Preface words to know (Planetary Science)

Solar Eclipse

A celestial alignment where a planetary moon passes directly between its host star and the planet, temporarily obscuring the star’s light and casting a shadow on the planet’s surface.

Lunar Eclipse

A celestial event that occurs when Earth passes directly between the sun and the Moon, causing Earth’s shadow to fall across the lunar surface (only happened during the full moon phase).

Umbra

The darkest, central part of a shadow cast by a celestial body where all direct light from the illuminating source (like the sun) is completely blocked.

Penumbra

The partially shaded, outer region of a shadow cast by a celestial body during an eclipse (Usually a partial eclipse).

Ecliptic Plane

The imaginary, flat, two-dimensional disk defined by Earth’s orbit around the Sun.

Arctic Circle

The parallel of latitude approximately 66 degrees 33’ N of the equator. It defines the coundary where the sub-solar point never reaches the horizon for at least one full day during the summer (midnight sun) and does not rise for at least one full day during thewinter (polar night).

Tropic of Cancer

The northernmost latitude ( 23 degrees 26’ N) on Earth where the Sun can appear directly overhead at noon, occuring during the June solstice.

Equator

An imaginary great circle around a celestial body.

Tropic of Capricorn

The southernmost circle of latitude ( 23 degrees 26’22’’ S) where the Sun can appear directly overhead at local noon. It marks the exact latitude of the subsolar point during the December Solstice.

Antarctic Circle

Serves as a primary hub for planetary science due to its extreme environment, acting as a natural laboratory for Mars-analogue permafrost, a repository for extraterrestrial meteorites, and a unique staging ground for space mission simulations.