Angles on the celestial sphere

1. Mar 2, 2006

Zaphodx57x

Given the right ascension and declination of two objects in the sky. Is there a way to calculate the angle between them?

If so, do right ascension and declination need to be converted to radians or can they retain their units?

2. Mar 2, 2006

matt.o

the formula to measure the angle between 2 objects on the sky given their positions is;

$$\cos\theta = \cos{\delta_1}cos{\delta_2}\cos(\alpha_1-\alpha_2) + \sin{\delta_1}\sin{\delta_2}$$

where $$\delta_1$$ and $$\delta_2$$ are the declinations in degrees or radians and $$\alpha_1$$ and $$\alpha_2$$ are the right-acsensions in radians or degrees.

Last edited: Mar 2, 2006
3. Mar 5, 2006

Zaphodx57x

Thank you much.