Astro Geol Flashcards
A type of halo that forms when light passing through an ice crystal bends 22 degrees.
22-degree Halo
A type of halo that forms when light passing through an ice crystal bends 46 degrees.
46-degree Halo
A rotating disk of gas orbiting a star, formed by materials falling toward the star.
Accretion disk
Thermal energy resulting from bolide impacts upon the surface of an object.
Accretionary heating
A rare, stony meteorite that lacks chondrules and resembles terrestrial rocks.
Achondrites
Refers to the brightness of an object in space, measured on a scale from 0 to 1, where 0 is completely dark.
Albedo
The angle an object makes with the horizon, also known as elevation.
Altitude
A type of Solar Eclipse where the New Moon covers the Sun’s center, leaving the outer edges visible as a “ring of fire.”
Annular Solar Eclipse
The latitude 64°34′ S, with all of the area below being part of the Antarctic Circle.
Antarctic Circle
The opposite of the Prime Meridian, located at 180° longitude.
Antimeridian
Two points on the surface of a celestial body that are diametrically opposed to each other.
Antipodes
The lighter part of a shadow that forms when the umbra tapers to a point, involved in annular solar eclipses and planet transits.
Antumbra
The point on Earth’s elliptical orbit farthest away from the Sun.
Aphelion
A landform on Venus that straddles its equator for over 10,000 km, made up of four smaller highlands.
Aphrodite Terra
A spring tide that occurs during a Micromoon, with smaller variation between high and low tides.
Apogean spring tide
Asteroids that cross the Earth’s orbit.
Apollo asteroids
The latitude 64°34′ N, with all of the area above being part of the Arctic Circle.
Arctic Circle
A pattern of stars recognizable from Earth, such as The Big Dipper, which is part of Ursa Major.
Asterism
A rocky object orbiting the Sun, with sizes ranging from a few meters to hundreds of kilometers.
Asteroid
The orbital zone between Mars and Jupiter where most of the Solar System’s asteroids are located.
Asteroid belt
A method to measure the four seasons of a year using the dates of equinoxes and solstices.
Astronomical Season
The darkest of the three twilight phases, occurring during the earliest dawn and latest dusk.
Astronomical Twilight
The time it takes Earth to complete a full orbit around the Sun, also known as Tropical or Solar Year.
Astronomical Year
The layer of gases that surrounds a planet, retained by its gravity.
Atmosphere
A natural electric phenomenon creating bright and colorful light due to charged particles interacting with Earth’s magnetosphere.
Aurora
Also known as Southern Lights, auroras that occur in the Antarctic Circle.
Aurora Australis
Also known as Northern Lights, auroras that occur in the Arctic Circle.
Aurora Borealis
An equinox that occurs during September in the Northern Hemisphere, marking the start of Autumn.
Autumnal Equinox
The angle of tilt of an object from its orbital plane, also known as Obliquity.
Axial Tilt
The imaginary line that an object, usually a planet, rotates around.
Axis
An object’s cardinal direction, specified as the horizontal angle it makes with a reference direction, such as true north.
Azimuth
An upland dome on Venus.
Beta Regio
The areas of a planet that encompass all of its living things.
Biosphere
A celestial object with a gravitational pull so strong that not even light can escape it, formed when a star with more than 20 solar masses collapses.
Black Hole
A Seasonal or Monthly event that occurs as a Full Moon.
Blue Moon
The largest known structure on Mercury, formed from an asteroid impact.
Caloris Basin
Long, sinuous forms on Venus and Mars, preserved in regions of subdued relief.
Canali
Chondrites made up of undifferentiated silicates with compounds of carbon and water, representing primordial Solar System material.
Carbonaceous chondrites
A gap or space observed between the A and B segments of Saturn’s rings.
Cassini Division
The projection of a reference object’s equator onto the celestial sphere.
Celestial Equator
The imaginary horizontal line separating two hemispheres.
Celestial Horizon
Imaginary lines that trace a reference object’s axis in space.
Celestial Pole
An imaginary sphere made up of the upper hemisphere and the lower hemisphere.
Celestial Sphere
A stony meteorite containing spherical granules, called chondrules, made of minerals like olivine and pyroxene.
Chondrite
The region of the solar atmosphere between the photosphere and the corona, with temperatures ranging from 4500 K to 8500 K.
Chromosphere
Stars that never set below the horizon due to their proximity to the celestial pole.
Circumpolar Stars
The brightest of the three twilight phases, when the Sun is below the horizon but still lights up the sky.
Civil Twilight
A roughly spherical region of diffuse gas surrounding the nucleus of a comet.
Coma
Frozen leftover pieces from the formation of the Solar System, composed of dust, rock, and ice, with a glowing head and tail.
Comet
A phenomenon where two astronomical objects appear close to each other in the sky.
Conjunction
A traditionally defined group of stars identified through patterns, now defined by the International Astronomical Union as a two-dimensional area in space.
Constellation
The outer 30% of the Sun’s radius where heat is transferred via convection currents.
Convection Zone
The current basis for the 24-hour time zone system, created by the International Meridian Conference in 1884.
Coordinated Universal Time (UTC)
The outermost portion of the Sun’s atmosphere, visible during a Solar Eclipse.
Corona
A small asteroid that orbits a larger asteroid, providing the first evidence that asteroids may have tiny moons.
Dactyl
The transition from night to day as the sky brightens, classified as civil, nautical, and astronomical.
Dawn
The practice of setting clocks forward one hour during summer and back in autumn to utilize natural daylight.
Daylight Saving Time (DST)
The irregularly shaped, dark-colored moon of Mars.
Deimos
A tide cycle where there is only one high tide and one low tide in a day.
Diurnal tide
The transition from day to night as the sky darkens, classified as civil, nautical, and astronomical.
Dusk
A celestial body that orbits a star, has enough mass for a nearly round shape, but hasn’t cleared its orbital path.
Dwarf planet
A dull glow when sunlight reflects off Earth’s surface, illuminating the unlit portion of the Moon, best seen around the New Moon.
Earthshine
The change from high to low tide, also known as an ebb current.
Ebb tide
An astronomical event where one celestial body partially or fully covers another.
Eclipse
The imaginary plane that traces the Sun’s apparent path across the sky or the projection of Earth’s orbit onto the celestial sphere.
Ecliptic Plane
A British astronomer who predicted the return of a comet, later named after him.
Edmond Halley
The angle an object makes with the horizon, also referred to as altitude.
Elevation
A spring tide that occurs during either the Autumnal or Vernal equinox.
Equinoctial spring tide
A phenomenon occurring twice a year when the Sun is directly over the Earth’s equator, making day and night lengths nearly equal.
Equinox
A rare optical phenomenon at dawn or dusk, where sunlight reflects off cosmic dust, creating a hazy light extending from the horizon.
False Dawn
The second primary Moon phase, when the Moon has reached the first quarter of its orbit, with 50% of its surface illuminated.
First Quarter Moon
The change from low to high tide, also known as flood current.
Flood tide
The final primary Moon phase when the entire face of the Moon is lit.
Full Moon
A massive collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
Galaxy
An Italian mathematician, astronomer, and physicist who first used a telescope to observe celestial bodies, discovering moons of Jupiter, Venus’ phases, and more.
Galileo Galilei
An American astronomer who proposed the Kuiper Belt as the source of short-period comets.
Gerard Peter Kuiper
A spherical group of stars located in the halo of galaxies.
Globular cluster
Energy stored in a system due to the force of gravity.
Gravitational Potential Energy
Any circle formed by a plane passing through the center of Earth, like the equator and meridians.
Great Circle
A conjunction of Jupiter and Saturn.
Great Conjunction
A large, persistent storm on Jupiter, rotating counter-clockwise.
Great Red Spot
The mean solar time at the Prime Meridian, also referred to as GMT.
Greenwich Mean Time (GMT)
A phase of the Moon where 50% of its surface is illuminated, also known as First Quarter or Third Quarter Moon.
Half Moon
A natural phenomenon where ice crystals in the sky refract light, creating a halo around the Sun or Moon.
Halo
The vertical distance from Earth’s surface.
Height
The theory proposed by Nicolaus Copernicus, stating that Earth and the other planets orbit the Sun.
Heliocentric Theory
The highest point a tide reaches.
High tide
A coordinate system used to describe the position of objects in the sky based on altitude and azimuth, ignoring distance.
Horizontal Coordinate System
A 98-inch space telescope in Earth’s orbit, named after Edwin Hubble, equipped with infrared and X-ray sensors.
Hubble Space Telescope (HST)
A rare solar eclipse where an Annular Eclipse transitions to a Total Solar Eclipse, or vice-versa.
Hybrid Solar Eclipse
A depression formed by the impact of a projectile.
Impact crater
An imaginary line that zigzags through the antimeridian, marking the boundary between one day and the next.
International Date Line (IDL)
The gas giant planets of our Solar System: Jupiter, Saturn, Uranus, and Neptune.
Jovian planets
A solstice in June marking the longest day of the year in the Northern Hemisphere and the shortest in the Southern Hemisphere.
June Solstice
A region of icy bodies beyond Neptune, proposed by Gerard Peter Kuiper, where Pluto is located.
Kuiper Belt
Imaginary horizontal lines used to locate points on Earth’s surface, part of the geographical coordinate system.
Latitude
An atmospheric phenomenon where light reflects off ice crystals, forming pillars of light.
Light pillars
A unit of distance defined as the distance light travels in a vacuum in one year, roughly 9.5 trillion kilometers or 6 trillion miles.
Light-year
The apparent outer edge of a lunar or planetary disk.
Limb
Another term for the International Date Line (IDL), which defines the boundary between one day and the next.
Line of Demarcation
Occurs when the Sun crosses the meridian below the horizon, marking the middle of the night.
Local Midnight
Imaginary vertical lines used to locate points on Earth’s surface, part of the geographical coordinate system.
Longitude
The lowest point a tide reaches.
Low tide
The lower part of the celestial sphere below a reference object.
Lower hemisphere
The point in the Moon’s orbit farthest from Earth.
Lunar Apogee
A phenomenon where the Earth blocks sunlight from reaching the Moon, casting a shadow on it.
Lunar Eclipse
The time it takes for the Moon to complete its phases, from one New Moon to the next.
Lunar Month
A rainbow caused by the Moon’s light reflecting and refracting through water droplets in the air.
Lunar rainbow
Another term for Lunar Month or Synodic Month, which is the time it takes the Moon to complete its phases.
Lunation
The difference between true north and magnetic north.
Magnetic Declination
The region of space controlled by Earth’s magnetic field, modified by the solar wind.
Magnetosphere
The equinox that occurs in March, marking the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.
March Equinox
A dark, low-lying plain on the Moon, filled with volcanic rocks.
Mare
The highest peak on Venus, located within the Ishtar Terra region.
Maxwell Montes
A half circle of longitude that is perpendicular to the latitude lines.
Meridian
A phenomenon where numerous meteors flash across the sky over several days or weeks.
Meteor Shower
A remnant of a meteor that survives its passage through the atmosphere and lands on Earth.
Meteorite
Rocky objects in space, ranging in size from dust grains to small asteroids.
Meteoroids
The fireballs caused by meteoroids burning up in Earth’s atmosphere.
Meteors
A phenomenon where a Full Moon or New Moon coincides with the Moon being at its farthest point from Earth (Apogee).
Micromoon
The phenomenon of 24-hour daylight that occurs within or near polar circles, opposite of Polar Midnight.
Midnight Sun
A rocky, airless remnant from the early formation of the Solar System, typically found in the asteroid belt.
Minor planet
A tide cycle where there are two high and low tides of different heights in a day.
Mixed semidiurnal tide
The second Full Moon in a calendar month with two Full Moons.
Monthly Blue Moon
A natural satellite that orbits a planet or asteroid.
Moon
A rainbow caused by the Moon’s light reflecting and refracting through water droplets.
Moonbow
The moment when the upper edge of the Moon becomes visible above the horizon.
Moonrise
The moment when the upper edge of the Moon disappears below the horizon.
Moonset
The point in the celestial coordinate system directly below a reference object.
Nadir
The second twilight phase where both the horizon and brighter stars are visible for navigation.
Nautical Twilight
A period of moderate tides occurring when the Sun and Moon are at right angles.
Neap tide
An elementary particle with little or no mass that carries energy from nuclear reactions.
Neutrino
The first primary Moon phase when the Sun and Moon are aligned, with the Moon’s dark side facing Earth.
New Moon
A Polish astronomer who proposed the heliocentric theory.
Nicolaus Copernicus
The local time in a country or region that doesn’t use Daylight Saving Time.
Normal time
The auroras that occur in the Arctic Circle.
Northern Lights
The frozen core of a comet, containing almost the entire mass of the comet.
Nucleus
The angle of tilt of an object’s axis relative to its orbital plane.
Obliquity
The path an object takes around another due to gravity.
Orbit
A rare atmospheric optical phenomenon where white bands appear in the sky at the Sun or Moon’s level.
Parhelic Circle
A type of lunar eclipse where only part of the Moon is obscured by Earth’s shadow.
Partial Lunar Eclipse
A type of solar eclipse where the Moon partially covers the Sun.
Partial Solar Eclipse
A shallow crater with a scalloped edge.
Patera
The outer part of the shadow during an eclipse.
Penumbra
A type of lunar eclipse where the Moon passes through the faint outer shadow of Earth.
Penumbral Lunar Eclipse
A spring tide that occurs during a Supermoon, resulting in larger tidal variations.
Perigean spring tide
The point in Earth’s orbit closest to the Sun.
Perihelion
The larger of Mars’ two moons, irregularly shaped and dark-colored.
Phobos
The visible surface of the Sun, where light is emitted, with a temperature of around 5800 K.
Photosphere
A celestial body that orbits a star, is round due to its gravity, and has cleared its orbital path.
Planet
A phenomenon where a planet crosses between Earth and the Sun.
Planet Transit
A dull glow from sunlight reflecting off a planet, illuminating its moon’s dark side.
Planetshine
The phenomenon of 24-hour daylight, occurring near polar circles, opposite of Polar Midnight.
Polar Day
rocky, airless remnant left over from the early formation of our Solar System about 4.6 billion years ago, mostly found in the main asteroid belt between Mars and Jupiter.
Minor planet (Asteroid)
A cycle with two high tides and low tides within a day, differing in heights.
Mixed semidiurnal tide
The second Full Moon in a calendar month that has two Full Moons.
Monthly Blue Moon
A natural satellite that orbits planets and asteroids in our Solar System.
Moon
A natural phenomenon occurring when the Moon’s light is reflected and refracted off water droplets in the air.
Moonbow (Lunar rainbow)
The moment the upper edge of the Moon becomes visible above the horizon.
Moonrise
The moment the upper edge of the Moon disappears below the horizon.
Moonset
The point in celestial coordinate systems that is exactly below a reference object.
Nadir
The second of the three twilight phases when both the horizon and the brighter stars are usually visible, allowing navigation at sea.
Nautical Twilight
A period of moderate tides occurring due to the Sun and Moon being at right angles to each other, appearing seven days after a spring tide.
Neap tide
An elementary particle with little or no rest mass and no charge, carrying energy from a nuclear reaction.
Neutrino
The first primary Moon phase occurring when the Sun and Moon are aligned, with the Sun and Earth on opposite sides of the Moon.
New Moon
A Polish astronomer who proposed the heliocentric theory that the Earth and other planets revolve around the Sun.
Nicolaus Copernicus
The local time in a country or region that does not use Daylight Saving Time.
Normal time (Standard Time)
Auroras that occur in the Arctic Circle.
Northern Lights (Aurora Borealis)
The frozen core of a comet, containing almost the entire cometary mass, located in the comet’s head.
Nucleus
The angle of tilt of an object from its orbital plane.
Obliquity (Axial Tilt)
The path of an object around a point or another object in space, resulting from their gravitational pull.
Orbit
A rare optical atmospheric phenomenon appearing as white, circular bands in the sky at the same level as the Sun or Moon.
Parhelic Circle
A type of Lunar Eclipse where only part of the Moon’s surface is obscured by Earth’s umbra.
Partial Lunar Eclipse
A type of Solar Eclipse that occurs when the Moon only partially covers the Sun as observed from Earth.
Partial Solar Eclipse
A shallow crater with a scalloped, complex edge.
Patera
The outer part of an eclipse’s shadow.
Penumbra
A type of Lunar Eclipse occurring when the Moon travels through the faint penumbral part of Earth’s shadow.
Penumbral Lunar Eclipse
A spring tide occurring during a Supermoon, causing a larger variation between high and low tides.
Perigean spring tide
The point on Earth’s elliptical orbit closest to the Sun.
Perihelion
The irregularly-shaped, dark-colored moon of Mars, larger than its companion moon, Deimos.
Phobos
The visible “surface” of the Sun with temperatures of about 5800 K and an average thickness of 400 km, which radiates light into space.
Photosphere
A celestial body in orbit around a star, having sufficient mass for self-gravity to assume a nearly rounded shape and having cleared its orbital neighborhood.
Planet
A phenomenon occurring when a planet comes between Earth and the Sun.
Planet Transit
A dull glow occurring when sunlight reflects off a planet’s surface, illuminating the unlit portion of its moon’s surface.
Planetshine
An extended period of daytime lasting more than 24 hours, happening only within or near polar circles, beginning during the sunrise of the Vernal Equinox in March in the Northern Hemisphere.
Polar Day (Midnight Sun)
The opposite of Polar Day, when none of the Sun’s disc is visible above the horizon, occurring only within polar circles.
Polar Midnight
The main longitudinal reference point set as 0° longitude, located through Greenwich, England.
Prime Meridian
A celestial object of small angular size that emits pulses of radio waves at regular intervals.
Pulsar
The inner 70% of the Sun’s radius, where heat from fusion reactions is radiated toward the surface at varying temperatures.
Radiative Zone
The apparent change in the movement of a planet through the sky due to the relative positions of the planet and Earth.
Retrograde motion
A thin, disk-like accumulation of small grains of rock and ice, likely originating from the tidal force-induced breakup of nearby moons.
Ring
An object, such as the Moon, in orbit around a reference object.
Satellite
The third Full Moon of an astronomical season with four Full Moons.
Seasonal Blue Moon
A cycle with two high tides and low tides of about the same height within a day.
Semidiurnal tide
An equinox occurring during September, considered the Autumnal Equinox in the Northern Hemisphere and the Vernal Equinox in the Southern Hemisphere.
September Equinox
The fireballs of meteoroids that burn up upon entering Earth’s atmosphere.
Shooting stars (Meteors)
A phenomenon where the Moon moves between the Earth and the Sun, casting a shadow on the Earth’s surface.
Solar Eclipse
Eruptions of solar material beyond the disk of the Sun.
Solar prominences
A continuous stream of highly energized particles, mostly electrons and protons, flowing out from the Sun through space.
Solar wind
The time it takes Earth to complete a full orbit around the Sun.
Solar Year (Tropical year)
A phenomenon occurring twice every year when the Sun appears in the sky for a longer period, making the day longer.
Solstice
Auroras that occur in the Antarctic Circle.
Southern Lights (Aurora Australis)
A narrow jet of gas in the Sun’s chromosphere extending into the corona.
Spicules
Faint, dark areas perpendicular to Saturn’s rings that seem to grow and shrink.
Spokes
A kind of tide occurring during Full or New Moons, increasing average tidal ranges due to the gravitational pull of the Sun and Moon.
Spring tide (King tide)
The local time in a country or region that does not use Daylight Saving Time.
Standard Time (Winter time)
Meteorites comprised of differentiated igneous silicates plus iron and nickel metal.
Stony-iron meteorites
A kind of tide occurring during storms, where seawater levels increase due to a combination of storm surge and normal tidal movement.
Storm tide
A solstice occurring in June in the Northern Hemisphere and December in the Southern Hemisphere, marking the start of the Summer season.
Summer Solstice
The practice of setting clocks forward one hour during summer months and back in autumn to make better use of natural daylight.
Summer time (Daylight-Saving Time)
A natural phenomenon with glowing spots around the sun, caused by sunlight refracting off ice crystals in cirrus clouds, most visible near the horizon.
Sundog
The moment the upper edge of the solar disk becomes visible above the horizon.
Sunrise
The moment the upper edge of the solar disk disappears below the horizon.
Sunset
Magnetically-induced features of the photosphere that are temporarily cool and dark compared to surrounding regions.
Sunspots
A phenomenon when a Full Moon or New Moon coincides with a Perigee.
Supermoon
The time it takes the Moon to pass through all its phases, measured from one New Moon to the next.
Synodic month (Lunar Month)
A phenomenon where three or more celestial bodies align in a roughly straight line.
Syzygy
Small, rounded pieces of silicate glass believed to have become airborne during terrestrial impact events.
Tektites
The line separating the illuminated and unilluminated parts of a celestial body, dividing day and night.
Terminator
Rocky planets of the Solar System, including Mercury, Venus, Earth, and Mars.
Terrestrial planets
A theory proposing that a tremendous release of energy in an event, the “Big Bang,” initiated the formation of all matter approximately 15 billion years ago.
The Big Bang Theory
The final primary Moon phase defined as the moment the Moon has reached the third quarter of its orbit around Earth, with 50% of its surface illuminated.
Third Quarter Moon (Half Moon)
The time that passes between the passage of the Moon and the onset of high tide.
Tidal lag
The difference in water level between a high tide and a low tide.
Tidal range
The rise or fall of ocean level due to the Moon’s gravitational pull.
Tide
Irregular zones indicating the local standard time of a region or country.
Time Zone
A type of Lunar Eclipse occurring when Earth’s umbra covers all of the Moon’s surface.
Total Lunar Eclipse
A type of Solar Eclipse that occurs when the Moon completely covers the Sun as observed from Earth within a limited area.
Total Solar Eclipse
The latitude 23°26’ N marking the northern-most position on Earth where the Sun is directly overhead at least once a year, during the June Solstice.
Tropic of Cancer
The latitude 23°26’ S marking the southern-most position on Earth where the Sun is directly overhead at least once a year, during the December Solstice.
Tropic of Capricorn
The time it takes Earth to complete a full orbit around the Sun.
Tropical Year (Solar year)
The time between day and night when there is light outside, but the Sun is below the horizon, divided into civil, nautical, and astronomical twilight.
Twilight
The darkest part of an eclipse’s shadow.
Umbra
The upper part or the visible part of the sky from a reference object in the horizontal coordinate system.
Upper hemisphere
Coordinated Universal Time, the basis for the 24-hour time zone system created by the International Meridian Conference in 1884.
UTC
An equinox occurring in March, marking the Spring season in the Southern Hemisphere and the Autumnal Equinox in the Northern Hemisphere.
Vernal Equinox
The final intermediate Moon phase occurring after the Third Quarter Moon where less than half of the Moon’s surface is still visible, sometimes showing earthshine.
Waning Crescent Moon
The third intermediate Moon phase after the Full Moon where more than half of the Moon’s surface is still illuminated.
Waning Gibbous Moon
The first intermediate Moon phase that begins when a thin sliver of the Moon becomes visible after New Moon.
Waxing Crescent Moon
The second intermediate Moon phase that lasts until the Full Moon.
Waxing Gibbous Moon
A solstice occurring in December in the Northern Hemisphere and June in the Southern Hemisphere, marking the beginning of the Winter season in both hemispheres.
Winter Solstice
The local time in a country or region that does not use Daylight Saving Time.
Winter time (Standard Time)
A sinuous, irregular, segmented, apparently smooth elevation occurring within the borders of a mare region of the Moon’s surface, characterized by dike-like outcrops, crest-top craters, and longitudinal rifts.
Wrinkle edges
The point directly above a reference object in celestial coordinate systems.
Zenith
A rare optical phenomenon occurring around sunset or sunrise when sunlight reflects off tiny space particles or cosmic dust, creating a hazy light extending from the horizon.
Zodiac Light (False Dawn)
Thick rotating clouds that swirl on planets like Jupiter, blowing in opposite directions in adjacent bands.
Zones
