Proper Motion vs. Expansion

Not open for further replies.


With smaller celestial objects, like stars, astronomers are able to measure their proper motion relative to us.

But the proper motion of an object becomes harder to keep track of when dealing with greater distances. Of course, not only is distance a factor, but time as well.

My question: Does cosmic expansion overcome the ability for us to ever measure the proper motion of a distant galaxy? Even if we humans lasted another several million years, and we could catalog the received light from a distant galaxy over the course of several million years, would we ever be able to determine its actual proper motion or does the expansion of space make such observations impossible?

Just something I was pondering :D


Our technology is outpacing the expansion of Universe in this regard. :)
Proper motions of galaxies within the local group have already been measured with one galaxy M106 beyond. Most are dwarf galaxies are dwarf galaxies (Large and Small Magellanic Clouds, several dwarf spheroid galaxies) but also the large spiral M33 (Triangulum). Only upper limits have been determined for the Andromeda galaxy (it's coming directly toward us !!)

The observations use natural masers; very compact, single wavelength, intense radio emitters found in star forming regions.
(natural microwave version of lasers).
The references seem to fade out in 2006, so maybe the groups doing this are waiting ...
Not open for further replies.

Latest posts