💿Accretion Disk

A rotating disk of matter spiraling into a massive object.

🪨Asteroid

A small rocky body orbiting the Sun, mostly between Mars and Jupiter.

🪨Asteroid Belt

The region between Mars and Jupiter populated by numerous asteroids.

🧬Astrobiology

The study of the origin, evolution, and distribution of life in the universe.

📐Astrometry

The precise measurement of the positions and movements of celestial bodies.

📏Astronomical Unit

The average distance between Earth and the Sun, about 150 million km.

⚛️Astrophysics

The branch of physics that explains the nature of celestial objects.

🌌Aurora

A natural light display caused by solar particles interacting with the magnetosphere.

💥Big Bang

The prevailing model describing the origin and expansion of the universe.

🕳️Black Hole

A region of spacetime from which nothing, not even light, can escape.

🌐Celestial Sphere

An imaginary sphere onto which celestial objects are projected for mapping.

📶Cepheid Variable

A pulsating star whose period correlates with its intrinsic brightness.

☄️Comet

An icy body that releases gas and dust when near the Sun.

✨Constellation

A recognized pattern of stars forming a named region of the sky.

🌋Coronal Mass Ejection

A large release of plasma and magnetic field from the Sun's corona.

🪜Cosmic Distance Ladder

A series of methods used to measure distances to celestial objects.

📡Cosmic Microwave Background

Faint radiation left over from the early universe, about 13.8 billion years old.

🔭Cosmology

The study of the origin, structure, and evolution of the universe.

⚡Dark Energy

A mysterious force driving the accelerating expansion of the universe.

🕳️Dark Matter

A hypothetical form of matter that does not emit light but affects gravity.

📏Declination

The celestial equivalent of latitude, measured north or south of the equator.

🔵Dwarf Planet

A round body orbiting the Sun that has not cleared its orbital neighborhood.

🌘Eclipse

The alignment of three celestial bodies causing one to be obscured.

🛤️Ecliptic

The apparent annual path of the Sun across the celestial sphere.

➖Equator

The great circle on the celestial sphere equidistant from the poles.

⚖️Equinox

The moment when day and night are approximately equal in length.

🚫Event Horizon

The boundary around a black hole beyond which escape is impossible.

🌍Exoplanet

A planet orbiting a star outside our solar system.

🌌Galaxy

A gravitationally bound system of stars, gas, dust, and dark matter.

🌌Galaxy Cluster

A gravitationally bound collection of hundreds to thousands of galaxies.