Orbital Neoplasms: Neoplasms of the bony orbit and contents except the eyeball.Orbital Diseases: Diseases of the bony orbit and contents except the eyeball.Arctic Regions: The Arctic Ocean and the lands in it and adjacent to it. It includes Point Barrow, Alaska, most of the Franklin District in Canada, two thirds of Greenland, Svalbard, Franz Josef Land, Lapland, Novaya Zemlya, and Northern Siberia. (Webster's New Geographical Dictionary, 1988, p66)Exophthalmos: Abnormal protrusion of both eyes; may be caused by endocrine gland malfunction, malignancy, injury, or paralysis of the extrinsic muscles of the eye.Setaria Nematode: A genus of parasitic nematodes found in the peritoneal cavity of wild or domestic cattle or equines.Paleography: The study of ancient inscriptions and modes of writing. It includes the deciphering of manuscripts and other forms to determine their date, provenance, etc. (Webster's 1st ed)Orbit Evisceration: The surgical removal of the contents of the orbit. This includes the eyeball, blood vessels, muscles, fat, nerve supply, and periosteum. It should be differentiated from EYE EVISCERATION which removes the inner contents of the eye, leaving the sclera intact.Oculomotor Muscles: The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.Setariasis: Infection with nematodes of the genus Setaria. This condition is usually seen in cattle and equines and is of little pathogenic significance, although migration of the worm to the eye may lead to blindness.SvalbardCold Climate: A climate characterized by COLD TEMPERATURE for a majority of the time during the year.Graves Ophthalmopathy: An autoimmune disorder of the EYE, occurring in patients with Graves disease. Subtypes include congestive (inflammation of the orbital connective tissue), myopathic (swelling and dysfunction of the extraocular muscles), and mixed congestive-myopathic ophthalmopathy.Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Cyperaceae: The sedge plant family of the order Cyperales, subclass Commelinidae, class Liliopsida (monocotyledons)Siberia: A region, north-central Asia, largely in Russia. It extends from the Ural Mountains to the Pacific Ocean and from the Arctic Ocean to central Kazakhstan and the borders of China and Mongolia.Eye Foreign Bodies: Inanimate objects that become enclosed in the eye.Extraterrestrial Environment: The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.Eye Neoplasms: Tumors or cancer of the EYE.Space Flight: Travel beyond the earth's atmosphere.Orbital Pseudotumor: A nonspecific tumor-like inflammatory lesion in the ORBIT of the eye. It is usually composed of mature LYMPHOCYTES; PLASMA CELLS; MACROPHAGES; LEUKOCYTES with varying degrees of FIBROSIS. Orbital pseudotumors are often associated with inflammation of the extraocular muscles (ORBITAL MYOSITIS) or inflammation of the lacrimal glands (DACRYOADENITIS).Eye Enucleation: The surgical removal of the eyeball leaving the eye muscles and remaining orbital contents intact.Enophthalmos: Recession of the eyeball into the orbit.Orbital Implants: Rounded objects made of coral, teflon, or alloplastic polymer and covered with sclera, and which are implanted in the orbit following enucleation. An artificial eye (EYE, ARTIFICIAL) is usually attached to the anterior of the orbital implant for cosmetic purposes.Diplopia: A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include REFRACTIVE ERRORS; STRABISMUS; OCULOMOTOR NERVE DISEASES; TROCHLEAR NERVE DISEASES; ABDUCENS NERVE DISEASES; and diseases of the BRAIN STEM and OCCIPITAL LOBE.Lacrimal Apparatus Diseases: Diseases of the lacrimal apparatus.Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Reindeer: A genus of deer, Rangifer, that inhabits the northern parts of Europe, Asia, and America. Caribou is the North American name; reindeer, the European. They are often domesticated and used, especially in Lapland, for drawing sleds and as a source of food. Rangifer is the only genus of the deer family in which both sexes are antlered. Most caribou inhabit arctic tundra and surrounding arboreal coniferous forests and most have seasonal shifts in migration. They are hunted extensively for their meat, skin, antlers, and other parts. (From Webster, 3d ed; Walker's Mammals of the World, 5th ed, p1397)Earth (Planet): Planet that is the third in order from the sun. It is one of the four inner or terrestrial planets of the SOLAR SYSTEM.Anophthalmos: Congenital absence of the eye or eyes.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Planets: Celestial bodies orbiting around the sun or other stars.Plant Development: Processes orchestrated or driven by a plethora of genes, plant hormones, and inherent biological timing mechanisms facilitated by secondary molecules, which result in the systematic transformation of plants and plant parts, from one stage of maturity to another.AlaskaDecalcification, Pathologic: The loss of calcium salts from bones and teeth. Bacteria may be responsible for this occurrence in teeth. Old age may be a factor contributing to calcium loss, as is the presence of diseases such as rheumatoid arthritis.Frontal Sinus: One of the paired, but seldom symmetrical, air spaces located between the inner and outer compact layers of the FRONTAL BONE in the forehead.Eye Injuries: Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.Eye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.Eye, Artificial: A ready-made or custom-made prosthesis of glass or plastic shaped and colored to resemble the anterior portion of a normal eye and used for cosmetic reasons. It is attached to the anterior portion of an orbital implant (ORBITAL IMPLANTS) which is placed in the socket of an enucleated or eviscerated eye. (From Dorland, 28th ed)Facial Injuries: General or unspecified injuries to the soft tissue or bony portions of the face.Retrobulbar Hemorrhage: Hemorrhage within the orbital cavity, posterior to the eyeball.Exobiology: The interdisciplinary science that studies evolutionary biology, including the origin and evolution of the major elements required for life, their processing in the interstellar medium and in protostellar systems. This field also includes the study of chemical evolution and the subsequent interactions between evolving biota and planetary evolution as well as the field of biology that deals with the study of extraterrestrial life.Climate Change: Any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). It may result from natural factors such as changes in the sun's intensity, natural processes within the climate system such as changes in ocean circulation, or human activities.Snow: Frozen water crystals that fall from the ATMOSPHERE.Spacecraft: Devices, manned and unmanned, which are designed to be placed into an orbit about the Earth or into a trajectory to another celestial body. (NASA Thesaurus, 1988)Oculomotor Nerve: The 3d cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain.Yukon Territory: A territory of northwest Canada, bounded on the north by the Arctic Ocean, on the south by British Columbia, and on the west by Alaska. Its capital is Whitehorse. It takes its name from the Yukon River, the Indian yu-kun-ah, meaning big river. (From Webster's New Geographical Dictionary, 1988, p1367 & Room, Brewer's Dictionary of Names, 1992, p608)Salix: A plant genus of the family SALICACEAE. Members contain salicin, which yields SALICYLIC ACID.Agricultural Irrigation: The routing of water to open or closed areas where it is used for agricultural purposes.Eyelid Neoplasms: Tumors of cancer of the EYELIDS.Laron Syndrome: An autosomal recessive disorder characterized by short stature, defective GROWTH HORMONE RECEPTOR, and failure to generate INSULIN-LIKE GROWTH FACTOR I by GROWTH HORMONE. Laron syndrome is not a form of primary pituitary dwarfism (GROWTH HORMONE DEFICIENCY DWARFISM) but the result of mutation of the human GHR gene on chromosome 5.Explosive Agents: Substances that are energetically unstable and can produce a sudden expansion of the material, called an explosion, which is accompanied by heat, pressure and noise. Other things which have been described as explosive that are not included here are explosive action of laser heating, human performance, sudden epidemiological outbreaks, or fast cell growth.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Hemangioma, Cavernous: A vascular anomaly that is a collection of tortuous BLOOD VESSELS and connective tissue. This tumor-like mass with the large vascular space is filled with blood and usually appears as a strawberry-like lesion in the subcutaneous areas of the face, extremities, or other regions of the body including the central nervous system.Skull Neoplasms: Neoplasms of the bony part of the skull.Sphenoid Bone: An irregular unpaired bone situated at the SKULL BASE and wedged between the frontal, temporal, and occipital bones (FRONTAL BONE; TEMPORAL BONE; OCCIPITAL BONE). Sphenoid bone consists of a median body and three pairs of processes resembling a bat with spread wings. The body is hollowed out in its inferior to form two large cavities (SPHENOID SINUS).Pedobacter: A genus of gram-negative, aerobic, rod-shaped bacteria in the family Sphingobacteriaceae. They exhibit gliding motility.Haemosporida: An order of heteroxenous protozoa in which the macrogamete and microgamont develop independently. A conoid is usually absent.Skull: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.Eyelids: Each of the upper and lower folds of SKIN which cover the EYE when closed.Mucocele: A retention cyst of the salivary gland, lacrimal sac, paranasal sinuses, appendix, or gallbladder. (Stedman, 26th ed)Conjunctival DiseasesParanasal Sinus Diseases: Diseases affecting or involving the PARANASAL SINUSES and generally manifesting as inflammation, abscesses, cysts, or tumors.Eye Movements: Voluntary or reflex-controlled movements of the eye.Maxillary Sinus: The air space located in the body of the MAXILLARY BONE near each cheek. Each maxillary sinus communicates with the middle passage (meatus) of the NASAL CAVITY on the same side.Tarsiidae: The single family of PRIMATES in the infraorder TARSII, suborder HAPLORHINI. It is comprised of one genus, Tarsius, that inhabits southern Sumatra, Borneo, Sulawesi, and the Philippines.Optic Nerve: The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.Anseriformes: An order of BIRDS comprising the waterfowl, particularly DUCKS; GEESE; swans; and screamers.Eye Diseases: Diseases affecting the eye.Eye Injuries, Penetrating: Deeply perforating or puncturing type intraocular injuries.Biomass: Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.Cosmic Dust: Finely divided solid matter with particle sizes smaller than a micrometeorite, thus with diameters much smaller than a millimeter, moving in interplanetary space. (NASA Thesaurus, 1994)Paranasal Sinuses: Air-filled spaces located within the bones around the NASAL CAVITY. They are extensions of the nasal cavity and lined by the ciliated NASAL MUCOSA. Each sinus is named for the cranial bone in which it is located, such as the ETHMOID SINUS; the FRONTAL SINUS; the MAXILLARY SINUS; and the SPHENOID SINUS.Cranial Fossa, Anterior: The compartment containing the inferior part and anterior extremities of the frontal lobes (FRONTAL LOBE) of the cerebral hemispheres. It is formed mainly by orbital parts of the FRONTAL BONE and the lesser wings of the SPHENOID BONE.FiresOphthalmoplegia: Paralysis of one or more of the ocular muscles due to disorders of the eye muscles, neuromuscular junction, supporting soft tissue, tendons, or innervation to the muscles.Astronomy: The science concerned with celestial bodies and the observation and interpretation of the radiation received in the vicinity of the earth from the component parts of the universe (McGraw Hill Dictionary of Scientific and Technical Terms, 5th ed)Orbital Cellulitis: Inflammation of the loose connective tissues around the ORBIT, bony structure around the eyeball. It is characterized by PAIN; EDEMA of the CONJUNCTIVA; swelling of the EYELIDS; EXOPHTHALMOS; limited eye movement; and loss of vision.Lacrimal Apparatus: The tear-forming and tear-conducting system which includes the lacrimal glands, eyelid margins, conjunctival sac, and the tear drainage system.Jupiter: The fifth planet in order from the sun. It is one of the five outer planets of the solar system. Its sixteen natural satellites include Callisto, Europa, Ganymede, and Io.Dacryocystitis: Inflammation of the lacrimal sac. (Dorland, 27th ed)Cosmic Radiation: High-energy radiation or particles from extraterrestrial space that strike the earth, its atmosphere, or spacecraft and may create secondary radiation as a result of collisions with the atmosphere or spacecraft.Arvicolinae: A subfamily of MURIDAE found nearly world-wide and consisting of about 20 genera. Voles, lemmings, and muskrats are members.Weightlessness: Condition in which no acceleration, whether due to gravity or any other force, can be detected by an observer within a system. It also means the absence of weight or the absence of the force of gravity acting on a body. Microgravity, gravitational force between 0 and 10 -6 g, is included here. (From NASA Thesaurus, 1988)Cranial Fossa, Middle: The compartment containing the anterior extremities and half the inferior surface of the temporal lobes (TEMPORAL LOBE) of the cerebral hemispheres. Lying posterior and inferior to the anterior cranial fossa (CRANIAL FOSSA, ANTERIOR), it is formed by part of the TEMPORAL BONE and SPHENOID BONE. It is separated from the posterior cranial fossa (CRANIAL FOSSA, POSTERIOR) by crests formed by the superior borders of the petrous parts of the temporal bones.Saturn: The sixth planet in order from the sun. It is one of the five outer planets of the solar system. Its twelve natural satellites include Phoebe and Titan.Periosteum: Thin outer membrane that surrounds a bone. It contains CONNECTIVE TISSUE, CAPILLARIES, nerves, and a number of cell types.Graves Disease: A common form of hyperthyroidism with a diffuse hyperplastic GOITER. It is an autoimmune disorder that produces antibodies against the THYROID STIMULATING HORMONE RECEPTOR. These autoantibodies activate the TSH receptor, thereby stimulating the THYROID GLAND and hypersecretion of THYROID HORMONES. These autoantibodies can also affect the eyes (GRAVES OPHTHALMOPATHY) and the skin (Graves dermopathy).Mesenchymoma: A mixed mesenchymal tumor composed of two or more mesodermal cellular elements not commonly associated, not counting fibrous tissue as one of the elements. Mesenchymomas are widely distributed in the body and about 75% are malignant. (Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p1866)Facial NeoplasmsBlepharoptosis: Drooping of the upper lid due to deficient development or paralysis of the levator palpebrae muscle.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Eye Infections, Parasitic: Mild to severe infections of the eye and its adjacent structures (adnexa) by adult or larval protozoan or metazoan parasites.Strabismus: Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)Solar System: The group of celestial bodies, including the EARTH, orbiting around and gravitationally bound by the sun. It includes eight planets, one minor planet, and 34 natural satellites, more than 1,000 observed comets, and thousands of lesser bodies known as MINOR PLANETS (asteroids) and METEOROIDS. (From Academic American Encyclopedia, 1983)Conjunctival Neoplasms: Tumors or cancer of the CONJUNCTIVA.Receptors, Thyrotropin: Cell surface proteins that bind pituitary THYROTROPIN (also named thyroid stimulating hormone or TSH) and trigger intracellular changes of the target cells. TSH receptors are present in the nervous system and on target cells in the thyroid gland. Autoantibodies to TSH receptors are implicated in thyroid diseases such as GRAVES DISEASE and Hashimoto disease (THYROIDITIS, AUTOIMMUNE).Craniofacial Dysostosis: Autosomal dominant CRANIOSYNOSTOSIS with shallow ORBITS; EXOPHTHALMOS; and maxillary hypoplasia.Ophthalmic Artery: Artery originating from the internal carotid artery and distributing to the eye, orbit and adjacent facial structures.Trinitrotoluene: A 2,4,6-trinitrotoluene, which is an explosive chemical that can cause skin irritation and other toxic consequences.Connective Tissue: Tissue that supports and binds other tissues. It consists of CONNECTIVE TISSUE CELLS embedded in a large amount of EXTRACELLULAR MATRIX.Climate: The longterm manifestations of WEATHER. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Cysts: Any fluid-filled closed cavity or sac that is lined by an EPITHELIUM. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Craniotomy: Any operation on the cranium or incision into the cranium. (Dorland, 28th ed)Optic Nerve Neoplasms: Benign and malignant neoplasms that arise from the optic nerve or its sheath. OPTIC NERVE GLIOMA is the most common histologic type. Optic nerve neoplasms tend to cause unilateral visual loss and an afferent pupillary defect and may spread via neural pathways to the brain.Evolution, Chemical: Chemical and physical transformation of the biogenic elements from their nucleosynthesis in stars to their incorporation and subsequent modification in planetary bodies and terrestrial biochemistry. It includes the mechanism of incorporation of biogenic elements into complex molecules and molecular systems, leading up to the origin of life.Ice: The solid substance formed by the FREEZING of water.Solitary Fibrous Tumors: Rare neoplasms of mesenchymal origin, usually benign, and most commonly involving the PLEURA (see SOLITARY FIBROUS TUMOR, PLEURAL). They also are found in extrapleural sites.Birds: Warm-blooded VERTEBRATES possessing FEATHERS and belonging to the class Aves.Evolution, Planetary: Creation and development of bodies within solar systems, includes study of early planetary geology.Eyelid DiseasesSoil: The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Maxillary Sinus Neoplasms: Tumors or cancer of the MAXILLARY SINUS. They represent the majority of paranasal neoplasms.Esotropia: A form of ocular misalignment characterized by an excessive convergence of the visual axes, resulting in a "cross-eye" appearance. An example of this condition occurs when paralysis of the lateral rectus muscle causes an abnormal inward deviation of one eye on attempted gaze.Imaging, Three-Dimensional: The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.Ocular Motility Disorders: Disorders that feature impairment of eye movements as a primary manifestation of disease. These conditions may be divided into infranuclear, nuclear, and supranuclear disorders. Diseases of the eye muscles or oculomotor cranial nerves (III, IV, and VI) are considered infranuclear. Nuclear disorders are caused by disease of the oculomotor, trochlear, or abducens nuclei in the BRAIN STEM. Supranuclear disorders are produced by dysfunction of higher order sensory and motor systems that control eye movements, including neural networks in the CEREBRAL CORTEX; BASAL GANGLIA; CEREBELLUM; and BRAIN STEM. Ocular torticollis refers to a head tilt that is caused by an ocular misalignment. Opsoclonus refers to rapid, conjugate oscillations of the eyes in multiple directions, which may occur as a parainfectious or paraneoplastic condition (e.g., OPSOCLONUS-MYOCLONUS SYNDROME). (Adams et al., Principles of Neurology, 6th ed, p240)Plants: Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.Strepsirhini: A suborder of PRIMATES consisting of the following five families: CHEIROGALEIDAE; Daubentoniidae; Indriidae; LEMURIDAE; and LORISIDAE.Harderian Gland: A sebaceous gland that, in some animals, acts as an accessory to the lacrimal gland. The harderian gland excretes fluid that facilitates movement of the third eyelid.Space Simulation: An environment simulating one or more parameters of the space environment, applied in testing space systems or components. Often, a closed chamber is used, capable of approximating the vacuum and normal environments of space. (From NASA Thesaurus, 1988) This also includes simulated EXTRAVEHICULAR ACTIVITY studies in atmosphere exposure chambers or water tanks.Antiparasitic Agents: Drugs used to treat or prevent parasitic infections.Cavernous Sinus: An irregularly shaped venous space in the dura mater at either side of the sphenoid bone.Moon: The natural satellite of the planet Earth. It includes the lunar cycles or phases, the lunar month, lunar landscapes, geography, and soil.Panophthalmitis: Acute suppurative inflammation of the inner eye with necrosis of the sclera (and sometimes the cornea) and extension of the inflammation into the orbit. Pain may be severe and the globe may rupture. In endophthalmitis the globe does not rupture.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Hidrocystoma: A cystic form of sweat gland adenoma (ADENOMA, SWEAT GLAND). It is produced by the cystic proliferation of apocrine secretory glands. It is not uncommon, occurring in adult life in no particular age group, with males and females equally affected. The commonest site is around the eye, particularly lateral to the outer canthus. It is cured by surgical removal. (Stedman, 25th ed; Rook et al., Textbook of Dermatology, 4th ed, p2410)Astronauts: Members of spacecraft crew including those who travel in space, and those in training for space flight. (From Webster, 10th ed; Jane's Aerospace Dictionary, 3d ed)History, Ancient: The period of history before 500 of the common era.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Retinoblastoma: A malignant tumor arising from the nuclear layer of the retina that is the most common primary tumor of the eye in children. The tumor tends to occur in early childhood or infancy and may be present at birth. The majority are sporadic, but the condition may be transmitted as an autosomal dominant trait. Histologic features include dense cellularity, small round polygonal cells, and areas of calcification and necrosis. An abnormal pupil reflex (leukokoria); NYSTAGMUS, PATHOLOGIC; STRABISMUS; and visual loss represent common clinical characteristics of this condition. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, p2104)Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Head Injuries, Penetrating: Head injuries which feature compromise of the skull and dura mater. These may result from gunshot wounds (WOUNDS, GUNSHOT), stab wounds (WOUNDS, STAB), and other forms of trauma.Zygoma: Either of a pair of bones that form the prominent part of the CHEEK and contribute to the ORBIT on each side of the SKULL.Meteoroids: Any solid objects moving in interplanetary space that are smaller than a planet or asteroid but larger than a molecule. Meteorites are any meteoroid that has fallen to a planetary surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Phantoms, Imaging: Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)Life Support Systems: Systems that provide all or most of the items necessary for maintaining life and health. Provisions are made for the supplying of oxygen, food, water, temperature and pressure control, disposition of carbon dioxide and body waste. The milieu may be a spacecraft, a submarine, or the surface of the moon. In medical care, usually under hospital conditions, LIFE SUPPORT CARE is available. (From Webster's New Collegiate Dictionary)Environmental Monitoring: The monitoring of the level of toxins, chemical pollutants, microbial contaminants, or other harmful substances in the environment (soil, air, and water), workplace, or in the bodies of people and animals present in that environment.Fossils: Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.Greenhouse Effect: The effect of GLOBAL WARMING and the resulting increase in world temperatures. The predicted health effects of such long-term climatic change include increased incidence of respiratory, water-borne, and vector-borne diseases.Cellulitis: An acute, diffuse, and suppurative inflammation of loose connective tissue, particularly the deep subcutaneous tissues, and sometimes muscle, which is most commonly seen as a result of infection of a wound, ulcer, or other skin lesions.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Eosinophilic Granuloma: The most benign and common form of Langerhans-cell histiocytosis which involves localized nodular lesions predominantly of the bones but also of the gastric mucosa, small intestine, lungs, or skin, with infiltration by EOSINOPHILS.Head: The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.Microphthalmos: Congenital or developmental anomaly in which the eyeballs are abnormally small.Biodiversity: The variety of all native living organisms and their various forms and interrelationships.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Eye Evisceration: The surgical removal of the inner contents of the eye, leaving the sclera intact. It should be differentiated from ORBIT EVISCERATION which removes the entire contents of the orbit, including eyeball, blood vessels, muscles, fat, nerve supply, and periosteum.Sweat Gland NeoplasmsBlindness: The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.Frontal Sinusitis: Inflammation of the NASAL MUCOSA in the FRONTAL SINUS. In many cases, it is caused by an infection of the bacteria STREPTOCOCCUS PNEUMONIAE or HAEMOPHILUS INFLUENZAE.Foreign Bodies: Inanimate objects that become enclosed in the body.Oculomotor Nerve Diseases: Diseases of the oculomotor nerve or nucleus that result in weakness or paralysis of the superior rectus, inferior rectus, medial rectus, inferior oblique, or levator palpebrae muscles, or impaired parasympathetic innervation to the pupil. With a complete oculomotor palsy, the eyelid will be paralyzed, the eye will be in an abducted and inferior position, and the pupil will be markedly dilated. Commonly associated conditions include neoplasms, CRANIOCEREBRAL TRAUMA, ischemia (especially in association with DIABETES MELLITUS), and aneurysmal compression. (From Adams et al., Principles of Neurology, 6th ed, p270)Skull Base Neoplasms: Neoplasms of the base of the skull specifically, differentiated from neoplasms of unspecified sites or bones of the skull (SKULL NEOPLASMS).Maxillary Sinusitis: Inflammation of the NASAL MUCOSA in the MAXILLARY SINUS. In many cases, it is caused by an infection of the bacteria HAEMOPHILUS INFLUENZAE; STREPTOCOCCUS PNEUMONIAE; or STAPHYLOCOCCUS AUREUS.Mucormycosis: Infection in humans and animals caused by any fungus in the order Mucorales (e.g., Absidia, Mucor, Rhizopus etc.) There are many clinical types associated with infection of the central nervous system, lung, gastrointestinal tract, skin, orbit and paranasal sinuses. In humans, it usually occurs as an opportunistic infection in patients with a chronic debilitating disease, particularly uncontrolled diabetes, or who are receiving immunosuppressive agents. (From Dorland, 28th ed)Rhabdomyosarcoma: A malignant solid tumor arising from mesenchymal tissues which normally differentiate to form striated muscle. It can occur in a wide variety of sites. It is divided into four distinct types: pleomorphic, predominantly in male adults; alveolar (RHABDOMYOSARCOMA, ALVEOLAR), mainly in adolescents and young adults; embryonal (RHABDOMYOSARCOMA, EMBRYONAL), predominantly in infants and children; and botryoidal, also in young children. It is one of the most frequently occurring soft tissue sarcomas and the most common in children under 15. (From Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p2186; DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, pp1647-9)Wounds, Gunshot: Disruption of structural continuity of the body as a result of the discharge of firearms.Histiocytosis, Sinus: Benign, non-Langerhans-cell, histiocytic proliferative disorder that primarily affects the lymph nodes. It is often referred to as sinus histiocytosis with massive lymphadenopathy.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Choristoma: A mass of histologically normal tissue present in an abnormal location.Hematoma: A collection of blood outside the BLOOD VESSELS. Hematoma can be localized in an organ, space, or tissue.Models, Theoretical: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Histiocytosis, Langerhans-Cell: A group of disorders resulting from the abnormal proliferation of and tissue infiltration by LANGERHANS CELLS which can be detected by their characteristic Birbeck granules (X bodies), or by monoclonal antibody staining for their surface CD1 ANTIGENS. Langerhans-cell granulomatosis can involve a single organ, or can be a systemic disorder.ExplosionsFresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.Head Movements: Voluntary or involuntary motion of head that may be relative to or independent of body; includes animals and humans.Retinal Neoplasms: Tumors or cancer of the RETINA.Technology, Radiologic: The application of scientific knowledge or technology to the field of radiology. The applications center mostly around x-ray or radioisotopes for diagnostic and therapeutic purposes but the technological applications of any radiation or radiologic procedure is within the scope of radiologic technology.Choroid Neoplasms: Tumors of the choroid; most common intraocular tumors are malignant melanomas of the choroid. These usually occur after puberty and increase in incidence with advancing age. Most malignant melanomas of the uveal tract develop from benign melanomas (nevi).Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Cranial Nerve Diseases: Disorders of one or more of the twelve cranial nerves. With the exception of the optic and olfactory nerves, this includes disorders of the brain stem nuclei from which the cranial nerves originate or terminate.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Cone-Beam Computed Tomography: Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.Optic Nerve Diseases: Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.Models, Anatomic: Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.Blast Injuries: Injuries resulting when a person is struck by particles impelled with violent force from an explosion. Blast causes pulmonary concussion and hemorrhage, laceration of other thoracic and abdominal viscera, ruptured ear drums, and minor effects in the central nervous system. (From Dorland, 27th ed)Reflex, Vestibulo-Ocular: A reflex wherein impulses are conveyed from the cupulas of the SEMICIRCULAR CANALS and from the OTOLITHIC MEMBRANE of the SACCULE AND UTRICLE via the VESTIBULAR NUCLEI of the BRAIN STEM and the median longitudinal fasciculus to the OCULOMOTOR NERVE nuclei. It functions to maintain a stable retinal image during head rotation by generating appropriate compensatory EYE MOVEMENTS.Tomography, Emission-Computed, Single-Photon: A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.Sinusitis: Inflammation of the NASAL MUCOSA in one or more of the PARANASAL SINUSES.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Microtubule-Associated Proteins: High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Wounds, Penetrating: Wounds caused by objects penetrating the skin.Population Dynamics: The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population.Hemangioma, Capillary: A dull red, firm, dome-shaped hemangioma, sharply demarcated from surrounding skin, usually located on the head and neck, which grows rapidly and generally undergoes regression and involution without scarring. It is caused by proliferation of immature capillary vessels in active stroma, and is usually present at birth or occurs within the first two or three months of life. (Dorland, 27th ed)Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Mars: The fourth planet in order from the sun. Its two natural satellites are Deimos and Phobos. It is one of the four inner or terrestrial planets of the solar system.Plant Physiological Phenomena: The physiological processes, properties, and states characteristic of plants.Rotation: Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Meningioma: A relatively common neoplasm of the CENTRAL NERVOUS SYSTEM that arises from arachnoidal cells. The majority are well differentiated vascular tumors which grow slowly and have a low potential to be invasive, although malignant subtypes occur. Meningiomas have a predilection to arise from the parasagittal region, cerebral convexity, sphenoidal ridge, olfactory groove, and SPINAL CANAL. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2056-7)Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Equipment Design: Methods of creating machines and devices.Histiocytoma, Benign Fibrous: A benign tumor composed, wholly or in part, of cells with the morphologic characteristics of HISTIOCYTES and with various fibroblastic components. Fibrous histiocytomas can occur anywhere in the body. When they occur in the skin, they are called dermatofibromas or sclerosing hemangiomas. (From DeVita Jr et al., Cancer: Principles & Practice of Oncology, 5th ed, p1747)Nose Diseases: Disorders of the nose, general or unspecified.Geography: The science dealing with the earth and its life, especially the description of land, sea, and air and the distribution of plant and animal life, including humanity and human industries with reference to the mutual relations of these elements. (From Webster, 3d ed)Sclera: The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea. It is essentially avascular but contains apertures for vessels, lymphatics, and nerves. It receives the tendons of insertion of the extraocular muscles and at the corneoscleral junction contains the canal of Schlemm. (From Cline et al., Dictionary of Visual Science, 4th ed)Fibrous Dysplasia, Monostotic: FIBROUS DYSPLASIA OF BONE involving only one bone.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Neurofibroma, Plexiform: A type of neurofibroma manifesting as a diffuse overgrowth of subcutaneous tissue, usually involving the face, scalp, neck, and chest but occasionally occurring in the abdomen or pelvis. The tumors tend to progress, and may extend along nerve roots to eventually involve the spinal roots and spinal cord. This process is almost always a manifestation of NEUROFIBROMATOSIS 1. (From Adams et al., Principles of Neurology, 6th ed, p1016; J Pediatr 1997 Nov;131(5):678-82)
Molniya orbit - A highly elliptical orbit with inclination of 63.4° and orbital period of ½ of a sidereal day (roughly 12 hours ... Tundra orbit - A highly elliptical orbit with inclination of 63.4° and orbital period of one sidereal day (roughly 24 hours). ... Geostationary orbit (GSO): A geosynchronous orbit with an inclination of zero. To an observer on the ground this satellite ... Spaceflight portal Earth's orbit List of orbits Astrodynamics Celestial sphere Heliocentric orbit Areosynchronous satellite ...
... but not all geosynchronous orbits are geostationary." Tundra orbit: A synchronous but highly elliptic orbit with significant ... Heliocentric orbit: An orbit around the Sun. In the Solar System, all planets, comets, and asteroids are in such orbits, as are ... Molniya orbit: A semi-synchronous variation of a Tundra orbit. For Earth this means an orbital period of just under 12 hours. ... in which natural drifting due to the central body's shape has been minimized by careful selection of the orbital parameters. ...
"Stabilization of heliosynchronous orbits of an Earth's artificial satellite by solar pressure". Cosmic Research. 37 (4): 393- ... where a is the semi-major axis of the orbit and μ is the standard gravitational parameter of the planet (398600.440 km3/s2 for ... Elliptical / Highly elliptical. *Escape. *Horseshoe. *Hyperbolic trajectory. *Inclined / Non-inclined. *Lagrangian point ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Parameters that uniquely identify a specific orbit. Orbital elements are the parameters required to uniquely identify a ... Note that non-elliptic trajectories also exist, but are not closed, and are thus not orbits. If the eccentricity is greater ... and for satellites in solar orbits it is the ecliptic plane. The intersection is called the line of nodes, as it connects the ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Gravitational orbits. Types. General. *Box. *Capture. *Circular. *Elliptical / Highly elliptical. *Escape. *Graveyard ... Lunar and solar eclipses can occur when the nodes align with the Sun, roughly every 173.3 days. Lunar orbit inclination also ... Geostationary. *Sun-synchronous. *Low Earth. *Medium Earth. *High Earth. *Molniya. *Near-equatorial ... Not to be confused with Lunar orbit (the orbit of an object around the Moon).. Orbit of the Moon ...
List of orbits. *Medium Earth orbit (MEO). *High Earth orbit (HEO). *Highly elliptical orbit (HEO) ... sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit ... "LEO parameters". www.spaceacademy.net.au. Retrieved 2015-06-12.. *^ Swinerd, Graham (2008). How Spacecraft Fly. Praxis ... Molniya. *Near-equatorial. *Orbit of the Moon. *Polar. *Tundra. About other points. *Areosynchronous ...
The LEO region is defined by some sources as the region in space that LEO orbits occupy.[7][8][9][10] Some highly elliptical ... sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit ... "LEO parameters". www.spaceacademy.net.au. Retrieved 2015-06-12.. *^ Swinerd, Graham (2008). How Spacecraft Fly. Praxis ... Molniya. *Near-equatorial. *Orbit of the Moon. *Polar. *Tundra. About other points. *Areosynchronous ...
The moons of planets in the Solar System, by contrast, are not in heliocentric orbits, as they orbit their respective planet ( ... Transfer injections can place spacecraft into either a Hohmann transfer orbit or bi-elliptic transfer orbit. Trans-Mars ... Geostationary. *Sun-synchronous. *Low Earth. *Medium Earth. *High Earth. *Molniya. *Near-equatorial ... A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually ...
Gravitational orbits. Types. General. *Box. *Capture. *Circular. *Elliptical / Highly elliptical. *Escape. *Horseshoe ... The next mission to use a halo orbit was Solar and Heliospheric Observatory (SOHO), a joint ESA and NASA mission to study the ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ... Halo orbits exist in any three-body system, e.g., the Sun-Earth-Orbiting Satellite system or the Earth-Moon-Orbiting Satellite ...
... s can affect all parts of the eye, and can be a benign tumor or a malignant tumor (cancer). Eye cancers can be primary (starts within the eye) or metastatic cancer (spread to the eye from another organ). The two most common cancers that spread to the eye from another organ are breast cancer and lung cancer. Other less common sites of origin include the prostate, kidney, thyroid, skin, colon and blood or bone marrow. Tumors in the eye and orbit can be benign like dermoid cysts, or malignant like rhabdomyosarcoma and retinoblastoma. The most common eyelid tumor is called basal cell carcinoma. This tumor can grow around the eye but rarely spreads to other parts of the body. Other types of common eyelid cancers include squamous carcinoma, sebaceous carcinoma and malignant melanoma. The most common orbital malignancy is orbital lymphoma. This tumor can be diagnosed by biopsy with histopathologic and ...
Idiopathic orbital inflammatory (IOI) disease, or orbital pseudotumor, refers to a marginated mass-like enhancing soft tissue involving any area of the orbit. It is the most common painful orbital mass in the adult population, and is associated with proptosis, cranial nerve palsy (Tolosa-Hunt syndrome), uveitis, and retinal detachment. Idiopathic orbital inflammatory syndrome, also known as orbital pseudotumor, was first described by Gleason in 1903 and by Busse and Hochhmein. It was then characterized as a distinct entity in 1905 by Birch-Hirschfeld. It is a benign, nongranulomatous orbital inflammatory process characterized by extraocular orbital and adnexal inflammation with no known local or systemic cause. Its diagnosis is of exclusion ...
... is inflammation of eye tissues behind the orbital septum. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. It may also occur after trauma. When it affects the rear of the eye, it is known as retro-orbital cellulitis. It should not be confused with periorbital cellulitis, which refers to cellulitis anterior to the septum. Common signs and symptoms of orbital cellulitis include pain with eye movement, sudden vision loss, chemosis, bulging of the infected eye, and limited eye movement. Along with these symptoms, patients typically have redness and swelling of the eyelid, pain, discharge, inability to open the eye, occasional fever and lethargy. It is usually caused by a previous sinusitis. Other causes include infection of nearby structures, trauma and previous surgery. ...
The orbital septum (Palpebral fascia) is a membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids. In the upper eyelid, the orbital septum blends with the tendon of the levator palpebrae superioris, and in the lower eyelid with the tarsal plate. When the eyes are closed, the whole orbital opening is covered by the septum and tarsi. Medially it is thin, and, becoming separated from the medial palpebral ligament, attaches to the lacrimal bone at its posterior crest. The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves. The septum is perforated by the vessels and nerves which pass from the orbital ...
A geostationary orbit can be achieved only at an altitude very close to 35,786 km (22,236 mi) and directly above the equator. This equates to an orbital velocity of 3.07 km/s (1.91 mi/s) and an orbital period of 1,436 minutes, which equates to almost exactly one sidereal day (23.934461223 hours). This ensures that the satellite will match the Earth's rotational period and has a stationary footprint on the ground. All geostationary satellites have to be located on this ring. A combination of lunar gravity, solar gravity, and the flattening of the Earth at its poles causes a precession motion of the orbital plane of any geostationary object, with an orbital period of about 53 years and an initial inclination gradient of about 0.85° per year, achieving a maximal inclination of ...
The state of an orbiting body at any given time is defined by the orbiting body's position and velocity with respect to the central body, which can be represented by the three-dimensional Cartesian coordinates (position of the orbiting body represented by x, y, and z) and the similar Cartesian components of the orbiting body's velocity. This set of six variables, together with time, are called the orbital state vectors. Given the masses of the two bodies they determine the full orbit. The two most general cases with these 6 degrees of freedom are the elliptic and the hyperbolic orbit. Special cases with fewer degrees of freedom are the circular and parabolic orbit. Because at least six variables are absolutely required to completely ...
As an example, for a = 7200 km (the spacecraft about 800 km over the Earth surface) one gets with this formula a Sun-synchronous inclination of 98.696°. Note that according to this approximation cos i equals −1 when the semi-major axis equals 12352 km, which means that only smaller orbits can be Sun-synchronous. The period can be in the range from 88 minutes for a very low orbit (a = 6554 km, i = 96°) to 3.8 hours (a = 12352 km, but this orbit would be equatorial with i = 180°). A period longer than 3.8 hours may be possible by using an eccentric orbit with p , 12352 km but a , 12352 km. If one wants a satellite to fly over some given spot on Earth every day at the same hour, it can do between 7 and 16 orbits per day, as shown in the following table. (The table has been calculated assuming the periods given. The ...
thus, the orbital parameters of the planets are given in heliocentric terms. The difference between the primocentric and "absolute" orbits may best be illustrated by looking at the Earth-Moon system. The mass ratio in this case is 81.30059. The Earth-Moon characteristic distance, the semi-major axis of the geocentric lunar orbit, is 384,400 km. (Given the lunar orbit's eccentricity e = 0.0549, its semi-minor axis is 383,800 km. Thus the Moon's orbit is almost circular.) The barycentric lunar orbit, on the other hand, has a semi-major axis of 379,700 km, the Earth's counter-orbit taking up the difference, 4,700 km. The Moon's average barycentric orbital speed is 1.010 km/s, whilst the Earth's is 0.012 km/s. The total of these ...
... are the adnexa of the eye, including the eyebrow, eyelids, and lacrimal apparatus. One source defines "ocular adnexa" as the orbit, conjunctiva, and eyelids. Knowles, Daniel M. (2001). Neoplastic hematopathology. Hagerstwon, MD: Lippincott Williams & Wilkins. p. 1303. ISBN 0-683-30246-9 ...
thus, the orbital parameters of the planets are given in heliocentric terms. The difference between the primocentric and "absolute" orbits may best be illustrated by looking at the Earth-Moon system. The mass ratio in this case is 7001813005900000000♠81.30059. The Earth-Moon characteristic distance, the semi-major axis of the geocentric lunar orbit, is 384,400 km. The barycentric lunar orbit, on the other hand, has a semi-major axis of 379,700 km, the Earth's counter-orbit taking up the difference, 4,700 km. The Moon's average barycentric orbital speed is 1.010 km/s, whilst the Earth's is 0.012 km/s. The total of these speeds gives a geocentric lunar average orbital speed of 1.022 km/s; the same value may be obtained by considering just the geocentric ...
The first appearance of a geostationary orbit in popular literature was in October, 1942, in the first Venus Equilateral story by George O. Smith,[2] but Smith did not go into details. British science fiction author Arthur C. Clarke popularised and expanded the concept in a 1945 paper entitled "Extra-Terrestrial Relays - Can Rocket Stations Give Worldwide Radio Coverage?", published in Wireless World magazine. Clarke acknowledged the connection in his introduction to The Complete Venus Equilateral.[3] The orbit, which Clarke first described as useful for broadcast and relay communications satellites,[4] is sometimes called the Clarke Orbit.[5] Similarly, the collection of artificial satellites in this orbit is known as the Clarke Belt.[6]. The first geostationary satellite was designed by Harold Rosen while he was working at Hughes Aircraft ...
This template allows AstRoBot to update orbital elements automatically, using data from the Heavens-Above and n2yo websites. (Note that due to recent changes to the Heavens Above website, future support for this source may be discontinued). Do not use this template on articles for spacecraft which are not currently in Earth orbit. Please read the instructions fully before setting up automatic updates. Consider discussing updates on the article's talk page or at the WikiProject talk page beforehand to ensure AstRoBot is suitable for that article. ...
Vez S-O je dolga 149 pm, kar je nekoliko manj, kot bi pričakovali, saj je vez S-OH v žveplovi kislini dolga 157 pm. Sulfatni ion ima po teoriji o odboju elektronskega para valenčne orbitale (VSEPR) [2] obliko tetraedra. Obliko vezi v sulfatnem ionu je prvi predlagal Gilbert Lewis leta 1916. Opisal jih je z elektronskimi okteti okrog vsakega atoma, se pravi brez dvojnih vezi, in s formalnim nabojem žveplovega atoma 2+.[3] Linus Pauling je za opis sulfatnega iona uporabil teorijo valenčne vezi in predpostavil, da ima najpomembnejša resonančna zgradba dve π vezi, kateri tvorijo elektroni z d orbital. Njegov zaključek je bil, da je naboj žvepla skladno s principom električne nevtralnosti zato zmanjšan.[4] Skrajšanje vezi na 149 pm je pripisal dvojni vezi. Paulingova uvedba d orbital je izzvala polemiko o relativni pomembnosti π vezi in polarnosti (elektrostatskega privlaka) pri skrajšanju vezi S-O. Rezultat ...
Molniya orbit - A highly elliptical orbit with inclination of 63.4° and orbital period of ½ of a sidereal day (roughly 12 hours ... Tundra orbit - A highly elliptical orbit with inclination of 63.4° and orbital period of one sidereal day (roughly 24 hours). ... Geostationary orbit (GSO): A geosynchronous orbit with an inclination of zero. To an observer on the ground this satellite ... Spaceflight portal Earths orbit List of orbits Astrodynamics Celestial sphere Heliocentric orbit Areosynchronous satellite ...
... but not all geosynchronous orbits are geostationary." Tundra orbit: A synchronous but highly elliptic orbit with significant ... Heliocentric orbit: An orbit around the Sun. In the Solar System, all planets, comets, and asteroids are in such orbits, as are ... Molniya orbit: A semi-synchronous variation of a Tundra orbit. For Earth this means an orbital period of just under 12 hours. ... in which natural drifting due to the central bodys shape has been minimized by careful selection of the orbital parameters. ...
... along an elliptical path, with the large body being located at one of the ellipse foci ... A small body in space orbits a large one (like a planet around the sun) ... Examples of elliptic orbits include: Hohmann transfer orbit, Molniya orbit and tundra orbit. ... 6 Orbital parameters. *7 Solar system. *8 Radial elliptic trajectory. *9 History ...
"Stabilization of heliosynchronous orbits of an Earths artificial satellite by solar pressure". Cosmic Research. 37 (4): 393- ... where a is the semi-major axis of the orbit and μ is the standard gravitational parameter of the planet (398600.440 km3/s2 for ... Elliptical / Highly elliptical. *Escape. *Horseshoe. *Hyperbolic trajectory. *Inclined / Non-inclined. *Lagrangian point ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Parameters that uniquely identify a specific orbit. Orbital elements are the parameters required to uniquely identify a ... Note that non-elliptic trajectories also exist, but are not closed, and are thus not orbits. If the eccentricity is greater ... and for satellites in solar orbits it is the ecliptic plane. The intersection is called the line of nodes, as it connects the ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Transfer orbits are usually elliptical orbits that allow spacecraft to move from one (usually substantially circular) orbit to ... is often termed the standard gravitational parameter, which has a different value for every planet or moon in the Solar System ... these highly perturbative, even chaotic, orbital trajectories in principle need no fuel beyond that needed to reach the ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Due to their inherent instability, geostationary orbits will eventually become inclined if they are not corrected using ... causing the satellite to rise over a fixed location on the earths surface at the same mean solar time every day. ... Elliptical / Highly elliptical *Escape. *Graveyard. *Horseshoe. *Hyperbolic trajectory. * Inclined / Non-inclined *Osculating ... Molniya. *Near-equatorial. *Orbit of the Moon. *Polar. *Tundra. About other points. *Areosynchronous ...
... the eccentric anomaly is an angular parameter that defines the position of a body that is moving along an elliptic Kepler orbit ... 1.68". Satellites: orbits and missions. Springer. p. 21. ISBN 2-287-21317-1. .. ... Murray, Carl D.; & Dermott, Stanley F. (1999); Solar System Dynamics, Cambridge University Press, Cambridge, GB ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ...
Arctic Communications System Utilizing Satellites in Highly Elliptical Orbits, Lars Løge - Section 3.1, Page 17 ... Peter Goldreich published a classic paper on the evolution of the moons orbit and on the orbits of other moons in the solar ... Geostationary transfer. *Graveyard. *High Earth. *Low Earth. *Medium Earth. *Molniya. *Near-equatorial ... Orbits. The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the ...
  • Newton's method of successive approximation was formalised into an analytic method by Euler in 1744, whose work was in turn generalised to elliptical and hyperbolic orbits by Lambert in 1761-1777. (rug.nl)
  • Thus one cannot move from one circular orbit to another with only one brief application of thrust. (rug.nl)
  • More technically, it is an orbit arranged so that it precesses through one complete revolution each year, so it always maintains the same relationship with the Sun. (wikipedia.org)
  • Special cases of the Sun-synchronous orbit are the noon/midnight orbit , where the local mean solar time of passage for equatorial latitudes is around noon or midnight, and the dawn/dusk orbit , where the local mean solar time of passage for equatorial latitudes is around sunrise or sunset, so that the satellite rides the terminator between day and night. (wikipedia.org)
  • A satellite is said to occupy an inclined orbit around Earth if the orbit exhibits an angle other than 0° to the equatorial plane . (hitchhikersgui.de)
  • The flight path angle is the angle between the orbiting body's velocity vector (= the vector tangent to the instantaneous orbit) and the local horizontal. (academic.ru)
  • The state of an orbiting body at any given time is defined by the orbiting body's position and velocity with respect to the central body, which can be represented by the three-dimensional Cartesian coordinates (position of the orbiting body represented by x, y, and z) and the similar Cartesian components of the orbiting body's velocity. (academic.ru)
  • A satellite orbiting the earth has a tangential velocity and an inward acceleration . (rug.nl)
  • A Sun-synchronous orbit is useful for imaging , spy , and weather satellites , because every time that the satellite is overhead, the surface illumination angle on the planet underneath it will be nearly the same. (wikipedia.org)
  • Without applying force (such as firing a rocket engine), the period and shape of the satellite's orbit won't change. (rug.nl)
  • A property of coelliptic orbits is that the difference in magnitude between aligned radius vectors is nearly the same, regardless of where within the orbits they are positioned. (wikipedia.org)
  • A line drawn from the planet to the satellite sweeps out equal areas in equal times no matter which portion of the orbit is measured. (rug.nl)
  • The LST zones show how the local time beneath the satellite varies at different latitudes and different points on its orbit. (wikipedia.org)
  • A satellite around the almost spherical Venus , for example, will need an outside push to maintain a Sun-synchronous orbit. (wikipedia.org)