# AstroAngularSeparation

AstroAngularSeparation[astro1,astro2]

gives the angular distance on the celestial sphere between the astronomical objects astro1 and astro2, as observed from your current geo location.

AstroAngularSeparation[astro1,astro2,observer]

gives the angular distance between astro1 and astro2 as perceived by the given observer.

# Details • Astro angular separation is also known as angular distance, and as apparent separation or distance.
• AstroAngularSeparation computes angles on the celestial sphere between any two objects, positions or directions, from any location in the solar system; by default, your current geo location.
• AstroAngularSeparation[astro1,astro2] is equivalent to AstroAngularSeparation[astro1,astro2,{"frame",Now,Here}] for any "frame".
• In AstroAngularSeparation[astro1,astro2,], the astroi can be astronomical Entity objects such as , AstroPosition objects or named directions such as "Zenith".
• In AstroAngularSeparation[astro1,astro2,observer], the observer argument can be any reference frame specification. If an observation location is not given, Here will be assumed. If an observation date is not given, Now will be assumed.
• returns a Quantity angle with angular degrees unit.

# Examples

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## Basic Examples(3)

Compute the current angular distance between the Sun and the Moon, as observed from your location:

Compute their angular separation as observed from the antipodes of your location:

Plot the angular separation between Jupiter and Saturn between years 2000 and 2040:

Plot the angular separation between the Earth and the Sun as observed from Pluto:

## Scope(3)

Compute the angular separation between two local named directions:

Find the current angle between the direction to the true equinox and the local north direction:

Plot its evolution over a few days:

AstroAngularSeparation is listable in its first two arguments:

## Applications(2)

Visualize nutation effects, in arcseconds:

Eddington's observations of gravitational light deflection were performed approximately on this date and location:

Visualize what happened during the eclipse, centering around the position of the Sun:

This gives the observed position of the star HIP20842, also known as HR1403, in Taurus, the constellation the Sun was in on that date:

Compute the angular separation in arcseconds between the positions corrected and not corrected for gravitational deflection:

This is approximately what Eddington measured:

This is the value for the deflection of a star that grazes the edge of the solar disk:

## Properties & Relations(2)

Angles between any two cardinal directions are fixed:

The angular separation between the CIO (celestial intermediate origin) and the true equinox is called the equation of origins: