Star position

The position of a star tells us where it appears in the sky, similar to how we use coordinates like latitude and longitude on Earth. In astronomy, the three main coordinates are right ascension, declination and distance. 

Right ascension is like longitude for the sky — it tells us how far east a star is along the celestial equator. It’s usually measured in hours, minutes, and seconds, because the sky appears to rotate once every 24 hours.
Declination is like latitude — it tells us how far north or south a star is from the celestial equator. A star with a positive declination is in the northern sky, while a star with a negative declination is in the southern sky.

To find out how far away a star is, astronomers often use the star's parallax. As Earth moves around the Sun, nearby stars appear to shift slightly in position compared to distant background stars. Measuring this small shift allows scientists to calculate the star’s distance — the smaller the parallax, the farther away the star is.

Stellar distances are usually expressed in light-years and parsecs. A light-year is the distance light travels in one year — about 9.46 trillion kilometers (5.88 trillion miles). A parsec is equal to about 3.26 light-years and is commonly used in scientific measurements.

In the Stellar Catalog, stars are listed with accurate position data from the Gaia catalog, including right ascension, declination, and distance in light-years, calculated from parallax.