Astronomy Concepts

Apparent magnitude measures how bright an object appears from Earth, with lower/negative values being brighter.

Declination (Dec, δ) is celestial latitude—angular distance north (+) or south (-) of the celestial equator, analogous t...

An equinox occurs when the Sun crosses the celestial equator, making day and night approximately equal length everywhere...

The nadir is the point directly below the observer (altitude = -90°), opposite the zenith.

Right Ascension (RA, α) is celestial longitude—angular distance eastward along celestial equator from the vernal equinox...

A solstice occurs when the Sun reaches its northernmost or southernmost point in the sky, marking the longest and shorte...

The zenith is the point directly overhead (altitude = 90°), the highest point in an observer's sky.