comets

Cosmic dust - Introductory Material. Cosmic Dust refers to particles in space which are assemblages of a few molecules to tenth-millimeter-sized grains. Cosmic dust can be further distinguished by its astronomical location; for example: interplanetary dust, interstellar dust, comet dust, circumplanetary dust. This article covers bulk and radiative properties of cosmic dust, the dust particles' origins, end-fates, and specific locations in space. Historically, cosmic dust used to be an annoyanc ...

Including:

• Cosmic dust - Introductory Material
• Cosmic dust - Some bulk properties of cosmic dust
• Cosmic dust - Radiative properties of cosmic dust
• Cosmic dust - Dust grain formation
• Cosmic dust - Dust grain destruction
• Cosmic dust - Some dusty clouds in the universe

Read more here: » Cosmic dust: Encyclopedia - Cosmic dust

Damocloids are asteroids such as 5335 Damocles and 1996 PW that have Halley family or long-period highly eccentric orbits typical of periodic comets such as Comet Halley, but without showing a cometary coma or tail. Damocloids are believed to be nuclei of Halley-type comets that have lost all their volatile materials due to outgassing. Such comets are believed to originate from the Oort cloud. This hypothesis is strengthened by the fact that a number of objects thought to be Damocloids (and assigned minor planet provisional des ...

Including:

• Damocloid asteroid - External link

Read more here: » Damocloid asteroid: Encyclopedia - Damocloid asteroid

The Cretaceous-Tertiary (K-T or KT) extinction event, also known as the KT boundary, was a period of massive extinction of species, about 65.5 million years ago. It corresponds to the end of the Cretaceous Period and the beginning of the Tertiary Period. (K is the traditional abbreviation for the Cretaceous period. Cretaceous comes from the Latin for chalk, creta. The K comes from the German word for chalk kreide, or possibly Greek kreta. The K is used so as ...

Including:

• Cretaceous-Tertiary extinction event - Casualties of the extinction
• Cretaceous-Tertiary extinction event - Theories
• Cretaceous-Tertiary extinction event - Alvarez hypothesis
• Cretaceous-Tertiary extinction event - Chicxulub crater
• Cretaceous-Tertiary extinction event - Deccan traps
• Cretaceous-Tertiary extinction event - Multiple impact event
• Cretaceous-Tertiary extinction event - Supernova hypothesis
• Cretaceous-Tertiary extinction event - Further skepticism
• Cretaceous-Tertiary extinction event - Other mass extinctions

Read more here: » Cretaceous-Tertiary extinction event: Encyclopedia - Cretaceous-Tertiary extinction event

In astronomy, a compact star (sometimes called a compact object) is a star that is a white dwarf, a neutron star, an exotic star, or a black hole. "Compact star" is often used when the exact nature of the star is not known, but evidence suggests it is very massive and has small radius, thus leaving the above-mentioned possibilities. Compact star - Compact stars as the endpoint of stellar evolution. Compact stars form the endpoint of stellar evolution. A star shines and thus loses energy. The loss from the r ...

Including:

• Compact star - Compact stars as the endpoint of stellar evolution
• Compact star - Compact stars last forever
• Compact star - Thought experiment in building compact objects
• Compact star - Planets
• Compact star - The largest cold mass in the universe
• Compact star - White dwarfs
• Compact star - Neutron stars
• Compact star - Exotic stars
• Compact star - Strange stars
• Compact star - Preon stars
• Compact star - Black holes

Read more here: » Compact star: Encyclopedia - Compact star

Some of the moons of the outer planets of the solar system are large enough to be suitable places for colonization. Many of the larger moons contain water ice, liquid water, and organic compounds that might be useful for rocket fuel production among other things. Colonies in the outer solar system could also serve as centres for long term investigation of the planet and the other moons. In particular, robotic devices could be controlled by humans without the very long time delays needed to communicate with Earth. There have also been proposa ...

Including:

• Colonization of the outer solar system - Asteroids
• Colonization of the outer solar system - Ceres
• Colonization of the outer solar system - Jupiter
• Colonization of the outer solar system - Europa
• Colonization of the outer solar system - Ganymede
• Colonization of the outer solar system - Callisto
• Colonization of the outer solar system - Saturn
• Colonization of the outer solar system - Titan
• Colonization of the outer solar system - Uranus
• Colonization of the outer solar system - Neptune
• Colonization of the outer solar system - Kuiper Belt and Oort Cloud

Read more here: » Colonization of the outer solar system: Encyclopedia - Colonization of the outer solar system

The centaurs are a class of icy planetoids that orbit the Sun between Jupiter and Neptune, named after the mythical race of centaurs. The first centaur to be discovered, 2060 Chiron was found to display a coma upon its approach to perihelion, and is now officially classified as both a comet (95/P Chiron) and an asteroid, although it is far larger than a typical comet and there is some lingering controversy. Other centaurs are being monitored for comet-like activity. Centaurs are not in stable orbits and will eventually b ...

Read more here: » Centaur planetoid: Encyclopedia - Centaur planetoid

In heraldry, a charge is the image that occupies the field on an escutcheon (or shield). The most common charges, or "ordinaries", are geometric constructs such as crosses and saltires. Other charges include animals, plants, astronomical objects and tools ranging from those of ancient vintage to locomotives (railroads also occur in the arms of a handful of units of the United States Army), airplanes (the arms of Beddington and Wallington specify a "Hannibal Aircraft"), a satellite (in the arms of Arthur Maxwell House). "Atomic" charge ...

Including:

• Charge heraldry - Tinctures
• Charge heraldry - Proper charges
• Charge heraldry - Honourable Ordinaries
• Charge heraldry - Sub-Ordinaries
• Charge heraldry - Diminutives
• Charge heraldry - Common charges
• Charge heraldry - Supernatural or Divine beings
• Charge heraldry - Humans
• Charge heraldry - Animals
• Charge heraldry - Plants
• Charge heraldry - Inanimate charges

Read more here: » Charge heraldry: Encyclopedia - Charge heraldry

Adrien Auzout (January 28th, 1622–May 23rd, 1691) was a French astronomer. He was born in Rouen, France, the son of a clerk in the court of Rouen. His educational background is unknown. In 1664–1665 made observations of comets, and argued in favor of their following elliptical or parabolic orbits. (In this he was opposed by his rival Johannes Hevelius.) Adrien was briefly a member of the Académie Royale des Sciences from 1666 to 1668, and a founding member of the french Royal Obseratory. (He may have left the academy due t ...

Read more here: » Adrien Auzout: Encyclopedia - Adrien Auzout

Vulcanoids are hypothetical asteroids that may orbit in a dynamically stable zone between 0.08 and 0.21 astronomical units from the Sun, well within the orbit of Mercury. They take their name from the hypothetical planet Vulcan, which eighteenth-century astronomers fruitlessly searched for to explain the excess precession of Mercury's perihelion. The anomaly in Mercury's orbit later turned out to be an effect explained by general relativity ...

Read more here: » Vulcanoid asteroid: Encyclopedia - Vulcanoid asteroid

Carbon is a chemical element in the periodic table that has the symbol C and atomic number 6. An abundant nonmetallic, tetravalent element, carbon has several allotropic forms: Diamond (hardest known natural mineral). Structure: each atom is bonded tetrahedrally to four others, making a 3-dimensional network of puckered six-membered rings of atoms. Graphite (one of the softest substances). Structure: each atom is bonded trigonally to three other atoms, making a 2-dimensional network of flat s ...

Including:

• Carbon - Notable characteristics
• Carbon - Applications
• Carbon - Other uses
• Carbon - History and Etymology
• Carbon - Allotropes
• Carbon - Occurrence
• Carbon - Organic compounds
• Carbon - Carbon chains
• Carbon - Carbon cycle
• Carbon - Isotopes
• Carbon - Precautions

Read more here: » Carbon: Encyclopedia - Carbon

Archaeoastronomy (also spelled Archeoastronomy) is the study of astronomy in its cultural context, drawing on archaeological and anthropological evidence. One aspect of it employs astronomical examination of archaeological sites to gain insights into the roles of astronomy in past cultures. A second aspect (sometimes known by the term ethnoastronomy) examines anthropological and ethnohistorical evidence for the astronomical practices of more modern, historical cultures. A third aspect of archaeoastronomy focuses on the c ...

Including:

• Archaeoastronomy - Some Old World sites where archaeoastronomy is being explored
• Archaeoastronomy - Some New World sites where archaeoastronomy is being explored
• Archaeoastronomy - Some artifacts that throw light on archaeoastronomy

Read more here: » Archaeoastronomy: Encyclopedia - Archaeoastronomy

Georges-Louis Leclerc, Comte de Buffon (September 7, 1707 – April 16, 1788) was a French naturalist, mathematician, biologist, cosmologist and author. Buffon's views influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Charles Darwin. Buffon's legacy is as direct and powerful as that of his monarch, Louis XVI. Buffon is best remembered for his great work Histoire naturelle, générale et particulière (1749-1788: in 36 volumes, 8 additional volumes published after his death by Lacép� ...

Including:

• Georges-Louis Leclerc Comte de Buffon - Wood tests
• Georges-Louis Leclerc Comte de Buffon - Endnotes

Read more here: » Georges-Louis Leclerc Comte de Buffon: Encyclopedia - Georges-Louis Leclerc Comte de Buffon

A disaster (from Latin meaning, "bad star") is the impact of a natural or man-made event that negatively affects life, property, livelihood or industry often resulting in permanent changes to human societies, ecosystems and environment. (It may be noted that event itself is not a disaster, it is the impact which is called disaster.) Disasters manifest as hazards exacerbating vulnerable conditions and exceeding individuals' and communities' means to survive and thrive. Most events included herein are compiled from United States Federal Emergency Management Age ...

Including:

• Disaster - Natural disasters
• Disaster - Avalanche
• Disaster - Cold
• Disaster - Disease
• Disaster - Drought
• Disaster - Earthquake
• Disaster - Famine
• Disaster - Fire
• Disaster - Flood
• Disaster - Hail
• Disaster - Heat
• Disaster - Hurricane
• Disaster - Impact event
• Disaster - Limnic eruption
• Disaster - Landslide
• Disaster - Mudslide
• Disaster - Sink hole
• Disaster - Solar flare
• Disaster - Storm surge
• Disaster - Thunderstorm
• Disaster - Tornado
• Disaster - Tsunami
• Disaster - Volcanic eruption
• Disaster - Waterspout
• Disaster - Winter storm
• Disaster - Man-made disasters
• Disaster - Aviation
• Disaster - Arson
• Disaster - CBRNs
• Disaster - Civil disorder
• Disaster - Crime
• Disaster - Data loss
• Disaster - Dam failure
• Disaster - Hazardous materials
• Disaster - Processing interruption
• Disaster - Liquidity shortage
• Disaster - Power outage
• Disaster - Public relations crisis
• Disaster - Radiation Contamination
• Disaster - Space Disasters
• Disaster - Telecommunication outage
• Disaster - Terrorism
• Disaster - War
• Disaster - Surviving a disaster
• Disaster - Personal and family disaster preparation
• Disaster - Local government and emergency services disaster preparation and management
• Disaster - Business disaster preparation and management
• Disaster - National disaster preparation
• Disaster - Humanitarian disaster preparation
• Disaster - Information security disaster preparation

Read more here: » Disaster: Encyclopedia - Disaster

A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star that is not a star itself. The name comes from the Greek term πλανήτης, planētēs, meaning "wanderer", as ancient astronomers noted how certain lights moved across the sky in relation to the other stars. Based on historical consensus, the International Astronomical Union (IAU) lists nine planets in our solar system. Since the term "planet" has no precise scientific definition, however, many astronomers contest that ...

Including:

• Planet - Planetary formation
• Planet - Within our solar system
• Planet - Accepted planets
• Planet - Other candidates
• Planet - Extrasolar planets
• Planet - Brown dwarf planets
• Planet - Interstellar planets
• Planet - Definition and classification of planets
• Planet - Suggested wide definitions
• Planet - Suggested narrow definitions
• Planet - Further classification

Read more here: » Planet: Encyclopedia - Planet

Panspermia is the hypothesis that the seeds of life are ubiquitous in the universe, that they may have delivered life to Earth, and that they may deliver or have delivered life to other habitable bodies; also the process of such delivery. Exogenesis is a related, but less radical, hypothesis that simply proposes life originated elsewhere in the universe and was transferred to Earth, with no prediction about how widespread life is. The term "panspermia" is more well-known, however, and tends to be used in reference to wha ...

Including:

• Panspermia - The panspermia theory
• Panspermia - Evidence
• Panspermia - Narrow time window for geogenesis
• Panspermia - Extremophiles
• Panspermia - Wider range of potential habitats for life
• Panspermia - Evidence of extraterrestrial life
• Panspermia - Objections to panspermia and exogenesis
• Panspermia - Directed panspermia
• Panspermia - Science fiction

Read more here: » Panspermia: Encyclopedia - Panspermia

Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally, "law of the stars") is the science of celestial objects and phenomena that originate outside the Earth's atmosphere, such as stars, planets, comets, galaxies, and the cosmic background radiation. It is concerned with the formation and development of the universe, the evolution and physical and chemical properties of celestial objects and the calculation of their motions. Astronomical observations are ...

Including:

• Astronomy - Divisions
• Astronomy - By subject or problem addressed
• Astronomy - Ways of obtaining information
• Astronomy - History of astronomy
• Astronomy - Timelines in astronomy
• Astronomy - Astronomy tools

Read more here: » Astronomy: Encyclopedia - Astronomy

Dust is a general name for minute solid particles of diameters less than 500 micrometers (otherwise see sand or granulates) and, more generally, for finely divided matter. On Earth, dust occurs in the atmosphere from various sources: soil dust lifted up by wind, volcanic eruptions, and pollution are some examples; airborne dust is considered an aerosol and can have a strong, local radiative forcing on the atmosphere and significant effects on climate. In addition, if composed of a flammable substance (suc ...

Including:

• Dust - House dust
• Dust - Dust in outer space
• Dust - Reference

Read more here: » Dust: Encyclopedia - Dust

In physics, an orbit is the path that an object makes around another object while under the influence of a source of centripetal force, such as gravity. Planetary orbit - History. Orbits were first analysed mathematically by Johannes Kepler who formulated his results in his three laws of planetary motion. First, he found that the orbits of the planets in our solar system are elliptical, not circular (or epicyclic), as had previously been believed, and that the sun is not located at the center of the orbits, ...

Including:

• Planetary orbit - History
• Planetary orbit - Planetary orbits
• Planetary orbit - Understanding orbits
• Planetary orbit - Newton's laws of motion
• Planetary orbit - Analysis of orbital motion
• Planetary orbit - Orbital parameters
• Planetary orbit - Orbital period
• Planetary orbit - Orbital decay
• Planetary orbit - Earth orbits
• Planetary orbit - Scaling in gravity
• Planetary orbit - Role in the evolution of atomic theory

Read more here: » Planetary orbit: Encyclopedia - Planetary orbit

Ocean (from Okeanos, Greek for river, the ancient Greeks noticed that a strong current flowed off Gibraltar, and assumed it was a great river); covers almost three quarters (71%) of the surface of the Earth, and nearly half of the world's marine waters are over 3000 m deep. This global, interconnected body of salt water, called the World Ocean, is divided by the continents and archipelagos into the following four bodies, from the largest to the smallest: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean, and, according to some authorities such as International Hydrographic Organizati ...

Including:

• Ocean - Origins
• Ocean - Exploration
• Ocean - Climate
• Ocean - Ecology
• Ocean - Economy
• Ocean - Ancient oceans
• Ocean - Ocean rowing
• Ocean - Extraterrestrial oceans

Read more here: » Ocean: Encyclopedia - Ocean

Muspelheim ("Flameland"), also called Muspel (Old Norse Múspellsheimr and Múspell, respectively), is the realm of fire in Norse Mythology. It is home to the fire giants, and their master, Surtur. It is fire and the land to the north, Niflheim is ice. The two mixed and created water from the melting ice in Ginnungagap. Sparks from Muspelheim created the planets, comets and stars. Norse mythology ...

Read more here: » Muspelheim: Encyclopedia - Muspelheim

Wikisource has ephemerides of several planets: Ephemeris of Sun Ephemeris of Moon Ephemeris of Mercury Ephemeris of Venus Ephemeris of Mars Ephemeris of Jupiter Ephemeris of Saturn Ephemeris of Uranus Ephemeris of Neptune Ephemeris of Pluto Ephemeris of Ceres Ephemeris of Pallas Ephe ...

Read more here: » Ephemeris: Encyclopedia - Ephemeris