in the Solar System. The objects in such large models do not move. Traditional orreries often did move, and some used clockworks to display the relative speeds of objects accurately. These can be thought of as being correctly scaled in time, instead of distance. Modern digital simulations now complement these mechanical representations, enabling interactive exploration of planetary orbits, relative velocities, and dynamic trajectories, thereby enhancing education and public engagement with astronomy.

2.0K
19 Sep 2025

Topic Review

Eridanus, the constellation named after the ancient Greek river god, is a sprawling celestial feature stretching across the southern sky. It is the sixth largest of the 88 modern constellations, rich in diverse astronomical treasures.

2.0K
15 Mar 2024

Topic Review

Aries, recognized by the International Astronomical Union (IAU), is a constellation in the northern celestial hemisphere. Representing the ram from ancient Greek mythology, Aries is one of the twelve zodiac constellations and holds significance in astrology and astronomy alike. Its celestial prominence and position along the ecliptic make it a notable feature in the night sky, marking the vernal equinox and heralding the beginning of spring in the northern hemisphere.

1.9K
29 Feb 2024

Topic Review

Alpha Crucis (α Crucis, abbreviated Alpha Cru, α Cru) is a multiple star system 321 light-years from the Sun in the constellation of Crux and part of the asterism known as the Southern Cross. With a combined visual magnitude of 0.76, it is the brightest star in Crux and the 13th brightest star in the night sky. It is the southernmost first-magnitude star, 2.3 degrees more southerly than Alpha Centauri. To the naked eye Alpha Crucis appears as a single star, but it is actually a multiple star system. Two components are visually distinguishable: α1 Crucis and α2 Crucis; alternatively designated α Crucis A and α Crucis B. Both are B-type stars, and are many times more massive and luminous than the Sun. α1 Crucis is itself a spectroscopic binary with components designated α Crucis Aa (also named Acrux) and α Crucis Ab. Its two component stars orbit every 76 days at a separation of about 1 astronomical unit (au).

1.9K
08 Oct 2022

Topic Review

International Space Station Maintenance

Since construction started, the International Space Station (ISS) programme has had to deal with several maintenance issues, unexpected problems and failures. These incidents have affected the assembly timeline, led to periods of reduced capabilities of the station and in some cases could have forced the crew to abandon the space station for safety reasons, had these problems not been resolved.

1.9K
02 Nov 2022

Topic Review

Luch (Satellite)

The Luch (Russian: Луч; lit. Ray) Satellite Data Relay Network (SDRN), also referred to as Altair and Gelios, is a series of geosynchronous Russian relay satellites, used to transmit live TV images, communications and other telemetry from the Soviet/Russian space station Mir, the Russian Orbital Segment (ROS) of the International Space Station and other orbital spacecraft to the Earth, in a manner similar to that of the US Tracking and Data Relay Satellite System.

1.9K
21 Nov 2022

Topic Review

Asteroids, Meteoroids, Meteors, Meteorites, Comets

A celestial body bigger than 10 m orbiting the Sun, mainly between Mars and Jupiter. Meteoroid is similar to an asteroid, but significantly smaller. Mostly debris of comets, sometimes debris of asteroids. Meteor is a bright tail of light caused by a meteoroid during its atmospheric flight, also called a shooting star or falling star. Fireball is a very bright meteor (brighter than the planet Venus). Bolide is a fireball that explodes during its atmospheric flight, often with visible fragmentation. The part of a meteoroid or asteroid that survives the passage through our atmosphere and reaches the Earth's surface. A smaller celestial body mainly composed of ice and dust. If a comet approaches the Sun it can generate a tail of gas and/or dust.

1.9K
25 Mar 2025

Topic Review

PSR B1620-26 b is an extrasolar planet located approximately 12,400 light-years away from Earth in the constellation of Scorpius. It bears the unofficial nicknames "Methuselah" and "the Genesis planet" due to its extreme age and a few popular sources refer to this object as "PSR B1620-26 c" (see below for discussion). The planet is in a circumbinary orbit around the two stars of PSR B1620-26 (which are a pulsar (PSR B1620-26 A) and a white dwarf (WD B1620-26)) and is the first circumbinary planet ever confirmed. It is also the first planet found in a globular cluster. The planet is one of the oldest known extrasolar planets, believed to be about 12.7 billion years old.

1.9K
28 Nov 2022

Topic Review

Soyuz 1 (Russian: Союз 1, Union 1) was a crewed spaceflight of the Soviet space program. Launched into orbit on 23 April 1967 carrying cosmonaut colonel Vladimir Komarov, Soyuz 1 was the first crewed flight of the Soyuz spacecraft. The flight was plagued with technical issues, and Komarov was killed when the descent module crashed into the ground due to a parachute failure. This was the first in-flight fatality in the history of spaceflight. The original mission plan was complex, involving a rendezvous with Soyuz 2 and an exchange of crew members before returning to Earth. However, the launch of Soyuz 2 was called off due to thunderstorms.

1.9K
22 Nov 2022

Topic Review

Corona Borealis

Corona Borealis, Latin for "Northern Crown," is a constellation in the northern celestial hemisphere, known for its distinctive semicircular shape resembling a crown. Its counterpart in the southern hemisphere, Corona Australis, shares a similar name and mythological association with crowns but lies on the opposite side of the celestial sphere.

1.8K
08 Mar 2024

Topic Review

Wide Field Infrared Survey Telescope

The Wide Field Infrared Survey Telescope (WFIRST) is a NASA infrared space observatory currently under development. WFIRST was recommended in 2010 by United States National Research Council Decadal Survey committee as the top priority for the next decade of astronomy. On February 17, 2016, WFIRST was approved for development and launch. WFIRST is based on an existing 2.4 m wide field-of-view telescope and will carry two scientific instruments. The Wide-Field Instrument is a 288-megapixel multi-band near-infrared camera, providing a sharpness of images comparable to that achieved by the Hubble Space Telescope (HST) over a 0.28 square degree field of view, 100 times larger than that of the HST. The Coronagraphic Instrument is a high-contrast, small field-of-view camera and spectrometer covering visible and near-infrared wavelengths using novel starlight-suppression technology. The design of WFIRST is based on one of the proposed designs for the Joint Dark Energy Mission between NASA and DOE. WFIRST adds some extra capabilities to the original JDEM proposal, including a search for extra-solar planets using gravitational microlensing. In its present incarnation (2015), a large fraction of its primary mission will be focused on probing the expansion history of the Universe and the growth of cosmic structure with multiple methods in overlapping redshift ranges, with the goal of precisely measuring the effects of dark energy, the consistency of general relativity, and the curvature of spacetime. On February 12, 2018, development on the WFIRST mission was proposed to be terminated in the President's FY19 budget request, due to a reduction in the overall NASA astrophysics budget and higher priorities elsewhere in the agency. However, in March 2018 Congress approved funding to continue making progress on WFIRST until at least September 30, 2018, in a bill stating that Congress "rejects the cancellation of scientific priorities recommended by the National Academy of Sciences decadal survey process".[needs update] In testimony before Congress in July 2018, NASA administrator Jim Bridenstine proposed slowing down the development of WFIRST in order to accommodate a cost increase in the James Webb Space Telescope (JWST), which would result in decreased[clarification needed] funding for WFIRST in 2020/2021. In the President's FY2020 budget request, termination of WFIRST was proposed again, due to cost overruns and higher priority for JWST.. The telescope received $511 million for FY2020.

1.8K
29 Nov 2022

Topic Review

List of Messier Objects

The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his "Catalogue des Nébuleuses et des Amas d'Étoiles" ("Catalogue of Nebulae and Star Clusters"). A preliminary version first appeared in Memoirs of the French Academy of Sciences in 1771, and the last item was added in 1966 by Kenneth Glyn Jones, based on Messier's observations. The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier’s. By 1780 the catalog had increased to 80 objects. The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784. However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects. The catalogue consists of a diverse range of astronomical objects, ranging from star clusters, nebula and galaxies. Messier 1 is the supernova remnant of Crab Nebula and the great spiral Andromeda Galaxy is M 31. Many further inclusions followed in the next century when the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier’s side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967. Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

1.8K
06 Dec 2022

Topic Review

Grahan Mala is an astronomical treatise on the calculation of the dates and timings for the lunar and solar eclipses written by the Indian Astronomer Hemangad Thakur in the 16th century AD.

1.8K
15 Dec 2023

Topic Review

Crux, commonly known as the Southern Cross, is a small but distinctive constellation located in the southern celestial hemisphere. Recognized for its iconic shape resembling a cross, Crux holds cultural significance across various civilizations and is one of the most recognizable asterisms in the night sky. Positioned close to the South Celestial Pole, Crux serves as a navigational aid for travelers in the southern hemisphere and has been used for centuries by sailors and explorers to determine directions.

1.8K
08 Mar 2024

Topic Review

Former Constellation

Former constellations are old historical Western constellations that for various reasons are no longer widely recognised or are not officially recognised by the International Astronomical Union (IAU). Prior to 1930, many of these defunct constellations were traditional in one or more countries or cultures. Some only lasted decades but others were referred to over many centuries. All are now recognised only for having classical or historical value. Many former constellations had complex Latinised names after objects, people, or mythological or zoological creatures. Others with unwieldy names were shortened for convenience. For example, Scutum Sobiescianum was reduced to Scutum, Mons Mensae to Mensa, and Apparatus Sculptoris to Sculptor. Some of the Northern Sky's former constellations were placed in the less populated regions between the traditional brighter constellations just to fill gaps. In the Southern Sky, new constellations were often created from about the 15th century by voyagers who began journeying south of the Equator. European countries like England, France, the Netherlands, German or Italian states, etc., often supported and popularised their own constellation outlines. In some cases, different constellations occupied overlapping areas and included the same stars. These former constellations are often found in older books, star charts, or star catalogues. The 88 modern constellation names and boundaries were standardised by Eugene Delporte for the IAU in 1930, under an international agreement, removing any possible astronomical ambiguities between astronomers from different countries. Nearly all former or defunct constellations differ in their designated boundaries in as much as they have outlines that do not follow the exact lines of right ascension and declination.

1.8K
05 Nov 2022

Topic Review

Boötes, recognized by the International Astronomical Union (IAU), is a constellation in the northern celestial hemisphere. It is known for its prominent shape resembling a kite or an ice cream cone, with its brightest star, Arcturus, marking one corner.

1.8K
29 Feb 2024

Page
of
13

Featured Entry Collections

>>

Featured Books

>>

Encyclopedia of COVID-19

Encyclopedia of Engineering

Encyclopedia of Social Sciences

Encyclopedia of Social Sciences
Chief Editor: Kum Fai Yuen

Encyclopedia of Digital Society, Industry 5.0 and Smart City

Encyclopedia of Digital Society, Industry 5.0 and Smart City
Chief Editor: Sandro Serpa

Academic Video Service

Feedback

Top