There are no roads in the sky, so knowing an object's coordinates is crucial to finding it in your telescope. Declination corresponds to latitude and right ascension to longitude. Like cities, every object in the sky has two numbers that fix its location called right ascension and declination, more generally referred to as the object's celestial coordinates. Every location, whether it be a city, airport, or even your own home or apartment building lies somewhere on the worldwide coordinate grid (below), its location fixed by two numbers.Įvery city on the planet has a unique latitude and longitude, its "spot" on the grid.
![circular celestial navigation calculator circular celestial navigation calculator](http://www.nauticalcalculator.com/assets/images/altitude-correction-for-air-temperature-1242x2208.png)
A negative sign in front of the latitude indicates south and a positive sign north. Or Wonglepong, Australia, situated along that continent's east coast at –27.0° south, 153.2° east. Take Tuscaloosa, Alabama, for example, which is located at latitude +33.2° north, longitude 87.6° west. It defines the the zero (0°) longitude line just as the equator defines the 0° latitude line.Įach city has a unique latitude and longitude. The prime meridian is an imaginary line that runs through the Royal Observatory in Greenwich, United Kingdom, and extends to the North and South Poles. To find anyplace on the globe of Earth, you only need to know its latitude, the distance in degrees north or south of the equator, and longitude, the distance in degrees east or west of the prime meridian. Then I realized they were just numbers like latitude and longitude, except applied to the stars.
![circular celestial navigation calculator circular celestial navigation calculator](https://1.bp.blogspot.com/-_3jwdWI5Emo/WfOeV5psTcI/AAAAAAAADg4/vpFmc7dMey0ofy6l7jI9pkmfBe6I8ws5gCLcBGAs/s1600/DR%2Bplot%2Bprob%2B26.png)
When I got started in astronomy at age 11, they were a little scary. Sooner or later every novice skywatcher runs into the terms RA and Dec., short for right ascension and declination. The sky is draped in an invisible coordinate grid that will help you easily find any object you wish, the same as you would locate a city on a map.