Concepts in Astronomy #4. Right AscensionsteemCreated with Sketch.

in #astronomy6 years ago (edited)

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Right Ascension

The Right Ascension (RA) is the angular distance (in hours, minutes and seconds of arc)measured eastward along the celestial equator, from the position of the Sun at the March equinox (0h0min0sec) to the position we want to map in the celestial sphere. It increases due East. It is the equivalent of the longitude in an Earth's map.

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When the plane of the ecliptic is projected in the celestial sphere (pathway of the sun), it will cross the celestial equator in 2 points (the equinoxes). The point of the March equinox marks 0h RA. Just as in the terrestrial coordinates the line of 0h RA goes from the north celestial pole to the south celestial pole.

Previous Posts

Concepts in Astronomy #1. Introduction
Concepts in Astronomy #2. The Ecliptic
Concepts in Astronomy #3. The Celestial Equator

Credits
- Galaxy image obtained from Pixabay under CC0. No Copyright. The person who associated a work with this deed has dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law
- RA and Dec in Celestial Sphere image obtained from Wikipedia under CC BY-SA 3.0. Author:Tfr000

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