cosmic distance ladder wikipedia - EAS
Cosmic distance ladder - Wikipedia
https://en.wikipedia.org/wiki/Cosmic_distance_ladderThe 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 …
Distance measure - Wikipedia
https://en.wikipedia.org/wiki/Distance_measureDistance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to …