Re: The Universe In Action

William Rust

The stars in the Milky Way move a lot when seen from the earth.  This is call "proper motion".  That is why the Naval Observatory updates the bright star catalogue every year.  This is not surprising since the earth rotates around the center of gravity of the M.W. and experiences nutation and precession thanks to the moon, tides and other planets pulling us.


From: <> on behalf of Roy Diffrient <mail@...>
Sent: Tuesday, June 29, 2021 10:36 PM
To: BBAA Groups Io <>
Subject: [BackBayAstro] The Universe In Action
Think the universe is moving so slow and distances so vast that no change is visible?  A look at the time lapse images here could change your mind.  Surprising motion of stars and DSO’s shown by Tom Polakis.  This from the Amastro list.

One of my fav’s is the difficult reflection nebula Gyulbudaghian’s Nebula – This image series really explains a lot about the visibility of this object over the last 25 years or so.  



“Something I've spent too much time doing is creating time-lapse sequences using images taken many decades apart.  In this case, here's the motion of HD 134439 and HD 134440 over the course of 34 years.  The 1954 image is from the first Palomar Sky Survey, while the image from 1987 is a UK Schmidt image. The pair of stars moved by more than 2 arcminutes between the two frames.

In case there's interest, here's my gallery of deep-sky object animations.


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