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59 Cards in this Set
- Front
- Back
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Autumnal Equinox
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The Autumnal Equinox signals the end of the summer months and the beginning of winter. At this time of year, days have been shortening since the Summer Solstice some three months earlier, and the Equinox is the point where nights reach the same length as days. After this point, the Sun will shine lower and lower on the horizon until the Winter Solstice in about three months' time. in about three months' time.
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Celestial Equator
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The celestial equator is a great circle on the imaginary celestial sphere, in the same plane as the Earth's equator
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Celestial Pole
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The north and south celestial poles are the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the imaginary rotating sphere of stars called the celestial sphere.
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Celestial Sphere
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In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis.
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Circumpolar Star
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A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets (that is, never disappears below the horizon), due to its proximity to one of the celestial poles
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Declination
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In astronomy, declination (abbrev. dec or δ) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle.
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Diurnal Motion
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an astronomical term referring to the apparent daily motion of stars around the Earth, or more precisely around the two celestial poles. It is caused by the Earth's rotation on its axis, so every star apparently moves on a circle, that is called the diurnal circle.
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Ecliptic
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The ecliptic is the apparent path that the Sun traces out in the sky during the year, appearing to move eastwards on an imaginary spherical surface, the celestial sphere, relative to the (almost) fixed stars.
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Equinox
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An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the centre of the Sun being in the same plane as the Earth's equator.
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Gravitation
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Gravitation, or gravity, is one of the four fundamental interactions of nature, along with strong interaction, electromagnetic force and weak interaction. It is the means by which objects with mass attract one another
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Lunar Eclipse
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A lunar eclipse occurs when the moon passes behind the earth such that the earth blocks the sun’s rays from striking the moon. This can occur only when the Sun, Earth and Moon are aligned exactly, or very closely so, with the Earth in the middle.
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Partial Eclipse
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An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another. When an eclipse occurs within a stellar system, such as the Solar System, it forms the alignment of three or more celestial bodies in the same gravitational system along a straight line.
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Precession
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Precession is a change in the orientation of the rotation axis of a rotating body.
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Right Ascension
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the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.
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Sidereal Month
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The period of the Moon's orbit as defined with respect to the celestial sphere (of the fixed stars, nowadays the International Celestial Reference Frame (ICRF)) is known as a sidereal month because it is the time it takes the Moon to return to a given position among the stars (Latin: sidus): 27.321661 days (27 d 7 h 43 min 11.5 s).
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Solar Day
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Solar time is time kept or measured by the sun; and its basic division, the day, has been recognized and used since the dawn of history.
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Solar Eclipse
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As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially covers the Sun as viewed from some location on Earth.
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Summer Solstice
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The Summer Solstice occurs exactly when the Earth's axial tilt is closest to the sun at its maximum of 23° 26'.
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Synodic Month
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This is the average period of the Moon's revolution with respect to the sun.
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Terminator
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the line between the day and night sides of a planetary body
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Total Eclipse
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A total eclipse will occur when the observer is located within the umbra of the occulting object.
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Vernal Equinox
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he vernal equinox is the first point (i.e. the start) of the sign of Aries. In this system, it is of no significance that the fixed stars and equinox shift compared to each other due to the precession of the equinoxes.
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Winter Solstice
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The Winter Solstice occurs exactly when the Earth's axial tilt is farthest away from the sun at its maximum of 23° 26'.
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Aphelion
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An apsis, plural apsides is the point of greatest or least distance of a body from the center of its elliptical or eccentric orbit.
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Astronomical unit
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n astronomical unit (abbreviated as AU, au, a.u., or sometimes ua) is a unit of length equal to about 149,597,871 kilometers(92,955,807 miles). It is defined by the International Astronomical Union, and is defined as the mean distance between the Earth and the Sun over one Earth orbit.
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Conjunction
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Conjunction is a term used in positional astronomy and astrology. It means that, as seen from some place (usually the Earth), two celestial bodies appear near one another in the sky. The event is also sometimes known as an appulse.
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Cosmology
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Cosmology in strict usage, refers to the study of the Universe in its totality as it now is (or at least as it can be observed now), and by extension, humanity's place in it.
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Galilean Moons
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The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei in January 1610.
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Kepler’s Laws
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Kepler's laws give an approximate description of the motion of planets around the Sun.
1. The orbit of every planet is an ellipse with the Sun at a focus. 2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time. 3.The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit. |
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Light-year
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light-year, also light year or lightyear, (symbol: ly) is a unit of length, equal to just under 10 trillion kilometres (i.e. 1016 metres or 10 petametres). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year
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Occam’s Razor
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the meta-theoretical principle that "entities must not be multiplied beyond necessity" (entia non sunt multiplicanda praeter necessitatem) and the conclusion thereof, that the simplest solution is usually the correct one.
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Opposition
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Opposition is a term used in positional astronomy to indicate when one celestial body is on the opposite side of the sky when viewed from a particular place (usually the Earth). In particular, two planets are in opposition to each other when their ecliptic longitudes differ by 180°.
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Parallax
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Parallax is an apparent displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.
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Perihelion
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Derivative terms are used to identify the body being orbited. The most common are perigee and apogee, referring to orbits around the Earth (Greek γῆ, gê, "earth"), and perihelion and aphelion, referring to orbits around the Sun (Greek ἥλιος, hēlios, "sun"). During the Apollo program, the terms pericynthion and apocynthion were used when referring to the moon
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Superior Conjunction
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As seen from a planet that is superior, if an inferior planet is on the opposite side of the Sun, it is in superior conjunction with the Sun.
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Synodic Period
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The synodic period is the temporal interval that it takes for an object to reappear at the same point in relation to two other objects (linear nodes), i.e. the Moon relative to the Sun as observed from Earth returns to the same illumination phase
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Blueshift
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Blue shift is the shortening of a transmitted signal's wavelength, and/or an increase in its frequency, due to the relativistic Doppler effect, which indicates that the object is moving toward the observer
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Doppler Shift
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The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the change in frequency of a wave for an observer moving relative to the source of the wave.
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Gamma Ray
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Gamma radiation, also known as gamma rays (denoted as γ), is electromagnetic radiation of high frequency (very short wavelength).
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Photon
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In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation.
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Reflecting Telescope
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A reflecting telescope (also called a reflector) is an optical telescope which uses a single or combination of curved mirrors that reflect light and form an image.
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Refracting Telescope
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A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope).
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Accretion
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The first and most common is the growth of a massive object by gravitationally attracting more matter, typically gaseous matter in an accretion disc.
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Planetesimal
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Planetesimals are solid objects thought to exist in protoplanetary disks and in debris disks.
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Protoplanet
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Protoplanets are moon-sized or larger planetary embryos within protoplanetary discs that have undergone internal melting to produce differentiated interiors.
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Protoplanetary Disks
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A protoplanetary disk (or proplyd) is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star or Herbig star.
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Proplyds
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A protoplanetary disk (or proplyd) is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star or Herbig star.
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Protosun
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A protostar is a large mass that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium.
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Solar Nebula
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According to the nebular hypothesis, the outer two planets are in the "wrong place". Uranus and Neptune (known as the "ice giants") exist in a region where the reduced density of the solar nebula and longer orbital times render their formation highly implausible.
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Dynamo Theory
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The dynamo theory proposes a mechanism by which a celestial body such as the Earth or a star generates a magnetic field.
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Van Allen Radiation Belts
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The Van Allen radiation belt is a torus of energetic charged particles (plasma) around Earth, which is held in place by Earth's magnetic field.
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Retrograde Motion
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Retrograde motion is in the direction opposite to the movement of something else, and is the contrary of direct or prograde motion.
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Chromosphere
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The chromosphere (literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep.
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Core
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The core of the Sun is considered to extend from the center to about 0.2 to 0.25 solar radius.[1] It is the hottest part of the Solar System.
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Coronal Mass Ejection
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A coronal mass ejection (CME) is an ejection of material from the solar corona, usually observed with a white-light coronagraph.
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Neutrino
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are elementary particles that often travel close to the speed of light, are electrically neutral, and are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect.
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Photosphere
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The photosphere of an astronomical object is the region from which externally received light originates
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Prominence
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prominence, also known as autonomous height, relative height, shoulder drop (in North America), or prime factor (in Europe), is a concept used in the categorization of hills and mountains, also known as peaks
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Radiative Zone
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Between the radiative zone and the convection zone is a transition layer called the tachocline. This is a region where the sharp regime change between the uniform rotation of the radiative zone and the differential rotation of the convection zone results in a large shear—a condition where successive horizontal layers slide past one another
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