Celestial Sphere Lecture Notes

These flashcards cover key vocabulary and concepts from the Intro Astronomy lecture notes.

Celestial Sphere

An imaginary sphere that all the stars are fixed to and can rotate about the Earth.

Altitude

An angular measurement from 0° at the horizon to 90° at the Zenith and -90° at the Nadir.

Azimuth

An angular measurement about the horizon, starting at 0°/North, and measured in degrees.

Equatorial System

A coordinate system that uses lines of latitude and longitude projected onto the celestial sphere.

The Vernal Equinox

The point at which the Sun crosses the celestial equator, marking the beginning of spring in the Northern Hemisphere.

Circumpolar Stars

Stars that never rise or set, located in the circumpolar cap.

Daily Motion of the Stars and Sun

Stars and the Sun rise in the east and set in the west due to Earth's rotation.

Right Ascension

An angular measurement in hours marked along the celestial equator, correlating with the Earth's rotation.

Declination

The celestial equivalent of latitude, ranging from 0° at the Celestial Equator to 90° at the North Celestial Pole.

Small Angle Approximation

A formula used to relate an object’s apparent size, true size, and distance based on geometry.