GLOSSARY OF TERMS

accretion(lat. accretion increment, increase) - the fall of scattered matter on the surface of a cosmic body - planets, stars, galaxies - under the influence of its attraction. As a rule, a significant proportion of the gravitational energy of the falling matter is released in this case in the form of radiation: the matter heats up when it hits the surface of the star or as a result of mutual friction of the layers in the accretion disk.

Annihilation- a process in which a particle and its antiparticle, colliding, mutually annihilate each other.

Antiparticle - Every particle of matter has a corresponding antiparticle. When a particle and an antiparticle collide, they annihilate, as a result of which energy is released and other particles are born.

Anthropic principle- the statement that all the properties of our Universe (even those not yet discovered) should not contradict the existence in it of those objects that we already know, including humans. There are other formulations of the anthropic principle that do not differ in essence. For example: the properties of the Universe are precisely such, because with its other properties, the emergence of life would be impossible, and, consequently, there would be no observers capable of reflecting on why the properties of the Universe are exactly the way they are.

association stellar- a sparse group of young stars, the age of which usually does not exceed several tens of millions of years. The typical size of a stellar association is 50–100 pc, and the number of observed stars varies from a few to several hundreds.

astronomical unit- the average distance between the centers of the Earth and the Sun, equal to the semi-major axis of the Earth's orbit; 1 a.u. – 149 597 870 ±2 km.

galaxy bulge(English) bulge swelling) - the central, brightest part of the spherical component of a disk galaxy; like the entire spherical component, the bulge consists of old stars moving in elongated orbits. Outwardly, the bulge looks like a central thickening of the disk of the galaxy, in its center there is usually a very dense core.

galaxy bar(English) bar jumper) - an element of the structure of many spiral and irregular galaxies; looks like an elongated compaction of stars and interstellar gas lying in the plane of the disk. The center of the bar usually coincides with the center of the disc. If the galaxy has a bar, then the spiral arms start from its ends, and not from the center of the galaxy.

barster(English) burst flare) - a flaring cosmic source of radiation. One usually speaks of X-ray bursters, whose bursts with a duration of about 10 s and with a characteristic repetition time from minutes to hours are caused by thermonuclear explosions on the surface of neutron stars. Such explosions can occur regularly if, in a close binary system, from the surface of a normal star to neutron star there is a continuous accretion of gas.

white dwarf- a small star, the size of the Earth, but at the same time it is very massive (like the Sun) and therefore very dense: a million times denser than water. It is the collapsed core of a normal star final stage evolution that shed its shell.

Blazars (Lacertids)– a rare type of active galactic nuclei; look like rapidly changing stars.

Shine (brightness) of a star- traditional astronomical terms for the radiation flux coming from the star per unit time per unit of the Earth's surface.

Bolometric magnitude is the radiation flux of the cosmic source summed over all ranges of the spectrum. It is measured using an integrated radiation receiver - a bolometer. With knowledge of the distance to the source, it allows you to calculate the total power of its radiation (luminosity).

Major axis- half the largest diameter of the ellipse.

Big Bang- the first episode in the evolution of our Universe, which took place about 14 billion years ago and marked the beginning of its expansion. According to the currently accepted cosmological theory of the hot Universe, the currently observed mutual removal of galaxies and their clusters reflects the initial, very dense and hot state of matter in the first moments of the existence of the Universe. Even then, the matter in neighboring regions of space should have had high relative velocities, which is still partially manifested in the form of mutual motion of galaxies. The very term "Big Bang" was jokingly proposed by the opponent of this theory, the English astrophysicist Fred Hoyle (1915 - 2001). However, at present, the theory of the hot Universe and the Big Bang is generally accepted.

voids- voids in the Universe with dimensions of tens of megaparsecs.

flashing stars- variable stars, the brightness of which sharply and non-periodically increases for a short time, usually for several minutes. The flare amplitude can reach , although it usually does not exceed .

degenerate star- see white dwarf, neutron star.

Galaxy- a giant system of stars and gas-dust clouds. The word "galaxy" comes from the Greek. galacticos lactic; so called in ancient times Milky Way.

galactic equator- big circle celestial sphere, passing along the Milky Way and equidistant from the galactic poles.

Galilean moons of Jupiter- the four largest satellites discovered by Galileo in 1610 and named by S. Marius "Io", "Europa", "Ganymede" and "Calisto". Their circulation around Jupiter is synchronized under the influence of the tides with their rotation around the axis (like that of the Moon).

Giant- a star of much greater luminosity and size than most stars of the same spectral class. Stars of even greater luminosity and size are called supergiants.

Main sequence– for most main sequence stars, the relationship between mass, radius and luminosity is satisfied. But for stars of small and large masses, and for the most massive ones.

Globules- small gas-dust interstellar clouds containing predominantly molecular hydrogen at a temperature of 10 - 50 K. They are usually visible as dark spots on the bright background of the Milky Way, since the dust present in them completely absorbs the light of the stars lying behind them and bright nebulae.

Gravity lens- any massive body (planet, star) or system of bodies (galaxy, cluster of galaxies) that bends the direction of propagation of radiation with its gravitational field, just as an ordinary lens bends a light beam.

double star- two stars visible in the sky close to each other. If the stars are indeed located side by side and are connected by the force of gravity, then this is a physical double (see Fig. dual system), and if visible side by side as a result of a random projection - an optical double.

Dual system- a system of two stars orbiting around a common center of mass.

Jets– ejections of charged particles from active galactic nuclei in opposite directions, perpendicular to the plane of the accretion disk around the SMBH. Jets are a source of radio emission of a synchrotron nature.

Hertzsprung–Russell diagram- a diagram showing the relationship between the color (or spectral type) and luminosity of stars of various types.

accretion disk A disk of hot gas orbiting a star in a close binary system or around a massive central object at the core of a galaxy. It is formed during the accretion of the matter of a neighboring star or the interstellar matter of a galaxy.

galaxy disk is a flat stellar-gas subsystem of a rotating galaxy. Almost all of the interstellar gas and young stars are concentrated in the disk.

protoplanetary disk- a gas-dust disk rotating around a young star and containing the remnants of protostellar matter. In the event that a star with its radiation and stellar wind does not completely destroy this disk, small protoplanetary bodies are formed in it, some of which then combine into large planets and their satellites, and the other part remains in the form of asteroids and comet nuclei.

Doppler effect- a change in the oscillation frequency or wavelength () perceived by the observer, due to the movement of the wave source and the observer relative to each other. Usually in optical astronomy, the ratio is denoted by a letter and is called "redshift" if the source is moving away from the observer, and "blueshift" if the source is approaching.

eclipsing variable stars are binary stars whose orbital planes are inclined at a small angle to the observer's line of sight, which creates conditions for mutual occultations of stars. At the moments of occultations, when one of the stars blocks the other from the observer, he sees a decrease in the total brightness of the stars.

Star- a celestial body, the luminosity of which is maintained by thermonuclear reactions occurring in its depths.

magnitude- "" (from lat. size value) as an upper italic index to the right of the number. The direction of the magnitude scale is reversed, i.e. the larger the value, the weaker the brilliance of the object. According to Pogson's formula, the ratio of illumination of two stars.

stellar wind is the constant outflow of gas from the star's atmosphere. The flow rate is usually close to second space velocity on the surface of the star.

Zodiac- a zone in the sky with a width on both sides of the ecliptic, containing the visible paths of the Sun, Moon and major planets. It passes through 13 constellations and is divided into 12 signs of the zodiac.

Dwarf - main sequence star, not large sizes(from 1 to 0.01 ) and low luminosity (from 1 to ).

Quasar(English) quasar from quasistellar radio source star-like radio source) is a class of extragalactic objects characterized by very high luminosity and small angular size. The most distant quasars, due to their gigantic luminosity, hundreds of times greater than the luminosity of normal galaxies, are visible at a distance of more than 10 billion light years. years.

Kepler's laws- three laws of planetary motion relative to the Sun; established as a generalization of observational data by I. Kepler at the beginning of the 17th century. 1. The orbit of any planet is an ellipse, in one of the focuses of which is the Sun. 2. The planet moves in such a way that its radius vector covers equal areas in equal time intervals. 3. The squares of the periods of revolution of any two planets are related as the cubes of their average distances from the Sun.

Comet A small Solar System body of ice and dust that typically develops a long tail of gas as it approaches the Sun.

brown dwarf- a cosmic body, occupying in its mass an intermediate position between stars and planets. Brown dwarfs are usually called objects with masses from 0.01 to. The surface temperature of brown dwarfs usually does not exceed 2000 K, so they have a dark red color or generally emit only in the infrared region of the spectrum. The first brown dwarf was discovered in 1996.

cosmic rays- a stream of stable high-energy particles falling to the Earth from world space (primary radiation), as well as those born during interaction with atmospheric matter (secondary radiation).

space speeds are the minimum velocities at which the body can become a satellite of a massive object (the first space velocity), overcome the gravitational attraction of this object and move away from it “to infinity” (second cosmic velocity, or escape velocity) or (for the solar system) overcome the attraction of the Sun and leave the solar system (third cosmic velocity). At the surface of the Earth, the second space velocity is 11.2 km / s, at the surface of the Sun 620 km / s, in the Galaxy (in the region of the orbit of the Sun) - about 400 km / s.

Hubble Space Telescope - automatic extra-atmospheric observatory of NASA (USA) and the European Agency, operating in near-Earth orbit at an altitude of about 600 km. Its telescope with a diameter of 2.4 m takes images in the optical and ultraviolet ranges of the spectrum with angular resolution. It is planned that its work will last until 2013.

Cosmological constant- a mathematical auxiliary quantity introduced by Einstein in order for space-time to acquire a tendency to expand.

Cosmology A science that studies the universe as a whole.

Redshift - shift of lines in the spectrum of a celestial body towards the red end (toward a longer wavelength) as a result of the Doppler effect when the body is removed, as well as under the influence of its gravitational field. Numerically, the redshift is usually characterized by the value , where is the wavelength of the spectral line in radiation coming from a cosmic source, and is the wavelength of the same line, measured in the spectrum of a stationary laboratory source. If radiation is emitted from the surface of a compact massive object, then its gravitational redshift is , where and is the mass and radius of the body, the gravitational constant.

multiple star- a group of three or more stars close to each other.

radial velocity is the projection of the object's velocity vector onto the observer's line of sight; it is considered positive if the object is moving away from the observer, and negative if it is approaching.

magnetars- pulsars with superstrong magnetic fields (up to ) can be sources of gamma-ray bursts.

Magnetosphere- a region of space surrounding a planet or star, in which its magnetic field dominates the magnetic fields of other bodies.

Minor planets- cm. asteroids.

interstellar dust- solid microscopic particles that are part of the interstellar medium and are mainly responsible for the interstellar absorption of light. The particle size of interstellar dust is from 0.01 to 0.2 microns. The dust grains probably have a refractory core (graphite, silicate, or metal) surrounded by organic matter or an ice shell.

interstellar medium– The share of the interstellar medium is less than 1% of the mass in elliptical galaxies, about 5% in spiral galaxies and more than 10% in irregular ones.

Interstellar absorption of light– attenuation of optical radiation propagating through the interstellar medium. Scattering and absorption of light is mainly due to interstellar dust and therefore reaches its maximum value in the direction of dense gas and dust interstellar clouds concentrated in the disk of the Galaxy.

interstellar gas- an extremely rarefied gas that fills the space between stars; main component of the interstellar medium. In terms of elemental composition, it consists of 90% hydrogen and 10% helium with a small admixture of more complex elements.

Meteor- a flash or a luminous trail that remains for a moment after the destruction of a small cosmic body (meteoroid) that has flown into the Earth's atmosphere.

Meteorite(Greek "stone from the sky") - a solid body of natural origin that fell to the surface of the Earth from space. Usually distinguish stone, iron-stone and iron meteorites.

meteoroid (meteoroid)- a solid interplanetary body, which, when entering the planet's atmosphere, causes the phenomenon of a meteor, sometimes culminating in a meteorite falling to the surface of the planet.

Microwave background radiation- cm. relic radiation.

Milky Way- a light ragged foggy band encircling the night sky in a large circle, formed by the light of millions of distant stars in the disk of our Galaxy. In Western literature milky way also called our galaxy itself.

Molecular cloud - an area of ​​increased density of matter in the interstellar medium, which is characterized by almost complete opacity for optical and ultraviolet radiation and, for this reason, has mainly a molecular composition. The main component of such clouds is hydrogen molecules (H 2), but there are also more complex molecules. The density of a substance in a molecular cloud is 100 - 500 molecules per . The temperature inside the cloud is less than 100 K, and in its densest parts it is only 5-10 K.

Neutrino - lightest (possibly massless) elementary particle matter that participates only in weak and gravitational interactions.

Neutron- an uncharged particle, very close in properties to a proton. Neutrons make up more than half of the particles that make up most atomic nuclei.

neutron star - cosmic body of stellar mass, mainly composed of neutrons.

wrong galaxy- a galaxy that has an asymmetric shape and a ragged structure that is not characteristic of typical elliptical or spiral galaxies. In various systems of morphological classification, irregular galaxies are designated as I, Ir or Irr (from the English. irregular wrong). An example of irregular galaxies are the Magellanic Clouds.

New star - a star that increases its brightness thousands (sometimes millions) of times in a few hours, and then dimmers over several weeks and returns to its original brightness. The nova phenomenon is associated with large-aged stars that have practically completed their evolution. It occurs in close binary systems where one of the components is a degenerate star (white dwarf or neutron star). At a certain stage in the evolution of such systems, the matter of the second component, a normal star, can begin to flow onto a neighboring degenerate star. When a critical mass of matter accumulates on the surface of a white dwarf (or on the magnetosphere of a neutron star), a thermonuclear explosion occurs, tearing off the shell from the star and increasing its luminosity thousands of times. Repeated outbreaks of repeated new ones were observed.

General theory of relativity- A theory created by Einstein, which is based on the assumption that the laws of science should be the same for all observers, regardless of how these observers move. In general relativity, the existence of gravitational interaction is explained by the curvature of four-dimensional space-time.

supernova remnant- an expanding gas nebula, which owes its birth to the explosion of a supernova. Young supernova remnants are expanding at a rate of .

Parallax - change in the apparent position of the object (against the background of much more distant objects) when the observer moves.

Greenhouse effect– retention of heat near the surface of the planet, caused by the opacity of the atmosphere for infrared radiation, the main agent of heat transfer of the planet. A particularly strong greenhouse effect of the atmosphere is manifested in Venus, which, as a result, has high temperature surfaces.

Parsec (pc) - the distance to an object whose annual parallax is equal (hence the name "parallax" + "second").

Variable star - star that changes visible shine. An eclipsing variable star is a binary system in which one component periodically obscures the other from an observer on Earth. Physical variable stars such as Cepheids, flare stars, novae and supernovae do change their luminosity as a result of internal processes.

Period – luminosity ratio- the relationship between the absolute stellar magnitude (i.e. luminosity) and the period of brightness change in variable stars - Cepheids.

Period-luminosity ratio- the relationship between the absolute stellar magnitude (i.e. luminosity) and the period of change in its brightness in variable stars - Cepheids.

Planet - a celestial body massive enough for its own gravity to give it a spheroidal shape, but not massive enough for thermonuclear reactions to take place in its depths.

giant planet - a large planet, close in mass to Jupiter or Saturn, having a low average density, consisting mainly of hydrogen and helium.

terrestrial planet- one of the 4 planets closest to the Sun, in terms of size, density and internal structure similar to the earth. This group includes Mercury, Venus, Earth and Mars.

planetary nebula- a bright nebula around an old star, formed by the upper outflowing layers of its atmosphere; usually this is a shell thrown off by a giant star.

Hubble constant - cm. Hubble law.

asteroid belt - cm. asteroids.

Kuiper belt (Edgeworth-Kuiper) - a region of the solar system beyond the orbit of Neptune, inhabited by small objects such as asteroids and comet nuclei.

protostar- a star at the final stage of its formation, up to the moment of initiation of thermonuclear reactions in the core, after which the compression of the protostar stops, and it becomes a main sequence star.

Right Ascension - one of the coordinates in the equatorial system, the angle measured in the direction of the annual movement of the Sun (i.e. to the east) along the celestial equator from the vernal equinox to the meridian passing through the celestial pole and the heavenly body. It is denoted by the letter , measured in garadus, arc minutes and seconds, or in hours, minutes and seconds of the conventional dial (the hour corresponds to the angle).

Pulsar- an astronomical object that emits powerful, strictly periodic pulses of electromagnetic radiation. Radio pulsars were the first to be discovered, and then optical, X-ray and gamma-ray pulsars were discovered, and these turned out to be objects of the same nature - neutron stars. The frequency of pulses for each pulsar is individual and ranges from 640 pulses per second to 1 pulse per 5 seconds. The periods of most pulsars range from 0.5 to 1 s.

Radial speed- cm. beam speed.

Radial belts - the outer layers of the planet's atmosphere, in which, due to its magnetic field, high-energy charged particles (tens of MeV) are retained and accumulated. The Earth's magnetic field captures solar wind particles (protons and electrons) and forms around the Earth two toroidal regions filled with them at altitudes of about 4000 and 17000 km from the Earth's surface.

Radioactivity- spontaneous transformation of one atomic nucleus into another.

radio galaxy A galaxy with unusually strong radio emission. Usually these are large massive galaxies with a dense central region - the core. In the most powerful radio galaxies, the luminosity in the radio range exceeds the optical luminosity.

Resolution (resolution) of an optical device - an indicator that characterizes its ability to give separate images of two close to each other points of the object of observation.

open clusters- star clusters in the disks of spiral and irregular galaxies, usually consisting of several hundred or thousands of stars of young or moderate age (10 - 100 million years).

CMB radiation – electromagnetic radiation, which comes with the same intensity from all regions of the sky and has a spectrum corresponding to thermal radiation at a temperature of 2.73 K. The maximum in the spectrum falls on 1 mm, it is also called microwave background radiation. The relic radiation was born more than 13 billion years ago, when the Universe as a whole was much denser and hotter than in the current era. During the expansion of the Universe, the temperature of the radiation decreased by about a thousand times.

Reflector - a telescope that uses a lens as an objective.

supernova- a star, the brightness of which, during a flash, increases by tens of magnitudes (i.e., millions and even billions of times) during several days, and then gradually decreases over several months or years. Typically, supernovae include flares with an optical power of more than . The reason for the explosion of a star as a supernova is its explosion at the final stage of evolution, which almost completely destroys the star.

Luminosity is the radiation power of the celestial body.

Light year- the distance that light travels in vacuum in 1 Earth year; is , or .

Seyfert galaxies- a type of spiral galaxies with active nuclei. Named after the American astronomer Carl Seifert (1911-1960). A feature of Seyfert galaxies is a bright and very compact (star-like) core with broad emission lines in the spectrum. About 1% of spiral galaxies are Seyfert.

Strong interaction - the strongest and shortest-range of the four fundamental forces. Due to the strong interaction, quarks are held inside protons and neutrons, and protons and neutrons, when brought together, form atomic nuclei.

Singularity- a point in space-time at which its curvature becomes infinite.

Weak interaction - the second weakest of the four known interactions. Has a very short range. All particles of matter take part in the weak interaction, but the particles that carry the interaction do not participate in it.

Synchrotron radiation– nonthermal radiation emitted by relativistic charged particles in a magnetic field. It is due to the acceleration of particles that appears when their trajectory is curved in a magnetic field.

Declension - one of the equatorial coordinates, defined as the angular distance between the celestial equator and the observed object. Denoted by the letter , measured in angular degrees, minutes and seconds.

Cluster- a group of stars or galaxies that constitutes a stable system due to mutual attraction. Among the clusters of stars, spherical and scattered ones are distinguished; among clusters of galaxies - right and wrong.

Constellations - parts of the starry sky, into which it was conditionally divided in ancient times. The modern boundaries dividing the entire celestial sphere into 88 constellations were established by the International Astronomical Union in 1922-1935. These boundaries pass only along the diurnal parallels and declination circles of the equatorial coordinate system of the epoch of 1875.

Spectral types of stars– groups of stars identified by the nature of their spectra. Closely related to the temperature of stellar atmospheres. The sequence of spectral types corresponding to the effective temperature range from 50000 to 2000 K is denoted by the letters O, B, A, F, G, K, M, L. The gap between neighboring classes is divided into 10 subclasses - from 0 to 9. The spectral class of the Sun is G 2.

Special Relativity - Einstein's theory, the starting point of which is that the laws of science must be the same for all freely moving observers, regardless of their speed.

Spin is an internal property of a particle associated with its rotation around its own axis.

Stationary state - state that does not change with time: a ball rotating at a constant speed is in a stationary state, because, despite the rotation, at every moment it looks the same.

supersymmetry– symmetry of the physical system, uniting the states that obey different statistics; dealt with in quantum theory fields.

dark energy- a hypothetical form of energy with unusual properties, which, in the framework of general relativity, lead to the appearance of a general gravitational repulsion ("anti-gravity").

Singularity theorem − a theorem proving that, under certain conditions, a singularity must exist and that, in particular, the beginning of the universe must be a singularity.

Grand Unified Theory - theory that combines electromagnetic, strong and weak interactions.

Nebulae- clouds of interstellar gas and dust, visible due to their own radiation, reflection or absorption of stellar light.

Background of microwave radiation - radiation that arose during the glow of the hot early Universe (called relic). It is now experiencing such a strong redshift that it does not register as light, but as microwaves (radio waves with centimeter wavelengths).

Photon is a quantum of light.

Photosphere - the opaque bottom layer of the Sun that we see in optical telescope and perceive as the surface of the Sun. The thickness of the photosphere is 200 - 300 km, the temperature in it decreases with height from 8-10 thousand K to 4300 K. The photosphere differs from other layers of the Sun by its minimum temperature and low degree of gas ionization.

Fraunhofer lines - dark absorption lines observed against the background of the continuous spectrum of the Sun and stars.

Black hole- an area in space-time that has arisen during a strong compression of matter, in which the gravitational attraction is so strong that neither matter, nor light, nor other information carriers can leave it. A black hole is surrounded by a surface from which nothing can escape - the "event horizon".

globular cluster- a star cluster that differs from an open cluster in a large number of stars, their higher concentration towards the center of the cluster, and a significantly older age, close to the age of the Galaxy. Globular clusters usually contain stars.

exoplanet, extrasolar planet- a planet belonging to a different, non-solar planetary system, revolving around a different star. It is also possible the existence of free planets that are not associated with a particular star.

Electromagnetic interaction - interaction that occurs between particles that have electric charge. The second strongest of the four fundamental forces.

Elementary particle - a particle that is considered indivisible.

Ecliptic - the apparent path of the Sun on the celestial sphere during a tropical year; a great circle in the plane of the earth's orbit.

Epoch- a specific point in time used by astronomers to indicate the values ​​of various variables, which makes their comparison possible (for example, the coordinates of stars, the orientation of planetary orbits, the periods of pulsars, etc.). The standard epoch J 2000 is now widely used in astronomy. It occurs at noon on January 1, 2000 (January 1.5, 2000 = JD 2451545.0).

Julian days (JD)- a system of continuous time counting, proposed in 1583 by Joseph Scaliger for the convenience of astronomical and chronological calculations. Julian days are counted from Greenwich noon on January 1, 4713 BC. on julian calendar. Each day in this account has its own serial number. The Julian day begins at GMT noon. For example, julian date 2454101.625 JD corresponds to the beginning of the day on January 1, 2007.

Julian dates for January 0 of the specified year:

Cellular structure of the Universe - large-scale inhomogeneity of the spatial distribution of galaxies and clusters of galaxies, most of which are concentrated in the "walls of cells", practically empty inside. The characteristic cell size is about 10 Mpc, the wall thickness is 3-4 Mpc. Separate fragments of the cellular structure are sometimes called superclusters of galaxies. Superclusters often have a highly elongated shape, like threads, since they are formed by the intersection of cell walls. The largest and richest clusters of galaxies are located in the nodes formed by the intersection of threads (edges) of cells.

Concise Astronomical Dictionary

Azimuth- angular distance along the mathematical horizon from the point of the south (astronomical) or north (geodesic) to the star's vertical.

Apogee- the point of the orbit of a body circling around it, the most distant from the Earth.

Perihelion argument- the angle in the plane of the orbit of a celestial body, formed by the directions to the ascending node and the perihelion point of the orbit. Counted counterclockwise.

Asteroid (minor planet)- a small planet-like body of irregular shape with an orbit located, as a rule, between the orbits of Mars and Jupiter.

Aphelion- the most distant point from the Sun in the orbit of a body circling around it.

fireball A meteor that is brighter than Venus.

Magnitude- a number characterizing the brilliance of the object. The smaller the magnitude, the greater the brilliance.

Vertical- a large semicircle of the celestial sphere, passing through the zenith, the luminary nadir.

Sunrise- the moment the luminary crosses the horizon, when it passes from the invisible part of the celestial sphere to the visible.

Climbing straight- the angular distance along the celestial equator from the vernal equinox to the hour circle passing through the luminary. It is counted in the direction opposite to the daily rotation of the celestial sphere.

Atomic time- time, the standard of which is 1 second of the atomic cesium clock.

Worldwide - local average solar time Greenwich meridian.

Circle of the celestial sphere large- intersection of the celestial sphere with an arbitrary plane passing through the center of the celestial sphere.

Sentinel - a large semicircle of the celestial sphere, passing through the poles of the world and the luminary.

climax- the moment the luminary crosses the celestial meridian.

Limbo- the visible edge of the star's disk in projection onto the celestial sphere.

sheer line- a straight line coinciding with the direction of the plumb line at a given point on the Earth.

meridian geographic- a large semicircle passing through the poles of the Earth.

Celestial - a large circle of the celestial sphere, the plane of which passes through the plumb line and the axis of the world.

Zero (Greenwich) - the meridian passing through the Greenwich Observatory in England.

The main (central) time zone - geographic meridians, passing approximately in the middle of the time zones and spaced exactly 15 degrees in longitude from each other.

Meteor- a light phenomenon in the Earth's atmosphere when a meteoroid hits and burns in it.

Meteorite- a meteoroid that has fallen on the surface of the Earth or another planet.

meteoroid- a solid body moving in interplanetary space, smaller than an asteroid.

Nadir- located under the feet of the observer, the point of intersection of the plumb line with the surface of the celestial sphere.

Orbital inclination- the dihedral angle formed by the planes of the ecliptic and the orbit of a celestial body.

New moon- the phase of the Moon, at which its ecliptic longitude is equal to the ecliptic longitude of the Sun.

astronomical night- the period of the day between astronomical twilight, when the Sun is submerged under the horizon below 18 degrees.

world axis- a straight line around which the apparent rotation of the celestial sphere occurs.

Parallax annual- the angle at which the radius of the Earth's orbit is visible from a given point. - daily - the angle at which the radius of the Earth is visible from a given point.

Perigee- the closest point to the Earth in the orbit of a body revolving around it.

Perihelion- the closest point to the Sun in the orbit of a body revolving around it.

Planet configuration - mutual arrangements planets and the Sun on the celestial sphere of the earthly observer.

Watch belt- a section of the Earth, for all points of which the same standard time is taken.

Coatings celestial bodies moon- phenomena of the occlusion of celestial bodies by the disk of the Moon as it moves relative to the stars.

Stars by asteroids - the phenomenon of closing a star by an asteroid disk.

Full moon- the phase of the Moon, at which the difference between the ecliptic longitudes of the Sun and the Moon is 180 degrees.

Population index- the average ratio of the number of meteors of a given stream with a magnitude brighter than (m + 1) to the number of meteors of this stream brighter than m.

meteor shower- 1) the phenomenon of multiple meteor falls over several hours or days from one radiant; 2) a swarm of meteoroids moving in one orbit around the Sun.

Confrontation- the configuration of two celestial bodies, in which the difference between their ecliptic longitudes is 180 degrees.

Equinox- the moment of intersection of the center of the solar disk of the celestial equator during the transition to North hemisphere(spring) or southern (autumn).

Equinox points- the points of intersection of the celestial equator and the ecliptic (points of the spring and autumn equinoxes). At the vernal equinox, the Sun crosses the celestial equator from southern hemisphere celestial sphere to the north.

Epoch - the point in time at which the position of the vernal equinox is taken as the origin of the equatorial and ecliptic coordinates.

Radiant- the point of convergence of parallel rays in perspective. It is very clearly defined for meteors belonging to the same stream.

Refraction- the phenomenon of light refraction at the boundary of two media with different optical density. Astronomical refraction increases the apparent height of the stars above. horizon.

Saros- cycle of eclipses, repeating with an interval of 6585 days (18 years and 10 (11) days). Saros contains 41 solar and 29 shadow lunar eclipses.

declination- angular distance along the hourly circle from the celestial equator to the luminary. Positive to the north and negative to the south.

Beam speed- projection of the speed of the celestial body relative to the observer on the line of sight. It is positive when the body moves away from the observer and negative when it approaches.

Compound- the configuration of two celestial bodies, in which their ecliptic longitudes are equal. In the case of the connection of the inner planet with the Sun, a lower connection is distinguished - when the planet is located between the Earth and the Sun, and an upper connection - when the planet is located behind the Sun.

Sun mean equatorial- an imaginary point moving uniformly along the celestial equator so that at each moment its right ascension is equal to the average longitude of the true Sun.

Solstice- the moment when the center of the solar disk passes the northernmost (summer) or southern (winter) point of the ecliptic.

standing- an apparent stop in the apparent movement of the planet during the transition from direct to backward movement and vice versa.

Twilight- part of the day after sunset or before sunrise.

Astronomical - limited to the immersion of the Sun under the horizon up to 18 degrees. At greater immersion astronomical night begins.

Civilian - are limited to the immersion of the Sun under the horizon up to 6 degrees.

Navigational - limited to the immersion of the Sun under the horizon up to 12 degrees.

Starry day- the time interval between two successive climaxes of the same name of the vernal equinox on the same geographic meridian.

True solar - the time interval between two successive culminations of the same name of the center of the visible disk of the Sun on the same geographic meridian.

Mean solar - the time interval between two consecutive culminations of the same name of the mean equatorial Sun on the same geographic meridian.

Sphere celestial- sphere of arbitrary radius centered at the point of observation.

Terminator- the line separating the dark part of the visible disk of the planet from the light.

Optical thickness - natural logarithm the ratio of the intensity of light before entering an absorbing medium to its intensity after it has passed.

Knot- the point of intersection of the orbit of a celestial body with the ecliptic. Distinguish between ascending and descending nodes.

Clock angle- the angular distance along the celestial equator from the top of the equator to the hour circle passing through the luminary. It is counted in the direction of the daily movement of the celestial sphere.

Equation of time is the difference between mean and true solar time.

eclipse phase- the ratio of the closed part of the diameter of the eclipsed body passing through the center of the eclipsing body to the full diameter of the eclipsed body. For total eclipse this value is equal to one plus the ratio of the minimum distance between the edges of the eclipsing and eclipsed body to the diameter of the eclipsed body.

Planet phase- the ratio of the area of ​​the illuminated part of the visible disk to its entire area.

comet tail comet gas and dust tail.

Geographic latitude- the angle between the plane of the earth's equator and the plumb line.

earth's equator- a large circle on the surface of the Earth, the plane of which is perpendicular to the axis of rotation. - celestial - a large circle of the celestial sphere, the plane of which is perpendicular to the axis of the world.

Ecliptic- 1) the plane of the Earth's orbit; 2) the apparent annual path of the Sun relative to the stars in the celestial sphere.

Eccentricity- a value that characterizes the difference between the shape of the orbit and the circular one. For a circle it is equal to zero, for a parabola - to one.

Orbital elements- a set of parameters that uniquely characterizes the orbit of a celestial body.

Elongation- angular distance of the planet (comet, asteroid) from the Sun. There are eastern (planet to the east of the Sun) and western (planet to the west of the Sun) elongation.

Epoch- point in time selected as the initial reference.

Ephemeris- a table that shows the calculated coordinates of a celestial body for various points in time.

Preparation and publication of the project "Astrogalaxy": June 12, 2005.

Below is a list of useful words for astronomy. These terms were created by scientists to explain what happens in outer space.

It is useful to know these words, without understanding their definitions it is impossible to study the Universe and explain yourself on the topics of astronomy. I hope that the basic astronomical terms will remain in your memory.

Absolute value - How bright a star would appear if it were 32.6 light-years from Earth.

Absolute zero - The lowest possible temperature, -273.16 degrees Celsius

Acceleration - Change in speed (speed or direction).

Skyglow - The natural glow of the night sky is due to reactions occurring in the upper layers of the Earth's atmosphere.

Albedo - The albedo of an object indicates how much light it reflects. An ideal reflector, such as a mirror, will have an albedo of 100. The moon has an albedo of 7, the earth has an albedo of 36.

Angstrom - A unit that is used to measure the wavelength of light and other electromagnetic radiation.

Annular - Having the shape of a ring or forming a ring.

Apoaster - When two stars that revolve around each other, how far apart can they be.

Aphelion - During the orbital movement of an object around the Sun, when the most distant position from the Sun occurs

Apogee - The position in an object's orbit around the Earth when it is at its furthest from Earth.

Aerolite is a stone meteorite.

Asteroid - Solid, or a small planet revolving around the Sun.

Astrology - The belief that the position of the stars and planets affects the events of human destinies. This has no scientific justification.

Astronomical unit - Distance from the Earth to the Sun Usually written AC.

Astrophysics - The use of physics and chemistry in the study of astronomy.

Atmosphere - The gaseous space surrounding a planet or other body.

Atom - The smallest particle of any element.

Aurora - Beautiful lights over the polar regions, which are caused by the tension of the particles of the Sun when interacting with the Earth's magnetic field.

Axis - The imaginary line on which the object rotates.

Radiation background - Weak microwave radiation coming from space in all directions. It is believed to be a remnant of the Big Bang.

Barycenter - The center of gravity of the Earth and the Moon.

Double stars - A star hotel that actually consists of two stars revolving around each other.

Black Hole - A region of space around a very small and very massive object in which the gravitational field is so strong that not even light can escape from it.

Bolide - A brilliant meteor that can explode during its descent through the Earth's atmosphere.

Bolometer - A detector sensitive to radiation.

Celestial Sphere - An imaginary sphere surrounding the Earth. The term is used to help astronomers explain where objects are in the sky.

Cepheids are variable stars that scientists use to determine how far away a galaxy is, or how far a cluster of stars is from us.

Charge-Coupled Device (CCD) - A sensitive imaging device that replaces photography in most branches of astronomy.

Chromosphere - Part of the Sun's atmosphere, visible during a total solar eclipse.

Circumpolar Star - A star that never sets, it can be viewed all year round.

Clusters - A group of stars or a group of galaxies that are linked together by the forces of gravity.

Color Index - A measure of a star's color that tells scientists how hot the star's surface is.

Coma - A nebula surrounding the nucleus of a comet.

Comet - Small, frozen masses of dust and gas orbiting the Sun.

Conjunction - A phenomenon in which a planet approaches another planet or star, and moves between the other object and the body of the Earth.

Constellations - Groupings of stars that were given names by ancient astronomers.

Corona - The outer part of the Sun's atmosphere.

Coronagraph - A type of telescope designed to view the Corona Sun.

Cosmic rays - High-speed particles that reach the Earth from outer space.

Cosmology - The study of the universe.

Day - The amount of time it takes for the Earth to rotate around its axis.

Density - The compactness of matter.

Direct motion - Objects moving around the Sun in the same direction as the Earth - move in a direct motion, in contrast to objects moving in the opposite direction - they move in a retrograde motion.

Diurnal motion - The apparent movement of the sky from East to West, caused by the Earth moving from West to East.

Ash light - A faint glow of the Moon over the dark side of the Earth. Light is caused by reflection from the Earth.

Eclipse - When we see an object in the sky blocked by the shadow of another object or the shadow of the Earth.

The ecliptic is the path of the sun, moon and planets that everyone follows in the sky.

Ecosphere - The area around a star where the temperature allows life to exist.

Electron - A negative particle that revolves around an atom.

Element - A substance that cannot be broken down further. There are 92 known elements.

The equinoxes are March 21st and September 22nd. Twice a year, when day and night are equal in time, around the world.

Second escape velocity - The speed required for an object to escape from the grip of another object's gravity.

Exosphere - The outer part of the Earth's atmosphere.

Flares - the effect of solar flares. Beautiful eruptions in the outer part of the Sun's atmosphere.

Galaxy - A group of stars, gas and dust that are held together by gravity.

Gamma - Extremely short-wavelength energetic electromagnetic radiation.

Geocentric - Simply means that the Earth is at the center. People used to believe that the universe is geocentric; The earth for them was the center of the universe.

Geophysics - Exploration of the Earth using physics.

HI region - Cloud of neutral hydrogen.

NI region - A cloud of ionized hydrogen.

Hertzsprung-Russell Diagram - A diagram that helps scientists understand different kinds stars.

Hubble constant - The ratio between the distance from an object and the speed at which it is moving away from us. Further, the object moves the faster, the farther away from us it becomes.

Planets that have an orbit less than the earth's - Mercury and Venus, which lie closer to the Sun than the Earth, are called the lower planets.

Ionosphere - The region of the Earth's atmosphere.

Kelvin - The measurement of temperature is often used in astronomy. 0 degrees Kelvin is equal to -273 degrees Celsius and -459.4 degrees Fahrenheit.

Kepler's Laws - 1. Planets move in elliptical orbits with the Sun at one of the foci. 2. An imaginary line connecting the center of the planet with the center of the Sun. 3. The time required for the planet to orbit around the Sun.

Kirkwood gaps - Regions in the asteroid belt where there are almost no asteroids. This is due to the fact that the giant Jupiter changes the orbits of any object that enters these areas.

A light year is the distance a ray of light travels in one year. This is approximately 6,000,000,000,000 (6000000000000) miles.

Finiteness - The edge of any object in outer space. The Moon zone, for example.

Local Group - A group of two dozen galaxies. This is the group to which our Galaxy belongs.

Lunation - The period between new moons. 29 days 12 hours 44 minutes.

Magnetosphere - The region around the object where the influence magnetic field object can be felt.

Mass - Not the same as weight, although the mass of an object helps determine how much it will weigh.

Meteor - A shooting star, these are dust particles entering the Earth's atmosphere.

Meteorite - An object from outer space, such as a rock, that falls to the Earth and lands on its surface.

Meteoroids - Any small object in outer space, such as clouds of dust or rocks.

Micrometeorites - An extremely small object. They are so small that when they enter the Earth's atmosphere, they do not create the effect of a star.

Milky Way - Our Galaxy. (The word "Galaxy" actually means the Milky Way in Greek.)

Minor planet - Asteroid

Molecule - A group of atoms connected to each other.

Multiple Stars - A group of stars that orbit each other.

Nadir - This is a point on the celestial sphere, directly below the observer.

Nebula - A cloud of gas and dust.

Neutrino - A very small particle that has no mass or charge.

Neutron Star - The remains of a dead star. They are incredibly compact and spin very fast, some spinning 100 times per second.

Novelty - A star that suddenly flashes before disappearing again - a flash many times stronger than its original brightness.

Terrestrial spheroid - A planet that is not perfectly round because it is wider in the middle, and shorter from top to bottom.

Eclipse - An occultation of one celestial body by another.

Opposition - When the planet is exactly opposite the Sun, so that the Earth is between them.

Orbit - The path of one object around another.

Ozone - An area in the Earth's upper atmosphere that absorbs many of the deadly radiations coming from space.

Parallax - The shift of an object when viewed from two different locations. For example, if you close one eye and look at your thumbnail and then switch eyes, you will see everything in the background shifting back and forth. Scientists use this to measure the distance to stars.

Parsec - 3.26 light years

Penumbra - The light part of the shadow is at the edge of the shadow.

Periastra - When two stars that revolve around each other are at their closest point.

Perigee - The point in an object's orbit around the Earth when it is closest to the Earth.

Perihelion - When an object that revolves around the sun is at its closest point to the sun

Disturbances - Disturbances in the orbit of a celestial object caused by gravitational attraction another object.

Phases - Obviously changing shape of the Moon, Mercury and Venus due to how much of the sun side is facing the Earth.

Photosphere - The bright surface of the Sun

Planet - An object that moves around a star.

Planetary nebula - A nebula of gas surrounding a star.

Precession - The Earth behaves like a top. Her poles are spinning in circles causing the poles to point in different directions over time. It takes 25,800 years for the Earth to complete one precession.

Proper motion - The motion of stars across the sky as seen from Earth. Closer stars have a higher proper motion than more distant ones, as in your car closer objects such as road signs seem to move faster than distant mountains and trees.

Proton - At the center of an atom, it is made up of one or more protons. It has a positive charge.

Quasar - A very distant, very bright object.

Shining - Square in the sky, where in time meteor shower meteors appear to emanate from.

Radio galaxies - Galaxies that are extremely powerful emitters of radio emission.

Redshift - As an object moves away from the Earth, the light from that object is stretched, making it appear redder.

Revolve - When something moves in a circle around another object, such as the way the Moon circles the Earth, it is said to revolve around that object.

Rotate - When an object rotates it is said to rotate.

Saros cycle - Period of 18 years 11.3 days in which dwarfs repeat.

Satellite - A small object in orbit around a larger one. There are many electronic objects that revolve around the Earth.

Twinkle - The twinkling of stars. Thanks to the Earth's atmosphere.

View - The state of the Earth's atmosphere at a particular point in time. If the sky is clear astronomers say it's good looking.

Selenography is the study of the surface of the moon.

Seyfert galaxies are galaxies with small bright centers. Many Seyfert galaxies are good sources of radio waves.

Shooting Star - Light into the atmosphere as a result of a meteorite falling to Earth.

Sidereal period - The period of time it takes an object in space to complete one complete rotation with respect to the stars.

Solar System — System of planets and other objects orbiting the star Sol, which happens to be our Sun

Solar Wind - A steady stream of particles streaming from the Sun in all directions.

Solstice - June 22 and December 22. The time of year when the day is either short, or long depending on where you are.

Spicules - Planes up to 16,000 kilometers in diameter in the Sun's atmosphere.

Stratosphere - The level of the Earth's atmosphere from about 11-64 km (7-11 miles) above sea level.

Star - A self-luminous object that shines through the release of generated energy in nuclear reactions based on it.

Supernova - A super bright explosion of a star. A supernova can produce the same amount of energy per second as an entire galaxy.

Sundial - An ancient instrument used to tell time.

Sunspots - Dark spots on the surface of the Sun.

Outer Planets - Planets that lie farther from the Sun than the Earth.

Synchronous satellite - artificial satellite, which moves around the Earth at the same speed as it rotates on the Earth, so that it is always higher than the same part of the Earth.

Synodic Period - The time it takes for an object in space to reappear at the same point in relation to two other objects, such as the Earth and the Sun

Syzygy - The position of the Moon in its orbit when in a new or full phase.

Terminator - The line between day and night on any celestial object.

Thermocouple - An instrument used to measure very small amounts of heat.

Slowing down time - The idea that you are approaching the speed of light time slows down and mass increases.

Trojan Asteroids - Asteroids orbiting the Sun following the orbit of Jupiter.