How Do Astronomers Measure the Size of the Universe?

-- | September 26, 2012

Question: I’m 15 years old. I want to know how do scientists measure the size of universe or observable universe. — Hassan

Answer: There are several techniques that astronomers use to measure distances in the Universe. Most of these distance measurement techniques build upon other distance measurement techniques, giving us a distance measurement “ladder”. There is a very nice short video explanation of how scientists measure the size of the Universe from the Royal Greenwich Observatory that really does a great job of explaining this distance ladder, and how astronomers measure the size of the Universe. If you want even more information on cosmic distances, check out Dave Goldberg’s “Ask a Physicist” column describing how we measure the size of the universe. I hope that this answers your question.

Jeff Mangum

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
	Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.
	The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."
	AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.