I have been reading Cosmology related topics for about eighteen-months. The other day I was reading from the following website: http://wmap.gsfc.nasa.gov/site/faq.html Under Item 2. is this sentence. "Astronomers see galaxies moving apart from one another: space in the universe is stretching." In my eighteen-months of reading Cosmology subjects, this is the first time that I have ever read the word stretching. Every other occurrence, as I recall, used the term expanding. What is the difference, if any, between a stretching or expanding Universe? Thank you in advance to those that respond.