Space Words That Start with A

There are so many astronomical objects out there behaving in mysterious ways that astronomers are still trying to figure out. A brand new set of words and language has to be invented every time something is discovered and that is part of what makes the study of space so interesting. There’s so much out there that is waiting to be found.

The use of mythological and ancient names to name all the objects that are in space has also always given astronomy an air of mystery and wonder that attracts all kinds of people and incentivizes them to look at the sky every night.

There are so many space-related words and terms that it is hard to keep up.

This is why below, we have compiled a list of space words that start with A so you can learn more about the study of the universe. These are words that are related to astronomy and space, if what you are looking for is specifically for name ideas or the names of objects, check out our lists of star names, planets, or constellations. You will also find those sorted by letter.

Absolute MagnitudeMeasure of a celestial object’s intrinsic brightness.
Absolute ZeroLowest possible temperature, 0 Kelvin or -273.15 degrees Celsius.
AccretionProcess of matter accumulating onto a celestial object.
Accretion DiskRotating disk of gas and dust around a central object.
Active Galactic NucleusCentral region of a galaxy with a high-energy output.
Active RegionArea on the Sun’s surface with increased magnetic activity.
Adaptive OpticsTechnology to correct distortions caused by Earth’s atmosphere in telescopes.
AirlockSealed chamber used for entering and exiting a spacecraft in space.
AlbedoReflectivity of a surface, often of a planet or moon.
AldebaranBrightest star in the Taurus constellation.
AlmagestAncient Greek astronomical treatise by Ptolemy.
Alpha CentauriClosest star system to the Solar System.
Altazimuth MountTelescope mount with vertical and horizontal rotation axes.
AltitudeHeight above a reference point, usually Earth’s surface.
AnalemmaFigure-eight shape traced by the Sun’s position over a year.
AndromedaSpiral galaxy nearest to the Milky Way in the Local Group.
Andromeda GalaxySpiral galaxy that is the largest in the Local Group.
Angular DiameterMeasure of the apparent size of an object in the sky.
Angular MomentumMeasure of rotational motion of an object, including celestial bodies.
AnomalyDeviation from the expected orbit of a celestial object.
AntaresBrightest star in the Scorpius constellation.
AntimatterCounterpart to normal matter, composed of antiparticles.
Antipodal PointPoint on the opposite side of a celestial body from another.
ApastronFarthest point of an object’s orbit around another in binary systems.
ApertureDiameter of the opening in a telescope or camera lens.
Aperture SynthesisTechnique combining signals from multiple telescopes to create high-resolution images.
AphelionFarthest point in a planet’s orbit from the Sun.
ApogeeFarthest point of an object’s orbit around another body.
ApolloSeries of US missions that landed astronauts on the Moon.
Apparent MagnitudeBrightness of a celestial object as seen from Earth.
Apparent MotionIllusion of movement of celestial objects due to Earth’s rotation.
AppulseLeast apparent distance between one celestial object and another
ApsisPoint of an object’s orbit closest (periastron) or farthest (apastron) from a center of attraction.
ArcminuteUnit of angular measurement, 1/60th of a degree.
ArcsecondUnit of angular measurement, 1/3600th of a degree.
Ascending NodePoint where an orbit crosses a reference plane from below.
AscensionRight ascension (RA) is a celestial coordinate used to locate objects in the sky.
AsterismGroup of stars forming a recognizable pattern within a constellation.
AsteroidSmall rocky body that orbits the Sun in the asteroid belt.
Asteroid BeltRegion between the orbits of Mars and Jupiter with numerous asteroids.
AsteroseismologyStudy of star interiors through observation of their oscillations.
AsthenospherePart of a planet’s mantle that allows tectonic plate movement.
AstrobiologyStudy of life in the universe and its potential origins.
AstrochemistryStudy of chemical processes in space, especially in interstellar medium.
AstrographTelescope designed for astrophotography.
AstrolabeAncient instrument used to determine celestial positions.
AstrometryPrecise measurement of the positions and motions of celestial objects.
AstronautTrained individual who travels and works in space.
AstronomerScientist who studies celestial objects and phenomena.
Astronomical CalendarCalendar based on astronomical events, like solstices and equinoxes.
Astronomical ClockTimekeeping device that displays astronomical information.
Astronomical TwilightPeriod when the Sun is between 12 and 18 degrees below the horizon.
Astronomical Unit (AU)Average distance between Earth and the Sun (about 93 million miles).
AstronomyScientific study of celestial objects and the universe.
AstrophysicsBranch of astronomy dealing with the physical properties of celestial objects.
AstrostatisticsApplication of statistics to analyze astronomical data.
AtmosphereLayer of gases surrounding a planet or celestial body.
AurorasNatural light displays in the Earth’s polar regions.
Axial TiltAngle between a celestial body’s rotational axis and its orbital axis.
Space words that start with A

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