Transcript: In cosmology galaxies are used as markers of expanding space. In addition to the overall cosmic expansion gravity has caused matter to clump or cluster on many different scales. In addition to the gravitational attraction that caused galaxies to collapse and form in the first place...

Transcript: Most of the techniques for measuring distance in astronomy depend on well understood properties of stars or entire galaxies. However, if astronomers believe they’ve measured the current expansion rate of the universe then redshift itself can be used to indicate distance. Redshift is...

Transcript: When a massive star dies the supernova that results can rival an entire galaxy in brightness, so it can be seen to a very large distance, a billion lightyears or more. When a single massive star dies it does not do so in a well regulated way, but the supernovae that result from a...