help

Can a Person Observe a Quasar as it Appeared Later in its Life?

-- | February 28, 2017

Question: I am a high school student and very interested in astronomy I’m only a freshman but have had several theory’s one was about quasars but today is if a quasar has sent light that is seen today the light is from the past showing the quasar from billions of years ago is it possible to intercept the light to see the quasar later in its life. If there is a quasar in the middle of the universe ( this is just a way for u to visualize what I am saying) and then earth and we are seeing the quasar through the telescope what if we jumped half way between earth and the quasar would we be able to see the quasar more later in its life so by doing this also determine the age of it by getting closer and closer to the quasar until it’s last dying light. Just to remind u I’m a freshman in high school i don’t know if this makes sense I’m just trying to figure stuff out. Please help me if you can. — Jensen

Answer: As you surmised, it is the “universal speed limit” imposed by the speed of light which dictates how we see objects in the universe. The light from objects which are further away from us appear younger to us since the light that we receive from them now was emitted a very long time ago. Using your example of a distant quasar, if we were instead positioned closer to it than we are today, we would receive the light emitted from the quasar sooner, so would be observing it as it was later in its life. So, you are correct if you assume that Earth was originally positioned closer to the quasar. Thinking about this as a “jump” to a position between the Earth and the quasar would involve some faster-than-light travel which, unfortunately, is not allowed.

Jeff Mangum

The National Radio Astronomy Observatory is a facility of the U.S. 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 U.S. 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.