# Right ascension

Also called: RA.

The sky's “longitude”, measured eastward in hours, minutes and seconds (0h to 24h).

Right ascension is measured from the point where the Sun crosses the celestial equator in March. It's counted in hours because the sky turns once a day: an object 1h further east in right ascension crosses the [meridian](https://astropilot.space/glossary/meridian) an hour later.

**In AstroPilot:** Object pages give the right ascension and [declination](https://astropilot.space/glossary/declination) for the [J2000](https://astropilot.space/glossary/epoch) epoch.

**Related:** [Declination](https://astropilot.space/glossary/declination.md), [Celestial sphere](https://astropilot.space/glossary/celestial-sphere.md), [Epoch (J2000)](https://astropilot.space/glossary/epoch.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/right-ascension