Astronomy
English dictionary

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aberrance; aberrancy; aberration; deviance
a state or condition markedly different from the norm

aberration; distortion; optical aberration
an optical phenomenon resulting from the failure of a lens or mirror to produce a good image

absolute magnitude
(astronomy) the magnitude that a star would have if it were viewed from a distance of 10 parsecs (32.62 light years) from the earth

acceleration; quickening; speedup
the act of accelerating; increasing the speed

albedo; reflective power
the ratio of reflected to incident light

analogue; analog; parallel
something having the property of being analogous to something else

anomaly
(astronomy) position of a planet as defined by its angular distance from its perihelion (as observed from the sun)

anomaly; anomalousness
deviation from the normal or common order or form or rule

aphelion
apoapsis in solar orbit; the point in the orbit of a planet or comet that is at the greatest distance from the sun

apogee
apoapsis in Earth orbit; the point in its orbit where a satellite is at the greatest distance from the Earth

apogee; culmination
a final climactic stage; "their achievements stand as a culmination of centuries of development"

apparition
the appearance of a ghostlike figure; "I was recalled to the present by the apparition of a frightening specter"

aspect
a characteristic to be considered

asteroid
any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)

astrolabe
an early form of sextant

astronaut; spaceman; cosmonaut
a person trained to travel in a spacecraft; "the Russians called their astronauts cosmonauts"

astronomer; uranologist; stargazer
a physicist who studies astronomy

astronomy; uranology
the branch of physics that studies celestial bodies and the universe as a whole

atmosphere; air
the mass of air surrounding the Earth; "there was great heat as the comet entered the atmosphere"; "it was exposed to the air"

aura; aureole; halo; nimbus; glory; gloriole
an indication of radiant light drawn around the head of a saint

aureole; corona
the outermost region of the sun's atmosphere; visible as a white halo during a solar eclipse

axis; axis of rotation
the center around which something rotates

azimuth; AZ
the azimuth of a celestial body is the angle between the vertical plane containing it and the plane of the meridian

belt
an elongated region where a specific condition or characteristic is found; "a belt of high pressure"

binary star; binary; double star
a system of two stars that revolve around each other under their mutual gravitation

black hole
a region of space resulting from the collapse of a star; extremely high gravitational field

canal
(astronomy) an indistinct surface feature of Mars once thought to be a system of channels; they are now believed to be an optical illusion

celestial; heavenly
relating to or inhabiting a divine heaven; "celestial beings"; "heavenly hosts"

celestial equator; equinoctial circle; equinoctial line; equinoctial
the great circle on the celestial sphere midway between the celestial poles

celestial sphere; sphere; empyrean; firmament; heavens; vault of heaven; welkin
the apparent surface of the imaginary sphere on which celestial bodies appear to be projected

centrifugal force
the outward force on a body moving in a curved path around another body

climate; clime
the weather in some location averaged over some long period of time; "the dank climate of southern Wales"; "plants from a cold clime travel best in winter"

cold
having a low or inadequate temperature or feeling a sensation of coldness or having been made cold by e.g. ice or refrigeration; "a cold climate"; "a cold room"; "dinner has gotten cold"; "cold fingers"; "if you are cold, turn up the heat"; "a cold beer"

cold; coldness; low temperature; frigidity; frigidness
the absence of heat; "the coldness made our breath visible"; "come in out of the cold"; "cold is a vasoconstrictor"

collision; hit
(physics) a brief event in which two or more bodies come together; "the collision of the particles resulted in an exchange of energy and a change of direction"

coma
(astronomy) the luminous cloud of particles surrounding the frozen nucleus of a comet; forms as the comet approaches the sun and is warmed

coma; comatoseness
a state of deep and often prolonged unconsciousness; usually the result of disease or injury

comet
(astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit

conjunction; alignment
(astronomy) apparent meeting or passing of two or more celestial bodies in the same degree of the zodiac

constellation
a configuration of stars as seen from the earth

corona discharge; corona; corposant; St. Elmo|s fire; Saint Elmo|s fire; Saint Elmo|s light; Saint Ulmo|s fire; Saint Ulmo|s light; electric glow
an electrical discharge accompanied by ionization of surrounding atmosphere

cosmic
of or from or pertaining to or characteristic of the cosmos or universe; "cosmic laws"; "cosmic catastrophe"; "cosmic rays"

cosmology
the metaphysical study of the origin and nature of the universe

cosmology; cosmogony; cosmogeny
the branch of astrophysics that studies the origin and evolution and structure of the universe

Crab Nebula
a remnant of a supernova detected first in 1054 AD

crater
a bowl-shaped depression formed by the impact of a meteorite or bomb

crew
the men and women who man a vehicle (ship, aircraft, etc.)

declination; celestial latitude; dec
(astronomy) the angular distance of a celestial body north or to the south of the celestial equator; expressed in degrees; used with right ascension to specify positions on the celestial sphere

degree; arcdegree
a measure for arcs and angles; "there are 360 degrees in a circle"

density; denseness
the amount per unit size

departure; going; going away; leaving
the act of departing

discovery; find; uncovering
the act of discovering something

distance
the property created by the space between two objects or points

distant
separated in space or coming from or going to a distance; "distant villages"; "the sound of distant traffic"; "a distant sound"; "a distant telephone call"

distant; remote
located far away spatially; "distant lands"; "remote stars"

Earth; earth; world; globe
the 3rd planet from the sun; the planet we live on; "the Earth moves around the sun"; "he sailed around the world"

eclipse; occultation
one celestial body obscures another

ecliptic
the great circle representing the apparent annual path of the sun; the plane of the Earth's orbit around the sun; makes an angle of about 23 degrees with the equator; "all of the planets rotate the sun in approximately the same ecliptic"

egress; emersion
(astronomy) the reappearance of a celestial body after an eclipse

ellipse; oval
a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it; "the sums of the distances from the foci to any point on an ellipse is constant"

entrance; entering; entry; ingress; incoming
the act of entering; "she made a grand entrance"

epoch; date of reference
(astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded

equator
an imaginary line around the Earth forming the great circle that is equidistant from the north and south poles; "the equator is the boundary between the northern and southern hemispheres"

equinoctial point; equinox
(astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic

equinox
either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length

exobiology; space biology; astrobiology
the branch of biology concerned with the effects of outer space on living organisms and the search for extraterrestrial life

explode; burst
burst outward, usually with noise; "The champagne bottle exploded"

exploration
a careful systematic search

explosion; burst
the act of exploding or bursting; "the explosion of the firecrackers awoke the children"; "the burst of an atom bomb creates enormous radiation aloft"

explosion; detonation; blowup
a violent release of energy caused by a chemical or nuclear reaction

finder; discoverer; spotter
someone who is the first to observe something

finder; viewfinder; view finder
optical device that helps a user to find the target of interest

flight; flying
an instance of traveling by air; "flying was still an exciting adventure for him"

fossil fuel
fuel consisting of the remains of organisms preserved in rocks in the earth's crust with high carbon and hydrogen content

full moon; full-of-the-moon; full phase of the moon; full
the time when the Moon is fully illuminated; "the moon is at the full"

galactic
of or relating to a galaxy (especially our galaxy the Milky Way); "the galactic plane"

galaxy; extragalactic nebula
(astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust; "`extragalactic nebula' is a former name for `galaxy'"

gaseous
existing as or having characteristics of a gas; "steam is water is the gaseous state"

Gemini
a zodiacal constellation in the northern hemisphere between Taurus and Cancer on the ecliptic

gravity; gravitation; gravitational attraction; gravitational force
(physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; "the more remote the body the less the gravity"; "the gravitation between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them"; "gravitation cannot be held responsible for people falling in love"--Albert Einstein

heat; hotness; high temperature
the presence of heat

hemisphere
half of a sphere

horizon; apparent horizon; visible horizon; sensible horizon; skyline
the line at which the sky and Earth appear to meet

inclination; inclination of an orbit
(astronomy) the angle between the plane of the orbit and the plane of the ecliptic stated in degrees

ionosphere
the outer region of the Earth's atmosphere; contains a high concentration of free electrons

journey; journeying
the act of traveling from one place to another

Jupiter
the largest planet and the 5th from the sun; has many satellites and is one of the brightest objects in the night sky

latitude; line of latitude; parallel of latitude; parallel
an imaginary line around the Earth parallel to the equator

launch
launch for the first time; launch on a maiden voyage; "launch a ship"

libration
(astronomy) a real or apparent slow oscillation of a moon or satellite; "the libration of the moon"

light year; light-year
the distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers

lightness; weightlessness
the property of being comparatively small in weight; "the lightness of balsa wood"

luminosity; brightness; brightness level; luminance; luminousness; light
the quality of being luminous; emitting or reflecting light; "its luminosity is measured relative to that of our sun"

magnetic declination; magnetic variation; variation
the angle (at a particular location) between magnetic north and true north

magnification
the act of expanding something in apparent size

map
a diagrammatic representation of the earth's surface (or part of it)

Mars; Red Planet
a small reddish planet that is the 4th from the sun and is periodically visible to the naked eye; minerals rich in iron cover its surface and are responsible for its characteristic color; "Mars has two satellites"

Mercury
the smallest planet and the nearest to the sun

meridian; line of longitude
an imaginary great circle on the surface of the earth passing through the north and south poles at right angles to the equator; "all points on the same meridian have the same longitude"

meteorite
stony or metallic object that is the remains of a meteoroid that has reached the earth's surface

meteoroid; meteor
(astronomy) any of the small solid extraterrestrial bodies that hits the earth's atmosphere

methane
a colorless odorless gas used as a fuel

navigation; pilotage; piloting
the guidance of ships or airplanes from place to place

nebula
an immense cloud of gas (mainly hydrogen) and dust in interstellar space

Neptune
a giant planet with a ring of ice particles; the 8th planet from the sun is the most remote of the gas giants; "the existence of Neptune was predicted from perturbations in the orbit of Uranus and it was then identified in 1846"

node
(astronomy) a point where an orbit crosses a plane

nova
a star that ejects some of its material in the form of a cloud and become more luminous in the process

nucleosynthesis
(astronomy) the cosmic synthesis of atoms more complex than the hydrogen atom

nucleus
(astronomy) the center of the head of a comet; consists of small solid particles of ice and frozen gas that vaporizes on approaching the sun to form the coma and tail

nutation
uncontrolled nodding

Oort cloud
(astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto; perturbations (as by other stars) can upset a comet's orbit and may send it tumbling toward the sun

orb; orbit; revolve
move in an orbit; "The moon orbits around the Earth"; "The planets are orbiting the sun"; "electrons orbit the nucleus"

orbit; celestial orbit
the (usually elliptical) path described by one celestial body in its revolution about another; "he plotted the orbit of the moon"

order of magnitude; magnitude
a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10

outer space; space
any location outside the Earth's atmosphere; "the astronauts walked in outer space without a tether"; "the first major milestone in space exploration was in 1957, when the USSR's Sputnik 1 orbited the Earth"

ozone
a colorless gas (O3) soluble in alkalis and cold water; a strong oxidizing agent; can be produced by electric discharge in oxygen or by the action of ultraviolet radiation on oxygen in the stratosphere (where it acts as a screen for ultraviolet radiation)

ozone layer; ozonosphere
a layer in the stratosphere (at approximately 20 miles) that contains a concentration of ozone sufficient to block most ultraviolet radiation from the sun

parallax
the apparent displacement of an object as seen from two different points that are not on a line with the object

penumbra
a fringe region of partial shadow around an umbra

perigee
periapsis in Earth orbit; the point in its orbit where a satellite is nearest to the Earth

perihelion
periapsis in solar orbit; the point in the orbit of a planet or comet where it is nearest to the sun

phase
(astronomy) the particular appearance of a body's state of illumination (especially one of the recurring shapes of the part of Earth's moon that is illuminated by the sun); "the full phase of the moon"

planet
any celestial body (other than comets or satellites) that revolves around a star

planetarium
a building housing an instrument for projecting the positions of the planets onto a domed ceiling

planetary; terrestrial
of or relating to or characteristic of the planet Earth or its inhabitants; "planetary rumblings and eructations"- L.C.Eiseley ; "the planetary tilt"; "this terrestrial ball"

Pluto
a small planet and the farthest known planet from the sun; it has the most elliptical orbit of all the planets; "Pluto was discovered by Clyde Tombaugh in 1930"

Polaris; North Star; pole star; polar star; polestar
the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward it

pole; celestial pole
one of two points of intersection of the Earth's axis and the celestial sphere

pole; magnetic pole
one of the two ends of a magnet where the magnetism seems to be concentrated

probe
a flexible slender surgical instrument with a blunt end that is used to explore wounds or body cavities

propellant; propellent
any substance that propels

propulsion; actuation
the act of propelling

proton
a stable particle with positive charge equal to the negative charge of an electron

pulsar
a degenerate neutron star; small and extremely dense; rotates very fast and emits regular pulses of polarized radiation

quadrate
having four sides and four angles

quasar; quasi-stellar radio source
a starlike object that may send out radio waves and other forms of energy; many have large red shifts

radiation
the act of spreading outward from a central source

radiotherapy; radiation therapy; radiation; actinotherapy; irradiation
(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance

red shift; redshift
(astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding

resistance; opposition
the action of opposing something that you disapprove or disagree with; "he encountered a general feeling of resistance from many citizens"; "despite opposition from the newspapers he went ahead"

right ascension; RA; celestial longitude
(astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere; "one hour of right ascension equals fifteen degrees"

rocket; projectile
any vehicle self-propelled by a rocket engine

rocket; rocket engine
a jet engine containing its own propellant and driven by reaction propulsion

rotation; rotary motion
the act of rotating as if on an axis; "the rotation of the dancer kept time with the music"

satellite; artificial satellite; orbiter
man-made equipment that orbits around the earth or the moon

Saturn
a giant planet that is surrounded by three planar concentric rings of ice particles; the 6th planet from the sun

scientific
of or relating to the practice of science; "scientific journals"

scientist
a person with advanced knowledge of one or more sciences

send; transport; ship
transport commercially

sextant
a measuring instrument for measuring the angular distance between celestial objects; resembles an octant

shuttle
bobbin that passes the weft thread between the warp threads

sky
the atmosphere and outer space as viewed from the earth

solar
relating to or derived from the sun or utilizing the energies of the sun; "solar eclipse"; "solar energy"

solar eclipse
the moon interrupts light from the sun

solar energy; solar power
energy from the sun that is converted into thermal or electrical energy; "the amount of energy falling on the earth is given by the solar constant, but very little use has been made of solar energy"

solar system
the sun with the celestial bodies that revolve around it in its gravitational field

solar wind
a stream of protons moving radially from the sun

solar year; tropical year; astronomical year; equinoctial year
the time for the earth to make one revolution around the sun, measured between two vernal equinoxes

solstice
either of the two times of the year when the sun is at its greatest distance from the celestial equator

south
situated in or facing or moving toward or coming from the south; "the south entrance"

space; infinite
the unlimited expanse in which everything is located; "they tested his ability to locate objects in space"; "the boundless regions of the infinite"

space shuttle
a reusable spacecraft with wings for a controlled descent through the Earth's atmosphere

spectroscopy; spectrometry; spectroscopic analysis; spectrum analysis; spectrographic analysis
the use of spectroscopes to analyze spectra

speed; velocity
distance travelled per unit time

sphere
a three-dimensional closed surface such that every point on the surface is equidistant from the center

spherical
of or relating to spheres or resembling a sphere; "spherical geometry"

spheroid; ellipsoid of revolution
a shape that is generated by rotating an ellipse around one of its axes; "it looked like a sphere but on closer examination I saw it was really a spheroid"

standard atmosphere; atmosphere; atm; standard pressure
a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade

star
(astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior

stellar; astral
being or relating to or resembling or emanating from stars; "an astral body"; "stellar light"

stratosphere
the atmospheric layer between the troposphere and the mesosphere

sunspot; macula
a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field

supernova
a star that explodes and becomes extremely luminous in the process

Taurus
a zodiacal constellation in the northern hemisphere near Orion; between Aries and Gemini

telescope; scope
a magnifier of images of distant objects

temperature
the degree of hotness or coldness of a body or environment (corresponding to its molecular activity)

tendency; inclination
a characteristic likelihood of or natural disposition toward a certain condition or character or effect; "the alkaline inclination of the local waters"; "fabric with a tendency to shrink"

tide
the periodic rise and fall of the sea level under the gravitational pull of the moon

trajectory; flight
the path followed by an object moving through space

transport
move something or somebody around; usually over long distances

universe; existence; creation; world; cosmos; macrocosm
everything that exists anywhere; "they study the evolution of the universe"; "the biggest tree in existence"

Uranus
a giant planet with a ring of ice particles; the 7th planet from the sun has a blue-green color and many satellites; "Uranus was discovered by William Herschel in 1781"

vehicle
a conveyance that transports people or objects

Venus
the second nearest planet to the sun; it is peculiar in that its rotation is slow and retrograde (in the opposite sense of the Earth and all other planets except Uranus); it is visible from Earth as an early `morning star' or an `evening star'; "before it was known that they were the same object the evening star was called Venus and the morning star was called Lucifer"

Virgo
a large zodiacal constellation on the equator; between Leo and Libra

wavelength
the distance (measured in the direction of propagation) between two points in the same phase in consecutive cycles of a wave

weather; weather condition; conditions; atmospheric condition
the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation; "they were hoping for good weather"; "every day we have weather conditions and yesterday was no exception"; "the conditions were too rainy for playing in the snow"

weight
the vertical force exerted by a mass as a result of gravity

weight unit; weight
a unit used to measure weight; "he placed two weights in the scale pan"

white dwarf; white dwarf star
a faint star of enormous density

zenith
the point above the observer that is directly opposite the nadir on the imaginary sphere against which celestial bodies appear to be projected

zodiac
(astrology) a circular diagram representing the 12 zodiacal constellations and showing their signs

zone
a locally circumscribed place characterized by some distinctive features