HOW TO visualize approximate radial distance from a fixed point on a map

The Twitter Location Search app utilizes Google Maps to show approximate radial distance from a specified point on a map

If you are an API developer, this tool can be useful to visualize approximate radial distance while dealing with location-specific queries.

The Twitter Search API supports a parameter called geocode that returns tweets by users located within a given radius of the given latitude/longitude for a given search term.

The parameter value is specified by "latitude,longitude,radius", where radius units must be specified as either "mi" (miles) or "km" (kilometers).

The maximum limit for the radius is not specified in the API docs but the Advanced Search feature on Twitter has 1000 as the upper limit.