which two things are needed to determine a standard candle distance from earth
Cosmic distance ladder Almost all astronomical objects used as physical distance indicators belong to a class that has a known brightness. By comparing this known luminosity to an object's observed brightness, the distance to the object can be computed using the inverse-square law. These objects of known brightness are termed standard candles.
Land's End to John o' Groats The straight-line distance from Land's End to John o' Groats is 603 miles (970Â km) as determined from O.S. Grid References, but such a route passes over a series of stretches of water in the Irish Sea. Google Earth reports a distance of 602.70 miles between the two iconic marker points.