Chapter 4, Problem 1E

Discuss how latitude and longitude on Earth are similar to declination and right ascension in the sky.

To determine

To discuss:

Similarity between the declination and right ascension in the skyand the latitude and longitude on Earth.

Explanation of Solution

Introduction:

For locating any point or place on Earth, a mapmaker needs a unique way to identify the location of all features on maps such as landmarks and cities.Similarly, astronomical mapmakers also need a unique way to identify the location of galaxies, stars and other celestial objects.

On Earth, two-dimensionalmapshave been divided into grids and these grids are formed by crisscrossing of horizontal and vertical lines. It is easy to grid any two-dimensional surface but not a spherical one.The scientists have found a unique way of doing it, by dividing Earth by great circles.

Circles passing through North and South poles are termed as longitudes while a set of progressive circles of increasing diameter while moving towards the equator from North or South Pole are known as latitudes.

These are the lines used to locate any point on Earth. Longitude corresponds to East or West direction with respect to prime meridian. Latitude is the angular distance from the Equator to North and South Poles or whether the point is located above or below the equator.

Similarly, if this equator is extended to the celestial sphere, it is termed as celestial equator. RA or (Right ascension) and DEC (Declination) in the sky is like longitude and latitude on the Earth.

Right ascension corresponds to East-West direction in the sky like longitude and measured in hours, minutes and seconds while declination measuresNorth and South direction or point above and below of the Equator like latitude.