<P> The cosmic distance ladder ( also known as the extragalactic distance scale ) is the succession of methods by which astronomers determine the distances to celestial objects . A real direct distance measurement of an astronomical object is possible only for those objects that are `` close enough '' ( within about a thousand parsecs ) to Earth . The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances . Several methods rely on a standard candle , which is an astronomical object that has a known luminosity . </P>
<P> The cosmic distance ladder ( also known as the extragalactic distance scale ) is the succession of methods by which astronomers determine the distances to celestial objects . A real direct distance measurement of an astronomical object is possible only for those objects that are `` close enough '' ( within about a thousand parsecs ) to Earth . The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances and methods that work at larger distances . Several methods rely on a standard candle , which is an astronomical object that has a known luminosity . </P>
how do we measure the distance to other galaxies
how do we measure the distance to other galaxies
cosmic distance ladder
cosmic distance ladder